webauthn_rp

WebAuthn Level 3 RP library.
git clone https://git.philomathiclife.com/repos/webauthn_rp
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response.rs (105347B)

      1 extern crate alloc;
      2 use crate::{
      3     request::{register::{PublicKeyCredentialUserEntity, UserHandle}, Challenge, RpId, Url},
      4     response::{
      5         auth::error::{
      6             AuthCeremonyErr, AuthenticatorDataErr as AuthAuthDataErr,
      7             AuthenticatorExtensionOutputErr as AuthAuthExtErr,
      8         },
      9         error::{CollectedClientDataErr, CredentialIdErr},
     10         register::error::{AttestationObjectErr, AttestedCredentialDataErr, AuthenticatorDataErr as RegAuthDataErr, AuthenticatorExtensionOutputErr as RegAuthExtErr, PubKeyErr, RegCeremonyErr},
     11     },
     12 };
     13 use alloc::borrow::Cow;
     14 use core::{
     15     borrow::Borrow,
     16     cmp::Ordering,
     17     convert::Infallible,
     18     fmt::{self, Display, Formatter},
     19     hash::{Hash, Hasher},
     20     str,
     21 };
     22 use rsa::sha2::{digest::OutputSizeUser as _, Sha256};
     23 #[cfg(feature = "serde_relaxed")]
     24 use ser_relaxed::SerdeJsonErr;
     25 /// Contains functionality for completing the
     26 /// [authentication ceremony](https://www.w3.org/TR/webauthn-3/#authentication-ceremony).
     27 ///
     28 /// # Examples
     29 ///
     30 /// ```no_run
     31 /// # use core::convert;
     32 /// # use webauthn_rp::{
     33 /// #     hash::hash_set::MaxLenHashSet,
     34 /// #     request::{auth::{error::InvalidTimeout, DiscoverableAuthenticationClientState, DiscoverableCredentialRequestOptions, AuthenticationVerificationOptions}, register::{UserHandle, USER_HANDLE_MAX_LEN, UserHandle64}, BackupReq, RpId},
     35 /// #     response::{auth::{error::AuthCeremonyErr, DiscoverableAuthentication64}, error::CollectedClientDataErr, register::{AuthenticatorExtensionOutputStaticState, ClientExtensionsOutputsStaticState, CredentialProtectionPolicy, DynamicState, Ed25519PubKey, CompressedPubKeyOwned, StaticState}, AuthenticatorAttachment, Backup, CollectedClientData, CredentialId},
     36 /// #     AuthenticatedCredential, CredentialErr
     37 /// # };
     38 /// # #[derive(Debug)]
     39 /// # enum E {
     40 /// #     CollectedClientData(CollectedClientDataErr),
     41 /// #     InvalidTimeout(InvalidTimeout),
     42 /// #     SerdeJson(serde_json::Error),
     43 /// #     MissingUserHandle,
     44 /// #     MissingCeremony,
     45 /// #     UnknownCredential,
     46 /// #     Credential(CredentialErr),
     47 /// #     AuthCeremony(AuthCeremonyErr),
     48 /// # }
     49 /// # impl From<CollectedClientDataErr> for E {
     50 /// #     fn from(value: CollectedClientDataErr) -> Self {
     51 /// #         Self::CollectedClientData(value)
     52 /// #     }
     53 /// # }
     54 /// # impl From<InvalidTimeout> for E {
     55 /// #     fn from(value: InvalidTimeout) -> Self {
     56 /// #         Self::InvalidTimeout(value)
     57 /// #     }
     58 /// # }
     59 /// # impl From<serde_json::Error> for E {
     60 /// #     fn from(value: serde_json::Error) -> Self {
     61 /// #         Self::SerdeJson(value)
     62 /// #     }
     63 /// # }
     64 /// # impl From<CredentialErr> for E {
     65 /// #     fn from(value: CredentialErr) -> Self {
     66 /// #         Self::Credential(value)
     67 /// #     }
     68 /// # }
     69 /// # impl From<AuthCeremonyErr> for E {
     70 /// #     fn from(value: AuthCeremonyErr) -> Self {
     71 /// #         Self::AuthCeremony(value)
     72 /// #     }
     73 /// # }
     74 /// const RP_ID: &RpId = &RpId::from_static_domain("example.com").unwrap();
     75 /// let mut ceremonies = MaxLenHashSet::new(128);
     76 /// let (server, client) = DiscoverableCredentialRequestOptions::passkey(RP_ID).start_ceremony()?;
     77 /// assert!(
     78 ///     ceremonies.insert_remove_all_expired(server).map_or(false, convert::identity)
     79 /// );
     80 /// # #[cfg(feature = "serde")]
     81 /// let authentication = serde_json::from_str::<DiscoverableAuthentication64>(get_authentication_json(client).as_str())?;
     82 /// # #[cfg(feature = "serde")]
     83 /// let user_handle = authentication.response().user_handle();
     84 /// # #[cfg(feature = "serde")]
     85 /// let (static_state, dynamic_state) = get_credential(authentication.raw_id(), &user_handle).ok_or(E::UnknownCredential)?;
     86 /// # #[cfg(all(feature = "custom", feature = "serde"))]
     87 /// let mut cred = AuthenticatedCredential::new(authentication.raw_id(), &user_handle, static_state, dynamic_state)?;
     88 /// # #[cfg(all(feature = "custom", feature = "serde"))]
     89 /// if ceremonies.take(&authentication.challenge()?).ok_or(E::MissingCeremony)?.verify(RP_ID, &authentication, &mut cred, &AuthenticationVerificationOptions::<&str, &str>::default())? {
     90 ///     update_cred(authentication.raw_id(), cred.dynamic_state());
     91 /// }
     92 /// /// Send `DiscoverableAuthenticationClientState` and receive `DiscoverableAuthentication64` JSON from client.
     93 /// # #[cfg(feature = "serde")]
     94 /// fn get_authentication_json(client: DiscoverableAuthenticationClientState<'_, '_, '_>) -> String {
     95 ///     // ⋮
     96 /// #     let client_data_json = base64url_nopad::encode(serde_json::json!({
     97 /// #         "type": "webauthn.get",
     98 /// #         "challenge": client.options().public_key.challenge,
     99 /// #         "origin": format!("https://{}", client.options().public_key.rp_id.as_ref()),
    100 /// #         "crossOrigin": false
    101 /// #     }).to_string().as_bytes());
    102 /// #     serde_json::json!({
    103 /// #         "id": "AAAAAAAAAAAAAAAAAAAAAA",
    104 /// #         "rawId": "AAAAAAAAAAAAAAAAAAAAAA",
    105 /// #         "response": {
    106 /// #             "clientDataJSON": client_data_json,
    107 /// #             "authenticatorData": "",
    108 /// #             "signature": "",
    109 /// #             "userHandle": "AA"
    110 /// #         },
    111 /// #         "clientExtensionResults": {},
    112 /// #         "type": "public-key"
    113 /// #     }).to_string()
    114 /// }
    115 /// /// Gets the `AuthenticatedCredential` parts associated with `id` and `user_handle` from the database.
    116 /// fn get_credential(id: CredentialId<&[u8]>, user_handle: &UserHandle64) -> Option<(StaticState<CompressedPubKeyOwned>, DynamicState)> {
    117 ///     // ⋮
    118 /// #     Some((StaticState { credential_public_key: CompressedPubKeyOwned::Ed25519(Ed25519PubKey::from([0; 32])), extensions: AuthenticatorExtensionOutputStaticState { cred_protect: CredentialProtectionPolicy::UserVerificationRequired, hmac_secret: None, }, client_extension_results: ClientExtensionsOutputsStaticState { prf: None, }, }, DynamicState { user_verified: true, backup: Backup::NotEligible, sign_count: 1, authenticator_attachment: AuthenticatorAttachment::None }))
    119 /// }
    120 /// /// Updates the current `DynamicState` associated with `id` in the database to
    121 /// /// `dyn_state`.
    122 /// fn update_cred(id: CredentialId<&[u8]>, dyn_state: DynamicState) {
    123 ///     // ⋮
    124 /// }
    125 /// # Ok::<_, E>(())
    126 /// ```
    127 pub mod auth;
    128 /// Contains functionality to (de)serialize data to a data store.
    129 #[cfg(feature = "bin")]
    130 pub mod bin;
    131 /// Contains constants useful for
    132 /// [CTAP2 canonical CBOR encoding form](https://fidoalliance.org/specs/fido-v2.2-rd-20230321/fido-client-to-authenticator-protocol-v2.2-rd-20230321.html#ctap2-canonical-cbor-encoding-form).
    133 mod cbor;
    134 /// Contains functionality that needs to be accessible when `bin` or `serde` are not enabled.
    135 #[cfg(feature = "custom")]
    136 pub mod custom;
    137 /// Contains error types.
    138 pub mod error;
    139 /// Contains functionality for completing the
    140 /// [registration ceremony](https://www.w3.org/TR/webauthn-3/#registration-ceremony).
    141 ///
    142 /// # Examples
    143 ///
    144 /// ```no_run
    145 /// # use core::convert;
    146 /// # use webauthn_rp::{
    147 /// #     hash::hash_set::MaxLenHashSet,
    148 /// #     request::{register::{error::CreationOptionsErr, CredentialCreationOptions, DisplayName, PublicKeyCredentialUserEntity, RegistrationClientState, UserHandle, UserHandle64, USER_HANDLE_MAX_LEN, RegistrationVerificationOptions}, PublicKeyCredentialDescriptor, RpId},
    149 /// #     response::{register::{error::RegCeremonyErr, Registration}, error::CollectedClientDataErr, CollectedClientData},
    150 /// #     RegisteredCredential
    151 /// # };
    152 /// # #[derive(Debug)]
    153 /// # enum E {
    154 /// #     CollectedClientData(CollectedClientDataErr),
    155 /// #     CreationOptions(CreationOptionsErr),
    156 /// #     SerdeJson(serde_json::Error),
    157 /// #     MissingCeremony,
    158 /// #     RegCeremony(RegCeremonyErr),
    159 /// # }
    160 /// # impl From<CollectedClientDataErr> for E {
    161 /// #     fn from(value: CollectedClientDataErr) -> Self {
    162 /// #         Self::CollectedClientData(value)
    163 /// #     }
    164 /// # }
    165 /// # impl From<CreationOptionsErr> for E {
    166 /// #     fn from(value: CreationOptionsErr) -> Self {
    167 /// #         Self::CreationOptions(value)
    168 /// #     }
    169 /// # }
    170 /// # impl From<serde_json::Error> for E {
    171 /// #     fn from(value: serde_json::Error) -> Self {
    172 /// #         Self::SerdeJson(value)
    173 /// #     }
    174 /// # }
    175 /// # impl From<RegCeremonyErr> for E {
    176 /// #     fn from(value: RegCeremonyErr) -> Self {
    177 /// #         Self::RegCeremony(value)
    178 /// #     }
    179 /// # }
    180 /// const RP_ID: &RpId = &RpId::from_static_domain("example.com").unwrap();
    181 /// # #[cfg(feature = "custom")]
    182 /// let mut ceremonies = MaxLenHashSet::new(128);
    183 /// # #[cfg(feature = "custom")]
    184 /// let user_handle = get_user_handle();
    185 /// # #[cfg(feature = "custom")]
    186 /// let user = get_user_entity(&user_handle);
    187 /// # #[cfg(feature = "custom")]
    188 /// let creds = get_registered_credentials(user_handle);
    189 /// # #[cfg(feature = "custom")]
    190 /// let (server, client) = CredentialCreationOptions::passkey(RP_ID, user, creds).start_ceremony()?;
    191 /// # #[cfg(feature = "custom")]
    192 /// assert!(
    193 ///     ceremonies.insert_remove_all_expired(server).map_or(false, convert::identity)
    194 /// );
    195 /// # #[cfg(all(feature = "serde_relaxed", feature = "custom"))]
    196 /// let registration = serde_json::from_str::<Registration>(get_registration_json(client).as_str())?;
    197 /// let ver_opts = RegistrationVerificationOptions::<&str, &str>::default();
    198 /// # #[cfg(all(feature = "custom", feature = "serde_relaxed"))]
    199 /// insert_cred(ceremonies.take(&registration.challenge()?).ok_or(E::MissingCeremony)?.verify(RP_ID, &registration, &ver_opts)?);
    200 /// /// Extract `UserHandle` from session cookie if this is not the first credential registered.
    201 /// # #[cfg(feature = "custom")]
    202 /// fn get_user_handle() -> UserHandle64 {
    203 ///     // ⋮
    204 /// #     [0; USER_HANDLE_MAX_LEN].into()
    205 /// }
    206 /// /// Fetch `PublicKeyCredentialUserEntity` info associated with `user`.
    207 /// ///
    208 /// /// If this is the first time a credential is being registered, then `PublicKeyCredentialUserEntity`
    209 /// /// will need to be constructed with `name` and `display_name` passed from the client and `UserHandle::new`
    210 /// /// used for `id`. Once created, this info can be stored such that the entity information
    211 /// /// does not need to be requested for subsequent registrations.
    212 /// # #[cfg(feature = "custom")]
    213 /// fn get_user_entity(user: &UserHandle<USER_HANDLE_MAX_LEN>) -> PublicKeyCredentialUserEntity<'_, '_, '_, USER_HANDLE_MAX_LEN> {
    214 ///     // ⋮
    215 /// #     PublicKeyCredentialUserEntity {
    216 /// #         name: "foo".try_into().unwrap(),
    217 /// #         id: user,
    218 /// #         display_name: DisplayName::Blank,
    219 /// #     }
    220 /// }
    221 /// /// Send `RegistrationClientState` and receive `Registration` JSON from client.
    222 /// # #[cfg(feature = "serde")]
    223 /// fn get_registration_json(client: RegistrationClientState<'_, '_, '_, '_, '_, '_, USER_HANDLE_MAX_LEN>) -> String {
    224 ///     // ⋮
    225 /// #     let client_data_json = base64url_nopad::encode(serde_json::json!({
    226 /// #         "type": "webauthn.create",
    227 /// #         "challenge": client.options().public_key.challenge,
    228 /// #         "origin": format!("https://{}", client.options().public_key.rp_id.as_ref()),
    229 /// #         "crossOrigin": false
    230 /// #     }).to_string().as_bytes());
    231 /// #     serde_json::json!({
    232 /// #         "response": {
    233 /// #             "clientDataJSON": client_data_json,
    234 /// #             "attestationObject": ""
    235 /// #         }
    236 /// #     }).to_string()
    237 /// }
    238 /// /// Fetch the `PublicKeyCredentialDescriptor`s associated with `user`.
    239 /// ///
    240 /// /// This doesn't need to be called when this is the first credential registered for `user`; instead
    241 /// /// an empty `Vec` should be passed.
    242 /// fn get_registered_credentials(
    243 ///     user: UserHandle<USER_HANDLE_MAX_LEN>,
    244 /// ) -> Vec<PublicKeyCredentialDescriptor<Vec<u8>>> {
    245 ///     // ⋮
    246 /// #     Vec::new()
    247 /// }
    248 /// /// Inserts `RegisteredCredential::into_parts` into the database.
    249 /// fn insert_cred(cred: RegisteredCredential<'_, USER_HANDLE_MAX_LEN>) {
    250 ///     // ⋮
    251 /// }
    252 /// # Ok::<_, E>(())
    253 /// ```
    254 pub mod register;
    255 /// Contains functionality to (de)serialize data to/from a client.
    256 #[cfg(feature = "serde")]
    257 pub(crate) mod ser;
    258 /// Contains functionality to deserialize data from a client in a "relaxed" way.
    259 #[cfg(feature = "serde_relaxed")]
    260 pub mod ser_relaxed;
    261 /// [Backup eligibility](https://www.w3.org/TR/webauthn-3/#backup-eligibility) and
    262 /// [backup state](https://www.w3.org/TR/webauthn-3/#backup-state).
    263 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    264 pub enum Backup {
    265     /// [BE and BS](https://www.w3.org/TR/webauthn-3/#authdata-flags) flags are `0`.
    266     NotEligible,
    267     /// [BE and BS](https://www.w3.org/TR/webauthn-3/#authdata-flags) flags are `1` and `0` respectively.
    268     Eligible,
    269     /// [BE and BS](https://www.w3.org/TR/webauthn-3/#authdata-flags) flags are `1`.
    270     Exists,
    271 }
    272 impl PartialEq<&Self> for Backup {
    273     #[inline]
    274     fn eq(&self, other: &&Self) -> bool {
    275         *self == **other
    276     }
    277 }
    278 impl PartialEq<Backup> for &Backup {
    279     #[inline]
    280     fn eq(&self, other: &Backup) -> bool {
    281         **self == *other
    282     }
    283 }
    284 /// [`AuthenticatorTransport`](https://www.w3.org/TR/webauthn-3/#enumdef-authenticatortransport).
    285 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    286 pub enum AuthenticatorTransport {
    287     /// [`ble`](https://www.w3.org/TR/webauthn-3/#dom-authenticatortransport-ble).
    288     Ble,
    289     /// [`hybrid`](https://www.w3.org/TR/webauthn-3/#dom-authenticatortransport-hybrid).
    290     Hybrid,
    291     /// [`internal`](https://www.w3.org/TR/webauthn-3/#dom-authenticatortransport-internal).
    292     Internal,
    293     /// [`nfc`](https://www.w3.org/TR/webauthn-3/#dom-authenticatortransport-nfc).
    294     Nfc,
    295     /// [`smart-card`](https://www.w3.org/TR/webauthn-3/#dom-authenticatortransport-smart-card).
    296     SmartCard,
    297     /// [`usb`](https://www.w3.org/TR/webauthn-3/#dom-authenticatortransport-usb).
    298     Usb,
    299 }
    300 impl AuthenticatorTransport {
    301     /// Returns the encoded [`u8`] that `self` represents.
    302     const fn to_u8(self) -> u8 {
    303         match self {
    304             Self::Ble => 0x1,
    305             Self::Hybrid => 0x2,
    306             Self::Internal => 0x4,
    307             Self::Nfc => 0x8,
    308             Self::SmartCard => 0x10,
    309             Self::Usb => 0x20,
    310         }
    311     }
    312 }
    313 /// Set of [`AuthenticatorTransport`]s.
    314 #[derive(Clone, Copy, Debug)]
    315 pub struct AuthTransports(u8);
    316 impl AuthTransports {
    317     /// An empty `AuthTransports`.
    318     #[cfg(feature = "custom")]
    319     pub const NONE: Self = Self::new();
    320     /// An `AuthTransports` containing all possible [`AuthenticatorTransport`]s.
    321     #[cfg(feature = "custom")]
    322     pub const ALL: Self = Self::all();
    323     /// Construct an empty `AuthTransports`.
    324     #[cfg(any(feature = "bin", feature = "custom", feature = "serde"))]
    325     pub(super) const fn new() -> Self {
    326         Self(0)
    327     }
    328     #[cfg(any(feature = "bin", feature = "custom"))]
    329     /// Construct an `AuthTransports` containing all `AuthenticatorTransport`s.
    330     const fn all() -> Self {
    331         Self::new()
    332             .add_transport(AuthenticatorTransport::Ble)
    333             .add_transport(AuthenticatorTransport::Hybrid)
    334             .add_transport(AuthenticatorTransport::Internal)
    335             .add_transport(AuthenticatorTransport::Nfc)
    336             .add_transport(AuthenticatorTransport::SmartCard)
    337             .add_transport(AuthenticatorTransport::Usb)
    338     }
    339     /// Returns the number of [`AuthenticatorTransport`]s in `self`.
    340     ///
    341     /// # Examples
    342     ///
    343     /// ```
    344     /// # use webauthn_rp::response::AuthTransports;
    345     /// # #[cfg(feature = "custom")]
    346     /// assert_eq!(AuthTransports::ALL.count(), 6);
    347     /// ```
    348     #[inline]
    349     #[must_use]
    350     pub const fn count(self) -> u32 {
    351         self.0.count_ones()
    352     }
    353     /// Returns `true` iff there are no [`AuthenticatorTransport`]s in `self`.
    354     ///
    355     /// # Examples
    356     ///
    357     /// ```
    358     /// # use webauthn_rp::response::AuthTransports;
    359     /// # #[cfg(feature = "custom")]
    360     /// assert!(AuthTransports::NONE.is_empty());
    361     /// ```
    362     #[inline]
    363     #[must_use]
    364     pub const fn is_empty(self) -> bool {
    365         self.0 == 0
    366     }
    367     /// Returns `true` iff `self` contains `transport`.
    368     ///
    369     /// # Examples
    370     ///
    371     /// ```
    372     /// # use webauthn_rp::response::{AuthTransports, AuthenticatorTransport};
    373     /// # #[cfg(feature = "custom")]
    374     /// assert!(AuthTransports::ALL.contains(AuthenticatorTransport::Ble));
    375     /// ```
    376     #[inline]
    377     #[must_use]
    378     pub const fn contains(self, transport: AuthenticatorTransport) -> bool {
    379         let val = transport.to_u8();
    380         self.0 & val == val
    381     }
    382     /// Returns a copy of `self` with `transport` added.
    383     ///
    384     /// `self` is returned iff `transport` already exists.
    385     #[cfg(any(feature = "bin", feature = "custom", feature = "serde"))]
    386     const fn add_transport(self, transport: AuthenticatorTransport) -> Self {
    387         Self(self.0 | transport.to_u8())
    388     }
    389     /// Returns a copy of `self` with `transport` added.
    390     ///
    391     /// `self` is returned iff `transport` already exists.
    392     ///
    393     /// # Examples
    394     ///
    395     /// ```
    396     /// # use webauthn_rp::response::{AuthTransports, AuthenticatorTransport};
    397     /// assert_eq!(
    398     ///     AuthTransports::NONE
    399     ///         .add(AuthenticatorTransport::Usb)
    400     ///         .count(),
    401     ///     1
    402     /// );
    403     /// assert_eq!(
    404     ///     AuthTransports::ALL.add(AuthenticatorTransport::Usb).count(),
    405     ///     6
    406     /// );
    407     /// ```
    408     #[cfg(feature = "custom")]
    409     #[inline]
    410     #[must_use]
    411     pub const fn add(self, transport: AuthenticatorTransport) -> Self {
    412         self.add_transport(transport)
    413     }
    414     /// Returns a copy of `self` with `transport` removed.
    415     ///
    416     /// `self` is returned iff `transport` did not exist.
    417     ///
    418     /// # Examples
    419     ///
    420     /// ```
    421     /// # use webauthn_rp::response::{AuthTransports, AuthenticatorTransport};
    422     /// assert_eq!(
    423     ///     AuthTransports::ALL
    424     ///         .remove(AuthenticatorTransport::Internal)
    425     ///         .count(),
    426     ///     5
    427     /// );
    428     /// assert_eq!(
    429     ///     AuthTransports::NONE.remove(AuthenticatorTransport::Usb).count(),
    430     ///     0
    431     /// );
    432     /// ```
    433     #[cfg(feature = "custom")]
    434     #[inline]
    435     #[must_use]
    436     pub const fn remove(self, transport: AuthenticatorTransport) -> Self {
    437         Self(self.0 & !transport.to_u8())
    438     }
    439 }
    440 /// [`AuthenticatorAttachment`](https://www.w3.org/TR/webauthn-3/#enumdef-authenticatorattachment).
    441 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    442 pub enum AuthenticatorAttachment {
    443     /// No attachment information.
    444     None,
    445     /// [`platform`](https://www.w3.org/TR/webauthn-3/#dom-authenticatorattachment-platform).
    446     Platform,
    447     /// [`cross-platform`](https://www.w3.org/TR/webauthn-3/#dom-authenticatorattachment-cross-platform).
    448     CrossPlatform,
    449 }
    450 impl PartialEq<&Self> for AuthenticatorAttachment {
    451     #[inline]
    452     fn eq(&self, other: &&Self) -> bool {
    453         *self == **other
    454     }
    455 }
    456 impl PartialEq<AuthenticatorAttachment> for &AuthenticatorAttachment {
    457     #[inline]
    458     fn eq(&self, other: &AuthenticatorAttachment) -> bool {
    459         **self == *other
    460     }
    461 }
    462 /// The maximum number of bytes that can make up a Credential ID
    463 /// [per WebAuthn](https://www.w3.org/TR/webauthn-3/#credential-id).
    464 pub const CRED_ID_MAX_LEN: usize = 1023;
    465 /// The minimum number of bytes that can make up a Credential ID
    466 /// [per WebAuthn](https://www.w3.org/TR/webauthn-3/#credential-id).
    467 ///
    468 /// The spec does not call out this value directly instead it states the following:
    469 ///
    470 /// > Credential IDs are generated by authenticators in two forms:
    471 /// >
    472 /// > * At least 16 bytes that include at least 100 bits of entropy, or
    473 /// > * The [public key credential source](https://www.w3.org/TR/webauthn-3/#public-key-credential-source),
    474 /// >   without its Credential ID or mutable items, encrypted so only its managing
    475 /// >   authenticator can decrypt it. This form allows the authenticator to be nearly
    476 /// >   stateless, by having the Relying Party store any necessary state.
    477 ///
    478 /// One of the immutable items of the public key credential source is the private key
    479 /// which for any real-world signature algorithm will always be at least 16 bytes.
    480 pub const CRED_ID_MIN_LEN: usize = 16;
    481 /// A [Credential ID](https://www.w3.org/TR/webauthn-3/#credential-id) that is made up of
    482 /// [`CRED_ID_MIN_LEN`]–[`CRED_ID_MAX_LEN`] bytes.
    483 #[derive(Clone, Copy, Debug)]
    484 pub struct CredentialId<T>(T);
    485 impl<T> CredentialId<T> {
    486     /// Returns the contained data consuming `self`.
    487     #[inline]
    488     pub fn into_inner(self) -> T {
    489         self.0
    490     }
    491     /// Returns the contained data.
    492     #[inline]
    493     pub const fn inner(&self) -> &T {
    494         &self.0
    495     }
    496 }
    497 impl<'a> CredentialId<&'a [u8]> {
    498     /// Creates a `CredentialId` from a `slice`.
    499     #[expect(single_use_lifetimes, reason = "false positive")]
    500     fn from_slice<'b: 'a>(value: &'b [u8]) -> Result<Self, CredentialIdErr> {
    501         if (CRED_ID_MIN_LEN..=CRED_ID_MAX_LEN).contains(&value.len()) {
    502             Ok(Self(value))
    503         } else {
    504             Err(CredentialIdErr)
    505         }
    506     }
    507 }
    508 impl<T: AsRef<[u8]>> AsRef<[u8]> for CredentialId<T> {
    509     #[inline]
    510     fn as_ref(&self) -> &[u8] {
    511         self.0.as_ref()
    512     }
    513 }
    514 impl<T: Borrow<[u8]>> Borrow<[u8]> for CredentialId<T> {
    515     #[inline]
    516     fn borrow(&self) -> &[u8] {
    517         self.0.borrow()
    518     }
    519 }
    520 impl<'a: 'b, 'b> From<&'a CredentialId<Vec<u8>>> for CredentialId<&'b Vec<u8>> {
    521     #[inline]
    522     fn from(value: &'a CredentialId<Vec<u8>>) -> Self {
    523         Self(&value.0)
    524     }
    525 }
    526 impl<'a: 'b, 'b> From<CredentialId<&'a Vec<u8>>> for CredentialId<&'b [u8]> {
    527     #[inline]
    528     fn from(value: CredentialId<&'a Vec<u8>>) -> Self {
    529         Self(value.0.as_slice())
    530     }
    531 }
    532 impl<'a: 'b, 'b> From<&'a CredentialId<Vec<u8>>> for CredentialId<&'b [u8]> {
    533     #[inline]
    534     fn from(value: &'a CredentialId<Vec<u8>>) -> Self {
    535         Self(value.0.as_slice())
    536     }
    537 }
    538 impl From<CredentialId<&[u8]>> for CredentialId<Vec<u8>> {
    539     #[inline]
    540     fn from(value: CredentialId<&[u8]>) -> Self {
    541         Self(value.0.to_owned())
    542     }
    543 }
    544 impl<T: PartialEq<T2>, T2: PartialEq<T>> PartialEq<CredentialId<T>> for CredentialId<T2> {
    545     #[inline]
    546     fn eq(&self, other: &CredentialId<T>) -> bool {
    547         self.0 == other.0
    548     }
    549 }
    550 impl<T: PartialEq<T2>, T2: PartialEq<T>> PartialEq<CredentialId<T>> for &CredentialId<T2> {
    551     #[inline]
    552     fn eq(&self, other: &CredentialId<T>) -> bool {
    553         **self == *other
    554     }
    555 }
    556 impl<T: PartialEq<T2>, T2: PartialEq<T>> PartialEq<&CredentialId<T>> for CredentialId<T2> {
    557     #[inline]
    558     fn eq(&self, other: &&CredentialId<T>) -> bool {
    559         *self == **other
    560     }
    561 }
    562 impl<T: Eq> Eq for CredentialId<T> {}
    563 impl<T: Hash> Hash for CredentialId<T> {
    564     #[inline]
    565     fn hash<H: Hasher>(&self, state: &mut H) {
    566         self.0.hash(state);
    567     }
    568 }
    569 impl<T: PartialOrd<T2>, T2: PartialOrd<T>> PartialOrd<CredentialId<T>> for CredentialId<T2> {
    570     #[inline]
    571     fn partial_cmp(&self, other: &CredentialId<T>) -> Option<Ordering> {
    572         self.0.partial_cmp(&other.0)
    573     }
    574 }
    575 impl<T: Ord> Ord for CredentialId<T> {
    576     #[inline]
    577     fn cmp(&self, other: &Self) -> Ordering {
    578         self.0.cmp(&other.0)
    579     }
    580 }
    581 // We define a separate type to ensure challenges sent to the client are always randomly generated;
    582 // otherwise one could deserialize arbitrary data into a `Challenge`.
    583 /// Copy of [`Challenge`] sent back from the client.
    584 #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    585 pub struct SentChallenge(pub u128);
    586 impl SentChallenge {
    587     /// Transforms `value` into a `SentChallenge` by interpreting `value` as a
    588     /// little-endian `u128`.
    589     #[expect(clippy::little_endian_bytes, reason = "Challenge and SentChallenge need to be compatible, and we need to ensure the data is sent and received in the same order")]
    590     #[inline]
    591     #[must_use]
    592     pub const fn from_array(value: [u8; 16]) -> Self {
    593         Self(u128::from_le_bytes(value))
    594     }
    595     /// Transforms `value` into a `SentChallenge`.
    596     #[inline]
    597     #[must_use]
    598     pub const fn from_challenge(value: Challenge) -> Self {
    599         Self(value.into_data())
    600     }
    601 }
    602 impl From<Challenge> for SentChallenge {
    603     #[inline]
    604     fn from(value: Challenge) -> Self {
    605         Self::from_challenge(value)
    606     }
    607 }
    608 impl From<[u8; 16]> for SentChallenge {
    609     #[inline]
    610     fn from(value: [u8; 16]) -> Self {
    611         Self::from_array(value)
    612     }
    613 }
    614 impl PartialEq<&Self> for SentChallenge {
    615     #[inline]
    616     fn eq(&self, other: &&Self) -> bool {
    617         *self == **other
    618     }
    619 }
    620 impl PartialEq<SentChallenge> for &SentChallenge {
    621     #[inline]
    622     fn eq(&self, other: &SentChallenge) -> bool {
    623         **self == *other
    624     }
    625 }
    626 impl PartialOrd for SentChallenge {
    627     #[inline]
    628     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
    629         Some(self.cmp(other))
    630     }
    631 }
    632 impl Ord for SentChallenge {
    633     #[inline]
    634     fn cmp(&self, other: &Self) -> Ordering {
    635         self.0.cmp(&other.0)
    636     }
    637 }
    638 impl Hash for SentChallenge {
    639     #[inline]
    640     fn hash<H: Hasher>(&self, state: &mut H) {
    641         state.write_u128(self.0);
    642     }
    643 }
    644 /// An [`origin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-origin) or
    645 /// [`topOrigin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-toporigin).
    646 #[derive(Debug, Eq)]
    647 pub struct Origin<'a>(pub Cow<'a, str>);
    648 impl PartialEq<Origin<'_>> for Origin<'_> {
    649     #[inline]
    650     fn eq(&self, other: &Origin<'_>) -> bool {
    651         self.0 == other.0
    652     }
    653 }
    654 impl PartialEq<&Origin<'_>> for Origin<'_> {
    655     #[inline]
    656     fn eq(&self, other: &&Origin<'_>) -> bool {
    657         *self == **other
    658     }
    659 }
    660 impl PartialEq<Origin<'_>> for &Origin<'_> {
    661     #[inline]
    662     fn eq(&self, other: &Origin<'_>) -> bool {
    663         **self == *other
    664     }
    665 }
    666 impl PartialEq<str> for Origin<'_> {
    667     #[inline]
    668     fn eq(&self, other: &str) -> bool {
    669         self.0.as_ref() == other
    670     }
    671 }
    672 impl PartialEq<Origin<'_>> for str {
    673     #[inline]
    674     fn eq(&self, other: &Origin<'_>) -> bool {
    675         *other == *self
    676     }
    677 }
    678 impl PartialEq<&str> for Origin<'_> {
    679     #[inline]
    680     fn eq(&self, other: &&str) -> bool {
    681         *self == **other
    682     }
    683 }
    684 impl PartialEq<Origin<'_>> for &str {
    685     #[inline]
    686     fn eq(&self, other: &Origin<'_>) -> bool {
    687         **self == *other
    688     }
    689 }
    690 impl PartialEq<String> for Origin<'_> {
    691     #[inline]
    692     fn eq(&self, other: &String) -> bool {
    693         self.0 == *other
    694     }
    695 }
    696 impl PartialEq<Origin<'_>> for String {
    697     #[inline]
    698     fn eq(&self, other: &Origin<'_>) -> bool {
    699         *other == *self
    700     }
    701 }
    702 impl PartialEq<Url> for Origin<'_> {
    703     #[inline]
    704     fn eq(&self, other: &Url) -> bool {
    705         self.0.as_ref() == other.as_ref()
    706     }
    707 }
    708 impl PartialEq<Origin<'_>> for Url {
    709     #[inline]
    710     fn eq(&self, other: &Origin<'_>) -> bool {
    711         *other == *self
    712     }
    713 }
    714 impl PartialEq<&Url> for Origin<'_> {
    715     #[inline]
    716     fn eq(&self, other: &&Url) -> bool {
    717         *self == **other
    718     }
    719 }
    720 impl PartialEq<Origin<'_>> for &Url {
    721     #[inline]
    722     fn eq(&self, other: &Origin<'_>) -> bool {
    723         **self == *other
    724     }
    725 }
    726 /// [Authenticator data flags](https://www.w3.org/TR/webauthn-3/#authdata-flags).
    727 #[derive(Clone, Copy, Debug)]
    728 pub struct Flag {
    729     /// [`UP` flag](https://www.w3.org/TR/webauthn-3/#authdata-flags-up).
    730     ///
    731     /// Note this is always `true` when part of [`auth::AuthenticatorData::flags`].
    732     pub user_present: bool,
    733     /// [`UV` flag](https://www.w3.org/TR/webauthn-3/#concept-user-verified).
    734     pub user_verified: bool,
    735     /// [`BE`](https://www.w3.org/TR/webauthn-3/#backup-eligibility) and
    736     /// [`BS`](https://www.w3.org/TR/webauthn-3/#backup-state) flags.
    737     pub backup: Backup,
    738 }
    739 /// [Authenticator data](https://www.w3.org/TR/webauthn-3/#authenticator-data).
    740 pub(super) trait AuthData<'a>: Sized {
    741     /// Error returned by [`Self::user_is_not_present`].
    742     ///
    743     /// This should be [`Infallible`] in the event user must not always be present.
    744     type UpBitErr;
    745     /// [`attestedCredentialData`](https://www.w3.org/TR/webauthn-3/#authdata-attestedcredentialdata).
    746     type CredData;
    747     /// [`extensions`](https://www.w3.org/TR/webauthn-3/#authdata-extensions).
    748     type Ext: AuthExtOutput + Copy;
    749     /// Errors iff the user must always be present.
    750     fn user_is_not_present() -> Result<(), Self::UpBitErr>;
    751     /// `true` iff `AT` bit (i.e., bit 6) in [`Self::flag_data`] can and must be set to 1.
    752     fn contains_at_bit() -> bool;
    753     /// Constructor.
    754     fn new(rp_id_hash: &'a [u8], flags: Flag, sign_count: u32, attested_credential_data: Self::CredData, extensions: Self::Ext) -> Self;
    755     /// [`rpIdHash`](https://www.w3.org/TR/webauthn-3/#authdata-rpidhash).
    756     fn rp_hash(&self) -> &'a [u8];
    757     /// [`flags`](https://www.w3.org/TR/webauthn-3/#authdata-flags).
    758     fn flag(&self) -> Flag;
    759 }
    760 /// [`CollectedClientData`](https://www.w3.org/TR/webauthn-3/#dictdef-collectedclientdata).
    761 #[derive(Debug)]
    762 pub struct CollectedClientData<'a> {
    763     /// [`challenge`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-challenge).
    764     pub challenge: SentChallenge,
    765     /// [`origin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-origin).
    766     pub origin: Origin<'a>,
    767     /// [`crossOrigin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-crossorigin).
    768     pub cross_origin: bool,
    769     /// [`topOrigin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-toporigin).
    770     ///
    771     /// When `CollectedClientData` is constructed via [`Self::from_client_data_json`], this can only be
    772     /// `Some` if [`Self::cross_origin`]; and if `Some`, it will be different than [`Self::origin`].
    773     pub top_origin: Option<Origin<'a>>,
    774 }
    775 impl<'a> CollectedClientData<'a> {
    776     /// Parses `json` based on the
    777     /// [limited verification algorithm](https://www.w3.org/TR/webauthn-3/#clientdatajson-verification).
    778     ///
    779     /// Additionally, [`topOrigin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-toporigin) is only
    780     /// allowed to exist if it has a different value than
    781     /// [`origin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-origin) and
    782     /// [`crossOrigin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-crossorigin) is `true`.
    783     ///
    784     /// `REGISTRATION` iff [`type`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-type) must be
    785     /// `"webauthn.create"`; otherwise it must be `"webauthn.get"`.
    786     ///
    787     /// # Errors
    788     ///
    789     /// Errors iff `json` cannot be parsed based on the aforementioned requirements.
    790     ///
    791     /// # Examples
    792     ///
    793     /// ```
    794     /// # use webauthn_rp::response::{error::CollectedClientDataErr, CollectedClientData};
    795     /// assert!(!CollectedClientData::from_client_data_json::<true>(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice())?.cross_origin);
    796     /// assert!(!CollectedClientData::from_client_data_json::<false>(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice())?.cross_origin);
    797     /// # Ok::<_, CollectedClientDataErr>(())
    798     /// ```
    799     #[expect(single_use_lifetimes, reason = "false positive")]
    800     #[inline]
    801     pub fn from_client_data_json<'b: 'a, const REGISTRATION: bool>(json: &'b [u8]) -> Result<Self, CollectedClientDataErr> {
    802         LimitedVerificationParser::<REGISTRATION>::parse(json)
    803     }
    804     /// Parses `json` in a "relaxed" way.
    805     ///
    806     /// Unlike [`Self::from_client_data_json`] which requires `json` to be an output from the
    807     /// [JSON-compatible serialization of client data](https://www.w3.org/TR/webauthn-3/#clientdatajson-serialization),
    808     /// this parses `json` based entirely on the
    809     /// [`CollectedClientData`](https://www.w3.org/TR/webauthn-3/#dictdef-collectedclientdata) Web IDL `dictionary`.
    810     ///
    811     /// L1 clients predate the JSON-compatible serialization of client data; additionally there are L2 and L3
    812     /// clients that don't adhere to the JSON-compatible serialization of client data despite being required to.
    813     /// These clients serialize `CollectedClientData` so that it's valid JSON and conforms to the Web IDL `dictionary`
    814     /// and nothing more. Furthermore, when not relying on the
    815     /// [limited verification algorithm](https://www.w3.org/TR/webauthn-3/#clientdatajson-verification), the spec
    816     /// requires the data to be decoded in a way equivalent to
    817     /// [UTF-8 decode](https://encoding.spec.whatwg.org/#utf-8-decode) which both interprets a leading zero
    818     /// width no-breaking space (i.e., U+FEFF) as a byte-order mark (BOM) as well as replaces any sequences of
    819     /// invalid UTF-8 code units with the replacement character (i.e., U+FFFD). That is precisely what this
    820     /// function does.
    821     ///
    822     /// # Errors
    823     ///
    824     /// Errors iff any of the following is true:
    825     /// * The payload is not valid JSON _after_ ignoring a leading U+FEFF and replacing any sequences of invalid
    826     ///   UTF-8 code units with U+FFFD.
    827     /// * The JSON does not conform to the Web IDL `dictionary`.
    828     /// * [`type`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-type) is not `"webauthn.create"`
    829     ///   or `"webauthn.get"` when `REGISTRATION` and `!REGISTRATION` respectively.
    830     /// * [`challenge`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-challenge) is not a
    831     ///   base64url-encoded [`Challenge`].
    832     /// * Existence of duplicate keys for the keys that are expected.
    833     ///
    834     /// # Examples
    835     ///
    836     /// ```
    837     /// # use webauthn_rp::response::{ser_relaxed::SerdeJsonErr, CollectedClientData};
    838     /// assert!(!CollectedClientData::from_client_data_json_relaxed::<true>(b"\xef\xbb\xbf{
    839     ///   \"type\": \"webauthn.create\",
    840     ///   \"origin\": \"https://example.com\",
    841     ///   \"f\xffo\": 123,
    842     ///   \"topOrigin\": \"https://example.com\",
    843     ///   \"challenge\": \"AAAAAAAAAAAAAAAAAAAAAA\"
    844     /// }")?.cross_origin);
    845     /// # Ok::<_, SerdeJsonErr>(())
    846     /// ```
    847     #[expect(single_use_lifetimes, reason = "false positive")]
    848     #[cfg(feature = "serde_relaxed")]
    849     #[inline]
    850     pub fn from_client_data_json_relaxed<'b: 'a, const REGISTRATION: bool>(json: &'b [u8]) -> Result<Self, SerdeJsonErr> {
    851         ser_relaxed::RelaxedClientDataJsonParser::<REGISTRATION>::parse(json)
    852     }
    853 }
    854 /// Parser of 
    855 /// [`JSON-compatible serialization of client data`](https://www.w3.org/TR/webauthn-3/#collectedclientdata-json-compatible-serialization-of-client-data).
    856 trait ClientDataJsonParser {
    857     /// Error returned by [`Self::parse`].
    858     type Err;
    859     /// Parses `json` into `CollectedClientData` based on the value of
    860     /// [`type`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-type).
    861     ///
    862     /// # Errors
    863     ///
    864     /// Errors iff `json` cannot be parsed into a `CollectedClientData`.
    865     fn parse(json: &[u8]) -> Result<CollectedClientData<'_>, Self::Err>;
    866     /// Extracts [`challenge`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-challenge)
    867     /// from `json`.
    868     ///
    869     /// Note `json` should be minimally parsed such that only `challenge` is extracted; thus
    870     /// `Ok` being returned does _not_ mean `json` is in fact valid.
    871     fn get_sent_challenge(json: &[u8]) -> Result<SentChallenge, Self::Err>;
    872 }
    873 /// [`ClientDataJsonParser`] based on the
    874 /// [limited verification algorithm](https://www.w3.org/TR/webauthn-3/#clientdatajson-verification)
    875 /// with the following additional requirements:
    876 /// * Unknown keys are not allowed.
    877 /// * The entire payload is parsed; thus the payload is guaranteed to be valid UTF-8 and JSON.
    878 /// * [`CollectedClientData::top_origin`] can only be `Some` if
    879 ///   [`crossOrigin`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-crossorigin).
    880 /// * If `CollectedClientData::top_origin` is `Some`, then it does not equal [`CollectedClientData::origin`].
    881 ///
    882 /// `REGISTRATION` iff [`ClientDataJsonParser::parse`] requires
    883 /// [`type`](https://www.w3.org/TR/webauthn-3/#dom-collectedclientdata-type) to be `"webauthn.create"`;
    884 /// otherwise it must be `"webauthn.get"`.
    885 struct LimitedVerificationParser<const REGISTRATION: bool>;
    886 impl<const R: bool> LimitedVerificationParser<R> {
    887     /// Parses `val` as a JSON string with possibly trailing data. `val` MUST NOT begin with an opening quote. Upon
    888     /// encountering the first non-escaped quote, the parsed value is returned in addition to the remaining
    889     /// portion of `val` _after_ the closing quote. The limited verification algorithm is adhered to; thus the
    890     /// _only_ Unicode scalar values that are allowed (and must) be hex-escaped are U+0000 to U+001F inclusively.
    891     /// Similarly only `b'\\'` and `b'"'` are allowed (and must) be escaped with `b'\\'`.
    892     #[expect(unsafe_code, reason = "comment justifies its correctness")] 
    893     #[expect(clippy::arithmetic_side_effects, clippy::indexing_slicing, reason = "comments justify their correctness")]
    894     fn parse_string(val: &[u8]) -> Result<(Cow<'_, str>, &'_ [u8]), CollectedClientDataErr> {
    895         /// Tracks the state of the current Unicode scalar value that is being parsed.
    896         enum State {
    897             /// We are not parsing `'"'`, `'\\'`, or U+0000 to U+001F.
    898             Normal,
    899             /// We just encountered the escape character.
    900             Escape,
    901             /// We just encountered `b"\\u"`.
    902             UnicodeEscape,
    903             /// We just encountered `b"\\u0"`.
    904             UnicodeHex1,
    905             /// We just encountered `b"\\u00"`.
    906             UnicodeHex2,
    907             /// We just encountered `b"\\u000"` or `b"\\u001"`. The contained `u8` is `0` iff the former; otherwise
    908             /// `0x10`.
    909             UnicodeHex3(u8),
    910         }
    911         // We parse this as UTF-8 only at the end iff it is not empty. This contains all the potential Unicode scalar
    912         // values after de-escaping.
    913         let mut utf8 = Vec::new();
    914         // We check for all `u8`s already; thus we might as well check if we encounter a non-ASCII `u8`.
    915         // If we don't, then we can rely on `str::from_utf8_unchecked`.
    916         let mut all_ascii = true;
    917         // This tracks the start index of the next slice to add. We add slices iff we encounter the escape character or
    918         // we return the parsed `Cow` (i.e., encounter an unescaped `b'"'`).
    919         let mut cur_idx = 0;
    920         // The state of the yet-to-be-parsed Unicode scalar value.
    921         let mut state = State::Normal;
    922         for (counter, &b) in val.iter().enumerate() {
    923             match state {
    924                 State::Normal => {
    925                     match b {
    926                         b'"' => {
    927                             if utf8.is_empty() {
    928                                 if all_ascii {
    929                                     // `cur_idx` is 0 or 1. The latter is true iff `val` starts with a
    930                                     // `b'\\'` or `b'"'` but contains no other escaped characters.
    931                                     let s = &val[cur_idx..counter];
    932                                     // SAFETY:
    933                                     // `all_ascii` is `false` iff we encountered any `u8` that was not
    934                                     // an ASCII `u8`; thus we know `s` is valid ASCII which in turn means
    935                                     // it's valid UTF-8.
    936                                     let v = unsafe { str::from_utf8_unchecked(s) };
    937                                     // `val.len() > counter`, so indexing is fine and overflow cannot happen.
    938                                     return Ok((Cow::Borrowed(v), &val[counter + 1..]));
    939                                 }
    940                                 // `cur_idx` is 0 or 1. The latter is true iff `val` starts with a
    941                                 // `b'\\'` or `b'"'` but contains no other escaped characters.
    942                                 return str::from_utf8(&val[cur_idx..counter])
    943                                     .map_err(CollectedClientDataErr::Utf8)
    944                                     // `val.len() > counter`, so indexing is fine and overflow cannot happen.
    945                                     .map(|v| (Cow::Borrowed(v), &val[counter + 1..]));
    946                             }
    947                             // `val.len() > counter && counter >= cur_idx`, so indexing is fine and overflow
    948                             // cannot happen.
    949                             utf8.extend_from_slice(&val[cur_idx..counter]);
    950                             if all_ascii {
    951                                 // SAFETY:
    952                                 // `all_ascii` is `false` iff we encountered any `u8` that was not
    953                                 // an ASCII `u8`; thus we know `utf8` is valid ASCII which in turn means
    954                                 // it's valid UTF-8.
    955                                 let v = unsafe { String::from_utf8_unchecked(utf8) };
    956                                 // `val.len() > counter`, so indexing is fine and overflow cannot happen.
    957                                 return Ok((Cow::Owned(v), &val[counter + 1..]));
    958                             }
    959                             return String::from_utf8(utf8)
    960                                 .map_err(CollectedClientDataErr::Utf8Owned)
    961                                 // `val.len() > counter`, so indexing is fine and overflow cannot happen.
    962                                 .map(|v| (Cow::Owned(v), &val[counter + 1..]));
    963                         }
    964                         b'\\' => {
    965                             // Write the current slice of data.
    966                             utf8.extend_from_slice(&val[cur_idx..counter]);
    967                             state = State::Escape;
    968                         }
    969                         // ASCII is a subset of UTF-8 and this is a subset of ASCII. The code unit that is used for an
    970                         // ASCII Unicode scalar value _never_ appears in multi-code-unit Unicode scalar values; thus we
    971                         // error immediately.
    972                         ..=0x1f => return Err(CollectedClientDataErr::InvalidEscapedString),
    973                         128.. => all_ascii = false,
    974                         _ => (),
    975                     }
    976                 }
    977                 State::Escape => {
    978                     match b {
    979                         b'"' | b'\\' => {
    980                             // We start the next slice here since we need to add it.
    981                             cur_idx = counter;
    982                             state = State::Normal;
    983                         }
    984                         b'u' => {
    985                             state = State::UnicodeEscape;
    986                         }
    987                         _ => {
    988                             return Err(CollectedClientDataErr::InvalidEscapedString);
    989                         }
    990                     }
    991                 }
    992                 State::UnicodeEscape => {
    993                     if b != b'0' {
    994                         return Err(CollectedClientDataErr::InvalidEscapedString);
    995                     }
    996                     state = State::UnicodeHex1;
    997                 }
    998                 State::UnicodeHex1 => {
    999                     if b != b'0' {
   1000                         return Err(CollectedClientDataErr::InvalidEscapedString);
   1001                     }
   1002                     state = State::UnicodeHex2;
   1003                 }
   1004                 State::UnicodeHex2 => {
   1005                     state = State::UnicodeHex3(match b {
   1006                         b'0' => 0,
   1007                         b'1' => 0x10,
   1008                         _ => return Err(CollectedClientDataErr::InvalidEscapedString),
   1009                     });
   1010                 }
   1011                 State::UnicodeHex3(v) => {
   1012                     match b {
   1013                         // Only and all _lowercase_ hex is allowed.
   1014                         b'0'..=b'9' | b'a'..=b'f' => {
   1015                             // When `b < b'a'`, then `b >= b'0'`; and `b'a' > 87`; thus underflow cannot happen.
   1016                             // Note `b'a' - 10 == 87`.
   1017                             utf8.push(v | (b - if b < b'a' { b'0' } else { 87 }));
   1018                             // `counter < val.len()`, so overflow cannot happen.
   1019                             cur_idx = counter + 1;
   1020                             state = State::Normal;
   1021                         }
   1022                         _ => return Err(CollectedClientDataErr::InvalidEscapedString),
   1023                     }
   1024                 }
   1025             }
   1026         }
   1027         // We never encountered an unescaped `b'"'`; thus we could not parse a string.
   1028         Err(CollectedClientDataErr::InvalidObject)
   1029     }
   1030 }
   1031 impl<const R: bool> ClientDataJsonParser for LimitedVerificationParser<R> {
   1032     type Err = CollectedClientDataErr;
   1033     #[expect(clippy::little_endian_bytes, reason = "Challenge::serialize and this need to be consistent across architectures")]
   1034     #[expect(clippy::too_many_lines, reason = "110 lines is fine")]
   1035     fn parse(json: &[u8]) -> Result<CollectedClientData<'_>, Self::Err> {
   1036         // `{"type":"webauthn.<create|get>","challenge":"<22 bytes>","origin":"<bytes>","crossOrigin":<true|false>[,"topOrigin":"<bytes>"][,<anything>]}`.
   1037         /// First portion of `value`.
   1038         const HEADER: &[u8; 18] = br#"{"type":"webauthn."#;
   1039         /// `get`.
   1040         const GET: &[u8; 3] = b"get";
   1041         /// `create`.
   1042         const CREATE: &[u8; 6] = b"create";
   1043         /// Value after type before the start of the base64url-encoded challenge.
   1044         const AFTER_TYPE: &[u8; 15] = br#"","challenge":""#;
   1045         /// Value after challenge before the start of the origin value.
   1046         const AFTER_CHALLENGE: &[u8; 12] = br#"","origin":""#;
   1047         /// Value after origin before the start of the crossOrigin value.
   1048         const AFTER_ORIGIN: &[u8; 15] = br#","crossOrigin":"#;
   1049         /// `true`.
   1050         const TRUE: &[u8; 4] = b"true";
   1051         /// `false`.
   1052         const FALSE: &[u8; 5] = b"false";
   1053         /// Value after crossOrigin before the start of the topOrigin value.
   1054         const AFTER_CROSS: &[u8; 13] = br#""topOrigin":""#;
   1055         json.split_last().ok_or(CollectedClientDataErr::Len).and_then(|(last, last_rem)| {
   1056             if *last == b'}' {
   1057                 last_rem.split_at_checked(HEADER.len()).ok_or(CollectedClientDataErr::Len).and_then(|(header, header_rem)| {
   1058                     if header == HEADER {
   1059                         if R {
   1060                             header_rem.split_at_checked(CREATE.len()).ok_or(CollectedClientDataErr::Len).and_then(|(create, create_rem)| {
   1061                                 if create == CREATE {
   1062                                     Ok(create_rem)
   1063                                 } else {
   1064                                     Err(CollectedClientDataErr::Type)
   1065                                 }
   1066                             })
   1067                         } else {
   1068                             header_rem.split_at_checked(GET.len()).ok_or(CollectedClientDataErr::Len).and_then(|(get, get_rem)| {
   1069                                 if get == GET {
   1070                                     Ok(get_rem)
   1071                                 } else {
   1072                                     Err(CollectedClientDataErr::Type)
   1073                                 }
   1074                             })
   1075                         }.and_then(|type_rem| {
   1076                             type_rem.split_at_checked(AFTER_TYPE.len()).ok_or(CollectedClientDataErr::Len).and_then(|(chall_key, chall_key_rem)| {
   1077                                 if chall_key == AFTER_TYPE {
   1078                                     chall_key_rem.split_at_checked(Challenge::BASE64_LEN).ok_or(CollectedClientDataErr::Len).and_then(|(base64_chall, base64_chall_rem)| {
   1079                                         let mut chall = [0; 16];
   1080                                         base64url_nopad::decode_buffer_exact(base64_chall, chall.as_mut_slice()).map_err(|_e| CollectedClientDataErr::Challenge).and_then(|()| {
   1081                                             base64_chall_rem.split_at_checked(AFTER_CHALLENGE.len()).ok_or(CollectedClientDataErr::Len).and_then(|(origin_key, origin_key_rem)| {
   1082                                                 if origin_key == AFTER_CHALLENGE {
   1083                                                     Self::parse_string(origin_key_rem).and_then(|(origin, origin_rem)| {
   1084                                                         origin_rem.split_at_checked(AFTER_ORIGIN.len()).ok_or(CollectedClientDataErr::Len).and_then(|(cross_key, cross_key_rem)| {
   1085                                                             if cross_key == AFTER_ORIGIN {
   1086                                                                 // `FALSE.len() > TRUE.len()`, so we check for `FALSE` in `and_then`.
   1087                                                                 cross_key_rem.split_at_checked(TRUE.len()).ok_or(CollectedClientDataErr::Len).and_then(|(cross_true, cross_true_rem)| {
   1088                                                                     if cross_true == TRUE {
   1089                                                                         Ok((true, cross_true_rem))
   1090                                                                     } else {
   1091                                                                         cross_key_rem.split_at_checked(FALSE.len()).ok_or(CollectedClientDataErr::Len).and_then(|(cross_false, cross_false_rem)| {
   1092                                                                             if cross_false == FALSE {
   1093                                                                                 Ok((false, cross_false_rem))
   1094                                                                             } else {
   1095                                                                                 Err(CollectedClientDataErr::CrossOrigin)
   1096                                                                             }
   1097                                                                         })
   1098                                                                     }.and_then(|(cross, cross_rem)| {
   1099                                                                         cross_rem.split_first().map_or(Ok((cross, None)), |(comma, comma_rem)| {
   1100                                                                             if *comma == b',' {
   1101                                                                                 comma_rem.split_at_checked(AFTER_CROSS.len()).map_or(Ok((cross, None)), |(top, top_rem)| {
   1102                                                                                     if top == AFTER_CROSS {
   1103                                                                                         if cross {
   1104                                                                                             Self::parse_string(top_rem).and_then(|(top_origin, top_origin_rem)| {
   1105                                                                                                 top_origin_rem.first().map_or(Ok(()), |v| {
   1106                                                                                                     if *v == b',' {
   1107                                                                                                         Ok(())
   1108                                                                                                     } else {
   1109                                                                                                         Err(CollectedClientDataErr::InvalidObject)
   1110                                                                                                     }
   1111                                                                                                 }).and_then(|()| {
   1112                                                                                                     if origin == top_origin {
   1113                                                                                                         Err(CollectedClientDataErr::TopOriginSameAsOrigin)
   1114                                                                                                     } else {
   1115                                                                                                         Ok((true, Some(Origin(top_origin))))
   1116                                                                                                     }
   1117                                                                                                 })
   1118                                                                                             })
   1119                                                                                         } else {
   1120                                                                                             Err(CollectedClientDataErr::TopOriginWithoutCrossOrigin)
   1121                                                                                         }
   1122                                                                                     } else {
   1123                                                                                         Ok((cross, None))
   1124                                                                                     }
   1125                                                                                 })
   1126                                                                             } else {
   1127                                                                                 Err(CollectedClientDataErr::InvalidObject)
   1128                                                                             }
   1129                                                                         }).map(|(cross_origin, top_origin)| CollectedClientData { challenge: SentChallenge(u128::from_le_bytes(chall)), origin: Origin(origin), cross_origin, top_origin, })
   1130                                                                     })
   1131                                                                 })
   1132                                                             } else {
   1133                                                                 Err(CollectedClientDataErr::CrossOriginKey)
   1134                                                             }
   1135                                                         })
   1136                                                     })
   1137                                                 } else {
   1138                                                     Err(CollectedClientDataErr::OriginKey)
   1139                                                 }
   1140                                             })
   1141                                         })
   1142                                     })
   1143                                 } else {
   1144                                     Err(CollectedClientDataErr::ChallengeKey)
   1145                                 }
   1146                             })
   1147                         })
   1148                     } else {
   1149                         Err(CollectedClientDataErr::InvalidStart)
   1150                     }
   1151                 })
   1152             } else {
   1153                 Err(CollectedClientDataErr::InvalidObject)
   1154             }
   1155         })
   1156     }
   1157     #[expect(clippy::arithmetic_side_effects, reason = "comment justifies correctness")]
   1158     #[expect(clippy::little_endian_bytes, reason = "Challenge::serialize and this need to be consistent across architectures")]
   1159     fn get_sent_challenge(json: &[u8]) -> Result<SentChallenge, Self::Err> {
   1160         // Index 39.
   1161         // `{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA"...`.
   1162         // Index 36.
   1163         // `{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA"...`.
   1164         let idx = if R { 39 } else { 36 };
   1165         // This maxes at 39 + 22 = 61; thus overflow is not an issue.
   1166         json.get(idx..idx + Challenge::BASE64_LEN).ok_or(CollectedClientDataErr::Len).and_then(|chall_slice| {
   1167             let mut chall = [0; 16];
   1168             base64url_nopad::decode_buffer_exact(chall_slice, chall.as_mut_slice()).map_err(|_e| CollectedClientDataErr::Challenge).map(|()| {
   1169                 SentChallenge(u128::from_le_bytes(chall))
   1170             })
   1171         })
   1172     }
   1173 }
   1174 /// Authenticator extension outputs;
   1175 pub(super) trait AuthExtOutput {
   1176     /// MUST return `true` iff there is no data.
   1177     fn missing(self) -> bool;
   1178 }
   1179 /// Successful return type from [`FromCbor::from_cbor`].
   1180 struct CborSuccess<'a, T> {
   1181     /// Value parsed from the slice.
   1182     value: T,
   1183     /// Remaining unprocessed data.
   1184     remaining: &'a [u8],
   1185 }
   1186 /// Types that parse
   1187 /// [CTAP2 canonical CBOR encoding form](https://fidoalliance.org/specs/fido-v2.2-rd-20230321/fido-client-to-authenticator-protocol-v2.2-rd-20230321.html#ctap2-canonical-cbor-encoding-form)
   1188 /// data without necessarily consuming all the data.
   1189 ///
   1190 /// The purpose of this `trait` is to allow chains of types to progressively consume `cbor` by passing
   1191 /// [`CborSuccess::remaining`] into the next `FromCbor` type.
   1192 trait FromCbor<'a>: Sized {
   1193     /// Error when conversion fails.
   1194     type Err;
   1195     /// Parses `cbor` into `Self`.
   1196     ///
   1197     /// # Errors
   1198     ///
   1199     /// Errors if `cbor` cannot be parsed into `Self:`.
   1200     fn from_cbor(cbor: &'a [u8]) -> Result<CborSuccess<'a, Self>, Self::Err>;
   1201 }
   1202 /// Error returned from [`A::from_cbor`] `where A: AuthData`.
   1203 enum AuthenticatorDataErr<UpErr, CredData, AuthExt> {
   1204     /// The `slice` had an invalid length.
   1205     Len,
   1206     /// [UP](https://www.w3.org/TR/webauthn-3/#authdata-flags-at) bit was 0.
   1207     UserNotPresent(UpErr),
   1208     /// Bit 1 in [`flags`](https://www.w3.org/TR/webauthn-3/#authdata-flags) is not 0.
   1209     FlagsBit1Not0,
   1210     /// Bit 5 in [`flags`](https://www.w3.org/TR/webauthn-3/#authdata-flags) is not 0.
   1211     FlagsBit5Not0,
   1212     /// [AT](https://www.w3.org/TR/webauthn-3/#authdata-flags-at) bit was 0 during registration or was 1
   1213     /// during authentication.
   1214     AttestedCredentialData,
   1215     /// [BE](https://www.w3.org/TR/webauthn-3/#authdata-flags-be) and
   1216     /// [BS](https://www.w3.org/TR/webauthn-3/#authdata-flags-bs) bits were 0 and 1 respectively.
   1217     BackupWithoutEligibility,
   1218     /// Error returned from [`AttestedCredentialData::from_cbor`].
   1219     AttestedCredential(CredData),
   1220     /// Error returned from [`register::AuthenticatorExtensionOutput::from_cbor`] and
   1221     /// [`auth::AuthenticatorExtensionOutput::from_cbor`].
   1222     AuthenticatorExtension(AuthExt),
   1223     /// [ED](https://www.w3.org/TR/webauthn-3/#authdata-flags-ed) bit was 0, but
   1224     /// [`extensions`](https://www.w3.org/TR/webauthn-3/#authdata-extensions) existed.
   1225     NoExtensionBitWithData,
   1226     /// [ED](https://www.w3.org/TR/webauthn-3/#authdata-flags-ed) bit was 1, but
   1227     /// [`extensions`](https://www.w3.org/TR/webauthn-3/#authdata-extensions) did not exist.
   1228     ExtensionBitWithoutData,
   1229     /// There was trailing data that could not be deserialized.
   1230     TrailingData,
   1231 }
   1232 impl<U, C: Display, A: Display> Display for AuthenticatorDataErr<U, C, A> {
   1233     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
   1234         match *self {
   1235             Self::Len => f.write_str("authenticator data had an invalid length"),
   1236             Self::UserNotPresent(_) => f.write_str("user was not present"),
   1237             Self::FlagsBit1Not0 => f.write_str("flags 1-bit was 1"),
   1238             Self::FlagsBit5Not0 => f.write_str("flags 5-bit was 1"),
   1239             Self::AttestedCredentialData => f.write_str("attested credential data was included during authentication or was not included during registration"),
   1240             Self::BackupWithoutEligibility => {
   1241                 f.write_str("backup state bit was 1 despite backup eligibility being 0")
   1242             }
   1243             Self::AttestedCredential(ref err) => err.fmt(f),
   1244             Self::AuthenticatorExtension(ref err) => err.fmt(f),
   1245             Self::NoExtensionBitWithData => {
   1246                 f.write_str("extension bit was 0 despite extensions existing")
   1247             }
   1248             Self::ExtensionBitWithoutData => {
   1249                 f.write_str("extension bit was 1 despite no extensions existing")
   1250             }
   1251             Self::TrailingData => {
   1252                 f.write_str("slice had trailing data that could not be deserialized")
   1253             }
   1254         }
   1255     }
   1256 }
   1257 impl From<AuthenticatorDataErr<Infallible, AttestedCredentialDataErr, RegAuthExtErr>> for RegAuthDataErr {
   1258     #[inline]
   1259     fn from(value: AuthenticatorDataErr<Infallible, AttestedCredentialDataErr, RegAuthExtErr>) -> Self {
   1260         match value {
   1261             AuthenticatorDataErr::Len => Self::Len,
   1262             AuthenticatorDataErr::UserNotPresent(v) => match v {},
   1263             AuthenticatorDataErr::FlagsBit1Not0 => Self::FlagsBit1Not0,
   1264             AuthenticatorDataErr::FlagsBit5Not0 => Self::FlagsBit5Not0,
   1265             AuthenticatorDataErr::AttestedCredentialData => Self::AttestedCredentialDataNotIncluded,
   1266             AuthenticatorDataErr::BackupWithoutEligibility => Self::BackupWithoutEligibility,
   1267             AuthenticatorDataErr::AttestedCredential(err) => Self::AttestedCredential(err),
   1268             AuthenticatorDataErr::AuthenticatorExtension(err) => Self::AuthenticatorExtension(err),
   1269             AuthenticatorDataErr::NoExtensionBitWithData => Self::NoExtensionBitWithData,
   1270             AuthenticatorDataErr::ExtensionBitWithoutData => Self::ExtensionBitWithoutData,
   1271             AuthenticatorDataErr::TrailingData => Self::TrailingData,
   1272         }
   1273     }
   1274 }
   1275 impl From<AuthenticatorDataErr<(), Infallible, AuthAuthExtErr>> for AuthAuthDataErr {
   1276     #[inline]
   1277     fn from(value: AuthenticatorDataErr<(), Infallible, AuthAuthExtErr>) -> Self {
   1278         match value {
   1279             AuthenticatorDataErr::Len => Self::Len,
   1280             AuthenticatorDataErr::UserNotPresent(()) => Self::UserNotPresent,
   1281             AuthenticatorDataErr::FlagsBit1Not0 => Self::FlagsBit1Not0,
   1282             AuthenticatorDataErr::FlagsBit5Not0 => Self::FlagsBit5Not0,
   1283             AuthenticatorDataErr::AttestedCredentialData => Self::AttestedCredentialDataIncluded,
   1284             AuthenticatorDataErr::AttestedCredential(val) => match val {},
   1285             AuthenticatorDataErr::BackupWithoutEligibility => Self::BackupWithoutEligibility,
   1286             AuthenticatorDataErr::AuthenticatorExtension(err) => Self::AuthenticatorExtension(err),
   1287             AuthenticatorDataErr::NoExtensionBitWithData => Self::NoExtensionBitWithData,
   1288             AuthenticatorDataErr::ExtensionBitWithoutData => Self::ExtensionBitWithoutData,
   1289             AuthenticatorDataErr::TrailingData => Self::TrailingData,
   1290         }
   1291     }
   1292 }
   1293 impl<'a, A> FromCbor<'a> for A
   1294 where
   1295     A: AuthData<'a>,
   1296     A::CredData: FromCbor<'a>,
   1297     A::Ext: FromCbor<'a>,
   1298 {
   1299     type Err = AuthenticatorDataErr<A::UpBitErr, <A::CredData as FromCbor<'a>>::Err, <A::Ext as FromCbor<'a>>::Err>;
   1300     #[expect(clippy::big_endian_bytes, reason = "CBOR integers are in big-endian")]
   1301     fn from_cbor(cbor: &'a [u8]) -> Result<CborSuccess<'a, Self>, Self::Err> {
   1302         /// Length of `signCount`.
   1303         const SIGN_COUNT_LEN: usize = 4;
   1304         /// `UP` bit (i.e., bit 0) set to 1.
   1305         const UP: u8 = 0b0000_0001;
   1306         /// `RFU1` bit (i.e., bit 1) set to 1.
   1307         const RFU1: u8 = UP << 1;
   1308         /// `UV` bit (i.e., bit 2) set to 1.
   1309         const UV: u8 = RFU1 << 1;
   1310         /// `BE` bit (i.e., bit 3) set to 1.
   1311         const BE: u8 = UV << 1;
   1312         /// `BS` bit (i.e., bit 4) set to 1.
   1313         const BS: u8 = BE << 1;
   1314         /// `RFU2` bit (i.e., bit 5) set to 1.
   1315         const RFU2: u8 = BS << 1;
   1316         /// `AT` bit (i.e., bit 6) set to 1.
   1317         const AT: u8 = RFU2 << 1;
   1318         /// `ED` bit (i.e., bit 7) set to 1.
   1319         const ED: u8 = AT << 1;
   1320         cbor.split_at_checked(Sha256::output_size()).ok_or_else(|| AuthenticatorDataErr::Len).and_then(|(rp_id_slice, rp_id_rem)| {
   1321             rp_id_rem.split_first().ok_or_else(|| AuthenticatorDataErr::Len).and_then(|(&flag, flag_rem)| {
   1322                 let user_present = flag & UP == UP;
   1323                 if user_present {
   1324                     Ok(())
   1325                 } else {
   1326                     A::user_is_not_present().map_err(AuthenticatorDataErr::UserNotPresent)   
   1327                 }
   1328                 .and_then(|()| {
   1329                     if flag & RFU1 == 0 {
   1330                         if flag & RFU2 == 0 {
   1331                             let at_bit = A::contains_at_bit();
   1332                             if flag & AT == AT {
   1333                                 if at_bit {
   1334                                     Ok(())
   1335                                 } else {
   1336                                     Err(AuthenticatorDataErr::AttestedCredentialData)
   1337                                 }
   1338                             } else if at_bit {
   1339                                 Err(AuthenticatorDataErr::AttestedCredentialData)
   1340                             } else {
   1341                                 Ok(())
   1342                             }.and_then(|()| {
   1343                                 let bs = flag & BS == BS;
   1344                                 if flag & BE == BE {
   1345                                     if bs {
   1346                                         Ok(Backup::Exists)
   1347                                     } else {
   1348                                         Ok(Backup::Eligible)
   1349                                     }
   1350                                 } else if bs {
   1351                                     Err(AuthenticatorDataErr::BackupWithoutEligibility)
   1352                                 } else {
   1353                                     Ok(Backup::NotEligible)
   1354                                 }
   1355                                 .and_then(|backup| {
   1356                                     flag_rem.split_at_checked(SIGN_COUNT_LEN).ok_or_else(|| AuthenticatorDataErr::Len).and_then(|(count_slice, count_rem)| {
   1357                                         A::CredData::from_cbor(count_rem).map_err(AuthenticatorDataErr::AttestedCredential).and_then(|att_data| {
   1358                                             A::Ext::from_cbor(att_data.remaining).map_err(AuthenticatorDataErr::AuthenticatorExtension).and_then(|ext| {
   1359                                                 if ext.remaining.is_empty() {
   1360                                                     let ed = flag & ED == ED;
   1361                                                     if ext.value.missing() {
   1362                                                         if ed {
   1363                                                             Err(AuthenticatorDataErr::ExtensionBitWithoutData)
   1364                                                         } else {
   1365                                                             Ok(())
   1366                                                         }
   1367                                                     } else if ed {
   1368                                                         Ok(())
   1369                                                     } else {
   1370                                                         Err(AuthenticatorDataErr::NoExtensionBitWithData)
   1371                                                     }.map(|()| {
   1372                                                         let mut sign_count = [0; SIGN_COUNT_LEN];
   1373                                                         sign_count.copy_from_slice(count_slice);
   1374                                                         // `signCount` is in big-endian.
   1375                                                         CborSuccess { value: A::new(rp_id_slice, Flag { user_present, user_verified: flag & UV == UV, backup, }, u32::from_be_bytes(sign_count), att_data.value, ext.value), remaining: ext.remaining, }
   1376                                                     })
   1377                                                 } else {
   1378                                                     Err(AuthenticatorDataErr::TrailingData)
   1379                                                 }
   1380                                             })
   1381                                         })
   1382                                     })
   1383                                 })
   1384                             })
   1385                         } else {
   1386                             Err(AuthenticatorDataErr::FlagsBit5Not0)
   1387                         }
   1388                     } else {
   1389                         Err(AuthenticatorDataErr::FlagsBit1Not0)
   1390                     }
   1391                 })
   1392             })
   1393         })
   1394     }
   1395 }
   1396 /// Data returned by [`AuthDataContainer::from_data`].
   1397 pub(super) struct ParsedAuthData<'a, A> {
   1398     /// The data the CBOR is parsed into.
   1399     data: A,
   1400     /// The raw authenticator data and 32-bytes of trailing data.
   1401     auth_data_and_32_trailing_bytes: &'a [u8],
   1402 }
   1403 /// Error returned by [`AuthResponse::parse_data_and_verify_sig`].
   1404 pub(super) enum AuthRespErr<AuthDataErr> {
   1405     /// Variant returned when parsing
   1406     /// [`clientDataJSON`](https://www.w3.org/TR/webauthn-3/#dom-authenticatorresponse-clientdatajson)
   1407     /// into [`CollectedClientData`] fails.
   1408     CollectedClientData(CollectedClientDataErr),
   1409     /// Variant returned when parsing
   1410     /// [`clientDataJSON`](https://www.w3.org/TR/webauthn-3/#dom-authenticatorresponse-clientdatajson)
   1411     /// in a "relaxed" way into [`CollectedClientData`] fails.
   1412     #[cfg(feature = "serde_relaxed")]
   1413     CollectedClientDataRelaxed(SerdeJsonErr),
   1414     /// Variant returned when parsing [`AuthResponse::Auth`] fails.
   1415     Auth(AuthDataErr),
   1416     /// Variant when the [`CompressedPubKey`] or [`UncompressePubKey`] is not valid.
   1417     PubKey(PubKeyErr),
   1418     /// Variant returned when the signature, if one exists, associated with
   1419     /// [`Self::AuthResponse`] is invalid.
   1420     Signature,
   1421 }
   1422 impl<A: Display> Display for AuthRespErr<A> {
   1423     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
   1424         match *self {
   1425             Self::CollectedClientData(ref err) => write!(f, "CollectedClientData could not be parsed: {err}"),
   1426             #[cfg(feature = "serde_relaxed")]
   1427             Self::CollectedClientDataRelaxed(ref err) => write!(f, "CollectedClientData could not be parsed: {err}"),
   1428             Self::Auth(ref err) => write!(f, "auth data could not be parsed: {err}"),
   1429             Self::PubKey(err) => err.fmt(f),
   1430             Self::Signature => f.write_str("the signature over the authenticator data and CollectedClientData could not be verified"),
   1431         }
   1432     }
   1433 }
   1434 impl From<AuthRespErr<AttestationObjectErr>> for RegCeremonyErr {
   1435     #[inline]
   1436     fn from(value: AuthRespErr<AttestationObjectErr>) -> Self {
   1437         match value {
   1438             AuthRespErr::CollectedClientData(err) => Self::CollectedClientData(err),
   1439             #[cfg(feature = "serde_relaxed")]
   1440             AuthRespErr::CollectedClientDataRelaxed(err) => Self::CollectedClientDataRelaxed(err),
   1441             AuthRespErr::Auth(err) => Self::AttestationObject(err),
   1442             AuthRespErr::PubKey(err) => Self::PubKey(err),
   1443             AuthRespErr::Signature => Self::AttestationSignature,
   1444         }
   1445     }
   1446 }
   1447 impl From<AuthRespErr<AuthAuthDataErr>> for AuthCeremonyErr {
   1448     #[inline]
   1449     fn from(value: AuthRespErr<AuthAuthDataErr>) -> Self {
   1450         match value {
   1451             AuthRespErr::CollectedClientData(err) => Self::CollectedClientData(err),
   1452             #[cfg(feature = "serde_relaxed")]
   1453             AuthRespErr::CollectedClientDataRelaxed(err) => Self::CollectedClientDataRelaxed(err),
   1454             AuthRespErr::Auth(err) => Self::AuthenticatorData(err),
   1455             AuthRespErr::PubKey(err) => Self::PubKey(err),
   1456             AuthRespErr::Signature => Self::AssertionSignature,
   1457         }
   1458     }
   1459 }
   1460 /// [Authenticator data](https://www.w3.org/TR/webauthn-3/#authenticator-data)
   1461 /// container.
   1462 ///
   1463 /// Note [`Self::Auth`] may be `Self`.
   1464 pub(super) trait AuthDataContainer<'a>: Sized {
   1465     /// [Authenticator data](https://www.w3.org/TR/webauthn-3/#authenticator-data).
   1466     type Auth: AuthData<'a>;
   1467     /// Error returned from [`Self::from_data`].
   1468     type Err;
   1469     /// Converts `data` into [`ParsedAuthData`].
   1470     ///
   1471     /// # Errors
   1472     ///
   1473     /// Errors iff `data` cannot be converted into `ParsedAuthData`.
   1474     fn from_data(data: &'a [u8]) -> Result<ParsedAuthData<'a, Self>, Self::Err>;
   1475     /// Returns the contained
   1476     /// [authenticator data](https://www.w3.org/TR/webauthn-3/#authenticator-data).
   1477     fn authenticator_data(&self) -> &Self::Auth;
   1478 }
   1479 /// [`AuthenticatorResponse`](https://www.w3.org/TR/webauthn-3/#authenticatorresponse).
   1480 pub(super) trait AuthResponse {
   1481     /// [Attestation object](https://www.w3.org/TR/webauthn-3/#attestation-object) or
   1482     /// [authenticator data](https://www.w3.org/TR/webauthn-3/#authenticator-data).
   1483     type Auth<'a>: AuthDataContainer<'a> where Self: 'a;
   1484     /// Public key to use to verify the contained signature.
   1485     type CredKey<'a>;
   1486     /// Parses
   1487     /// [`clientDataJSON`](https://www.w3.org/TR/webauthn-3/#dom-authenticatorresponse-clientdatajson)
   1488     /// based on `RELAXED` and [`Self::Auth`] via [`AuthDataContainer::from_data`] in addition to
   1489     /// verifying any possible signature over the concatenation of the raw
   1490     /// [`AuthDataContainer::Auth`] and `clientDataJSON` using `key` or the contained
   1491     /// public key if one exists. If `Self` contains a public key and should not be passed one, then it should set
   1492     /// [`Self::CredKey`] to `()`.
   1493     ///
   1494     /// # Errors
   1495     ///
   1496     /// Errors iff parsing `clientDataJSON` errors, [`AuthDataContainer::from_data`] does, or the signature
   1497     /// is invalid.
   1498     ///
   1499     /// # Panics
   1500     ///
   1501     /// `panic`s iff `relaxed` and `serde_relaxed` is not enabled.
   1502     #[expect(
   1503         clippy::type_complexity,
   1504         reason = "type aliases with bounds are even more problematic at least until lazy_type_alias is stable"
   1505     )]
   1506     fn parse_data_and_verify_sig(&self, key: Self::CredKey<'_>, relaxed: bool) -> Result<(CollectedClientData<'_>, Self::Auth<'_>), AuthRespErr<<Self::Auth<'_> as AuthDataContainer<'_>>::Err>>;
   1507 }
   1508 /// Ceremony response (i.e., [`PublicKeyCredential`](https://www.w3.org/TR/webauthn-3/#publickeycredential)).
   1509 pub(super) trait Response {
   1510     /// [`AuthenticatorResponse`](https://www.w3.org/TR/webauthn-3/#authenticatorresponse).
   1511     type Auth: AuthResponse;
   1512     /// [`response`](https://www.w3.org/TR/webauthn-3/#dom-publickeycredential-response).
   1513     fn auth(&self) -> &Self::Auth;
   1514 }
   1515 /// Error returned from [`Ceremony::partial_validate`].
   1516 pub(super) enum CeremonyErr<AuthDataErr> {
   1517     /// Timeout occurred.
   1518     Timeout,
   1519     /// Read [`AuthRespErr`] for information.
   1520     AuthResp(AuthRespErr<AuthDataErr>),
   1521     /// Origin did not validate.
   1522     OriginMismatch,
   1523     /// Cross origin was `true` but was not allowed to be.
   1524     CrossOrigin,
   1525     /// Top origin did not validate.
   1526     TopOriginMismatch,
   1527     /// Challenges don't match.
   1528     ChallengeMismatch,
   1529     /// `rpIdHash` does not match the SHA-256 hash of the [`RpId`].
   1530     RpIdHashMismatch,
   1531     /// User was not verified despite being required to.
   1532     UserNotVerified,
   1533     /// [`Backup::NotEligible`] was not sent back despite [`BackupReq::NotEligible`].
   1534     BackupEligible,
   1535     /// [`Backup::NotEligible`] was sent back despite [`BackupReq::Eligible`].
   1536     BackupNotEligible,
   1537     /// [`Backup::Eligible`] was not sent back despite [`BackupReq::EligibleNoteExists`].
   1538     BackupExists,
   1539     /// [`Backup::Exists`] was not sent back despite [`BackupReq::Exists`].
   1540     BackupDoesNotExist,
   1541 }
   1542 impl<A: Display> Display for CeremonyErr<A> {
   1543     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
   1544         match *self {
   1545             Self::Timeout => f.write_str("ceremony timed out"),
   1546             Self::AuthResp(ref err) => err.fmt(f),
   1547             Self::OriginMismatch => {
   1548                 f.write_str("the origin sent from the client is not an allowed origin")
   1549             }
   1550             Self::CrossOrigin => {
   1551                 f.write_str("cross origin was from the client, but it is not allowed")
   1552             }
   1553             Self::TopOriginMismatch => {
   1554                 f.write_str("the top origin sent from the client is not an allowed top origin")
   1555             }
   1556             Self::ChallengeMismatch => f.write_str(
   1557                 "the challenge sent to the client does not match the challenge sent back",
   1558             ),
   1559             Self::RpIdHashMismatch => f.write_str(
   1560                 "the SHA-256 hash of the RP ID doesn't match the hash sent from the client",
   1561             ),
   1562             Self::UserNotVerified => f.write_str("user was not verified despite being required to"),
   1563             Self::BackupEligible => f.write_str("credential is eligible to be backed up despite requiring that it not be"),
   1564             Self::BackupNotEligible => f.write_str("credential is not eligible to be backed up despite requiring that it be"),
   1565             Self::BackupExists => f.write_str("credential backup exists despite requiring that a backup not exist"),
   1566             Self::BackupDoesNotExist => f.write_str("credential backup does not exist despite requiring that a backup exist"),
   1567         }
   1568     }
   1569 }
   1570 impl From<CeremonyErr<AttestationObjectErr>> for RegCeremonyErr {
   1571     #[inline]
   1572     fn from(value: CeremonyErr<AttestationObjectErr>) -> Self {
   1573         match value {
   1574             CeremonyErr::Timeout => Self::Timeout,
   1575             CeremonyErr::AuthResp(err) => err.into(),
   1576             CeremonyErr::OriginMismatch => Self::OriginMismatch,
   1577             CeremonyErr::CrossOrigin => Self::CrossOrigin,
   1578             CeremonyErr::TopOriginMismatch => Self::TopOriginMismatch,
   1579             CeremonyErr::ChallengeMismatch => Self::ChallengeMismatch,
   1580             CeremonyErr::RpIdHashMismatch => Self::RpIdHashMismatch,
   1581             CeremonyErr::UserNotVerified => Self::UserNotVerified,
   1582             CeremonyErr::BackupEligible => Self::BackupEligible,
   1583             CeremonyErr::BackupNotEligible => Self::BackupNotEligible,
   1584             CeremonyErr::BackupExists => Self::BackupExists,
   1585             CeremonyErr::BackupDoesNotExist => Self::BackupDoesNotExist,
   1586         }
   1587     }
   1588 }
   1589 impl From<CeremonyErr<AuthAuthDataErr>> for AuthCeremonyErr {
   1590     #[inline]
   1591     fn from(value: CeremonyErr<AuthAuthDataErr>) -> Self {
   1592         match value {
   1593             CeremonyErr::Timeout => Self::Timeout,
   1594             CeremonyErr::AuthResp(err) => err.into(),
   1595             CeremonyErr::OriginMismatch => Self::OriginMismatch,
   1596             CeremonyErr::CrossOrigin => Self::CrossOrigin,
   1597             CeremonyErr::TopOriginMismatch => Self::TopOriginMismatch,
   1598             CeremonyErr::ChallengeMismatch => Self::ChallengeMismatch,
   1599             CeremonyErr::RpIdHashMismatch => Self::RpIdHashMismatch,
   1600             CeremonyErr::UserNotVerified => Self::UserNotVerified,
   1601             CeremonyErr::BackupEligible => Self::BackupEligible,
   1602             CeremonyErr::BackupNotEligible => Self::BackupNotEligible,
   1603             CeremonyErr::BackupExists => Self::BackupExists,
   1604             CeremonyErr::BackupDoesNotExist => Self::BackupDoesNotExist,
   1605         }
   1606     }
   1607 }
   1608 /// [`AllAcceptedCredentialsOptions`](https://www.w3.org/TR/webauthn-3/#dictdef-allacceptedcredentialsoptions).
   1609 ///
   1610 /// This can be sent to _an already authenticated user_ to inform what credentials are currently registered.
   1611 /// This can be useful when a user deletes credentials on the RP's side but does not do so on the authenticator.
   1612 /// When the client forwards this response to the authenticator, it can remove all credentials that don't have
   1613 /// a [`CredentialId`] in [`Self::all_accepted_credential_ids`].
   1614 #[derive(Debug)]
   1615 pub struct AllAcceptedCredentialsOptions<'rp, 'user, const USER_LEN: usize> {
   1616     /// [`rpId`](https://www.w3.org/TR/webauthn-3/#dictdef-allacceptedcredentialsoptions-rpid).
   1617     pub rp_id: &'rp RpId,
   1618     /// [`userId`](https://www.w3.org/TR/webauthn-3/#dictdef-allacceptedcredentialsoptions-userid).
   1619     pub user_id: &'user UserHandle<USER_LEN>,
   1620     /// [`allAcceptedCredentialIds`](https://www.w3.org/TR/webauthn-3/#dictdef-allacceptedcredentialsoptions-allacceptedcredentialids).
   1621     pub all_accepted_credential_ids: Vec<CredentialId<Vec<u8>>>,
   1622 }
   1623 /// [`CurrentUserDetailsOptions`](https://www.w3.org/TR/webauthn-3/#dictdef-currentuserdetailsoptions).
   1624 ///
   1625 /// This can be sent to _an already authenticated user_ to inform the user information.
   1626 /// This can be useful when a user updates their user information on the RP's side but does not do so on the authenticator.
   1627 /// When the client forwards this response to the authenticator, it can update the user info for the associated credential.
   1628 #[derive(Debug)]
   1629 pub struct CurrentUserDetailsOptions<'rp_id, 'name, 'display_name, 'id, const LEN: usize> {
   1630     /// [`rpId`](https://www.w3.org/TR/webauthn-3/#dictdef-currentuserdetailsoptions-rpid).
   1631     pub rp_id: &'rp_id RpId,
   1632     /// [`userId`](https://www.w3.org/TR/webauthn-3/#dictdef-currentuserdetailsoptions-userid),
   1633     /// [`name`](https://www.w3.org/TR/webauthn-3/#dictdef-currentuserdetailsoptions-name), and
   1634     /// [`displayName`](https://www.w3.org/TR/webauthn-3/#dictdef-currentuserdetailsoptions-displayname).
   1635     pub user: PublicKeyCredentialUserEntity<'name, 'display_name, 'id, LEN>,
   1636 }
   1637 /// [`hmac-secret`](https://fidoalliance.org/specs/fido-v2.2-rd-20230321/fido-client-to-authenticator-protocol-v2.2-rd-20230321.html#sctn-hmac-secret-extension)
   1638 /// during authentication and
   1639 /// [`hmac-secret-mc`](https://fidoalliance.org/specs/fido-v2.2-ps-20250228/fido-client-to-authenticator-protocol-v2.2-ps-20250228.html#sctn-hmac-secret-make-cred-extension)
   1640 /// during registration.
   1641 ///
   1642 /// `REG` iff `hmac-secret-mc`.
   1643 enum HmacSecretGet<const REG: bool> {
   1644     /// No `hmac-secret` response.
   1645     None,
   1646     /// One encrypted `hmac-secret`.
   1647     One,
   1648     /// Two encrypted `hmac-secret`s.
   1649     Two,
   1650 }
   1651 /// Error returned by [`HmacSecretGet::from_cbor`]
   1652 enum HmacSecretGetErr {
   1653     /// Error related to the length of the CBOR input.
   1654     Len,
   1655     /// Error related to the type of the CBOR key.
   1656     Type,
   1657     /// Error related to the value of the CBOR value.
   1658     Value,
   1659 }
   1660 impl<const REG: bool> FromCbor<'_> for HmacSecretGet<REG> {
   1661     type Err = HmacSecretGetErr;
   1662     fn from_cbor(cbor: &[u8]) -> Result<CborSuccess<'_, Self>, Self::Err> {
   1663         /// AES block size.
   1664         const AES_BLOCK_SIZE: usize = 16;
   1665         /// HMAC-SHA-256 output length.
   1666         const HMAC_SHA_256_LEN: usize = 32;
   1667         /// Length of two HMAC-SHA-256 outputs concatenated together.
   1668         const TWO_HMAC_SHA_256_LEN: usize = HMAC_SHA_256_LEN << 1;
   1669         // We need the smallest multiple of `AES_BLOCK_SIZE` that
   1670         // is strictly greater than `HMAC_SHA_256_LEN`.
   1671         /// AES-256 output length on a 32-byte input.
   1672         #[expect(
   1673             clippy::integer_division_remainder_used,
   1674             reason = "doesn't need to be constant time"
   1675         )]
   1676         const ONE_SECRET_LEN: usize =
   1677             HMAC_SHA_256_LEN + (AES_BLOCK_SIZE - (HMAC_SHA_256_LEN % AES_BLOCK_SIZE));
   1678         // We need the smallest multiple of `AES_BLOCK_SIZE` that
   1679         // is strictly greater than `TWO_HMAC_SHA_256_LEN`.
   1680         /// AES-256 output length on a 64-byte input.
   1681         #[expect(
   1682             clippy::integer_division_remainder_used,
   1683             reason = "doesn't need to be constant time"
   1684         )]
   1685         const TWO_SECRET_LEN: usize =
   1686             TWO_HMAC_SHA_256_LEN + (AES_BLOCK_SIZE - (TWO_HMAC_SHA_256_LEN % AES_BLOCK_SIZE));
   1687         /// `hmac-secret-mc`.
   1688         ///
   1689         /// This is the key iff `REG`.
   1690         const KEY: [u8; 15] = [
   1691             cbor::TEXT_14,
   1692             b'h',
   1693             b'm',
   1694             b'a',
   1695             b'c',
   1696             b'-',
   1697             b's',
   1698             b'e',
   1699             b'c',
   1700             b'r',
   1701             b'e',
   1702             b't',
   1703             b'-',
   1704             b'm',
   1705             b'c',
   1706         ];
   1707         /// Helper that unifies `HmacSecretGet`.
   1708         enum CborVal<'a> {
   1709             /// Extension does not exist with remaining payload
   1710             Success,
   1711             /// Extension exists with remaining payload.
   1712             Continue(&'a [u8]),
   1713         }
   1714         if REG {
   1715             cbor.split_at_checked(KEY.len()).map_or(
   1716                 Ok(CborVal::Success),
   1717                 |(key, key_rem)| {
   1718                     if key == KEY {
   1719                         Ok(CborVal::Continue(key_rem))
   1720                     } else {
   1721                         Ok(CborVal::Success)
   1722                     }
   1723                 }
   1724             )
   1725         } else {
   1726             cbor.split_at_checked(cbor::HMAC_SECRET.len()).map_or(
   1727                 Ok(CborVal::Success),
   1728                 |(key, key_rem)| {
   1729                     if key == cbor::HMAC_SECRET {
   1730                         Ok(CborVal::Continue(key_rem))
   1731                     } else {
   1732                         Ok(CborVal::Success)
   1733                     }
   1734                 }
   1735             )
   1736         }.and_then(|cbor_val| {
   1737             match cbor_val {
   1738                 CborVal::Success => Ok(CborSuccess { value: Self::None, remaining: cbor, }),
   1739                 CborVal::Continue(key_rem) => {
   1740                     key_rem
   1741                         .split_first()
   1742                         .ok_or(HmacSecretGetErr::Len)
   1743                         .and_then(|(bytes, bytes_rem)| {
   1744                             if *bytes == cbor::BYTES_INFO_24 {
   1745                                 bytes_rem
   1746                                     .split_first()
   1747                                     .ok_or(HmacSecretGetErr::Len)
   1748                                     .and_then(|(&len, len_rem)| {
   1749                                         len_rem.split_at_checked(usize::from(len)).ok_or(HmacSecretGetErr::Len).and_then(|(_, remaining)| {
   1750                                             match usize::from(len) {
   1751                                                 ONE_SECRET_LEN => {
   1752                                                     Ok(CborSuccess {
   1753                                                         value: Self::One,
   1754                                                         remaining,
   1755                                                     })
   1756                                                 }
   1757                                                 TWO_SECRET_LEN => {
   1758                                                     Ok(CborSuccess {
   1759                                                         value: Self::Two,
   1760                                                         remaining,
   1761                                                     })
   1762                                                 }
   1763                                                 _ => Err(HmacSecretGetErr::Value),
   1764                                             }
   1765                                         })
   1766                                     })
   1767                             } else {
   1768                                 Err(HmacSecretGetErr::Type)
   1769                             }
   1770                         })
   1771                 }
   1772             }
   1773         })
   1774     }
   1775 }
   1776 #[cfg(test)]
   1777 mod tests {
   1778     use super::{CollectedClientDataErr, ClientDataJsonParser as _, LimitedVerificationParser};
   1779     #[test]
   1780     fn parse_string() {
   1781         assert!(LimitedVerificationParser::<true>::parse_string(br#"abc""#)
   1782             .is_ok_and(|tup| { tup.0 == "abc" && tup.1 == b"" }));
   1783         assert!(LimitedVerificationParser::<false>::parse_string(br#"abc"23"#)
   1784             .is_ok_and(|tup| { tup.0 == "abc" && tup.1 == b"23" }));
   1785         assert!(LimitedVerificationParser::<true>::parse_string(br#"ab\"c"23"#)
   1786             .is_ok_and(|tup| { tup.0 == r#"ab"c"# && tup.1 == b"23" }));
   1787         assert!(LimitedVerificationParser::<false>::parse_string(br#"ab\\c"23"#)
   1788             .is_ok_and(|tup| { tup.0 == r"ab\c" && tup.1 == b"23" }));
   1789         assert!(LimitedVerificationParser::<true>::parse_string(br#"ab\u001fc"23"#)
   1790             .is_ok_and(|tup| { tup.0 == "ab\u{001f}c" && tup.1 == b"23" }));
   1791         assert!(LimitedVerificationParser::<false>::parse_string(br#"ab\u000dc"23"#)
   1792             .is_ok_and(|tup| { tup.0 == "ab\u{000d}c" && tup.1 == b"23" }));
   1793         assert!(
   1794             LimitedVerificationParser::<true>::parse_string(b"\\\\\\\\\\\\a\\\\\\\\a\\\\\"").is_ok_and(|tup| {
   1795                 tup.0 == "\\\\\\a\\\\a\\" && tup.1.is_empty()
   1796             })
   1797         );
   1798         assert!(
   1799             LimitedVerificationParser::<false>::parse_string(b"\\\\\\\\\\a\\\\\\\\a\\\\\"").is_err_and(
   1800                 |e| matches!(e, CollectedClientDataErr::InvalidEscapedString),
   1801             )
   1802         );
   1803         assert!(LimitedVerificationParser::<true>::parse_string(br#"ab\u0020c"23"#).is_err_and(
   1804             |err| matches!(err, CollectedClientDataErr::InvalidEscapedString),
   1805         ));
   1806         assert!(LimitedVerificationParser::<false>::parse_string(br#"ab\ac"23"#).is_err_and(
   1807             |err| matches!(err, CollectedClientDataErr::InvalidEscapedString),
   1808         ));
   1809         assert!(LimitedVerificationParser::<true>::parse_string(br#"ab\""#).is_err_and(
   1810             |err| matches!(err, CollectedClientDataErr::InvalidObject),
   1811         ));
   1812         assert!(LimitedVerificationParser::<false>::parse_string(br#"ab\u001Fc"23"#).is_err_and(
   1813             |err| matches!(err, CollectedClientDataErr::InvalidEscapedString),
   1814         ));
   1815         assert!(LimitedVerificationParser::<true>::parse_string([0, b'"'].as_slice()).is_err_and(
   1816             |err| matches!(err, CollectedClientDataErr::InvalidEscapedString),
   1817         ));
   1818         assert!(LimitedVerificationParser::<false>::parse_string([b'a', 255, b'"'].as_slice())
   1819             .is_err_and(|err| matches!(err, CollectedClientDataErr::Utf8(_))));
   1820         assert!(LimitedVerificationParser::<true>::parse_string([b'a', b'"', 255].as_slice()).is_ok_and(|tup| tup.0 == "a" && tup.1 == [255]));
   1821         assert!(
   1822             LimitedVerificationParser::<false>::parse_string(br#"""#).is_ok_and(|tup| tup.0.is_empty() && tup.1.is_empty())
   1823         );
   1824     }
   1825     #[expect(clippy::cognitive_complexity, reason = "a lot of things to test")]
   1826     #[test]
   1827     fn c_data_json() {
   1828         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && !val.cross_origin && val.top_origin.is_none()));
   1829         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false,{}}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && !val.cross_origin && val.top_origin.is_none()));
   1830         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && val.cross_origin && val.top_origin.is_none()));
   1831         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true,"topOrigin":"bob"}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && val.cross_origin && val.top_origin.is_some_and(|v| v == "bob")));
   1832         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true,"topOrigin":"bob",a}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && val.cross_origin && val.top_origin.is_some_and(|v| v == "bob")));
   1833         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true,"topOrigin":"bob"a}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidObject)));
   1834         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false,"topOrigin":""}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::TopOriginWithoutCrossOrigin)));
   1835         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false,"topOrigin":""}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::Challenge)));
   1836         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0.is_empty() && !val.cross_origin && val.top_origin.is_none()));
   1837         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::Type)));
   1838         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create", "challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::ChallengeKey)));
   1839         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::OriginKey)));
   1840         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\\e.com","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://exampl\\e.com" && !val.cross_origin && val.top_origin.is_none()));
   1841         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\"e.com","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://exampl\"e.com" && !val.cross_origin && val.top_origin.is_none()));
   1842         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\u0013e.com","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://exampl\u{0013}e.com" && !val.cross_origin && val.top_origin.is_none()));
   1843         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\3e.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidEscapedString)));
   1844         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\e.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidEscapedString)));
   1845         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\u0020.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidEscapedString)));
   1846         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\u000A.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidEscapedString)));
   1847         assert!(LimitedVerificationParser::<true>::parse([].as_slice())
   1848             .is_err_and(|e| matches!(e, CollectedClientDataErr::Len)));
   1849         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"abc","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidStart)));
   1850         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidObject)));
   1851         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","crossOrigin":false,"origin":"example.com"}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::OriginKey)));
   1852         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","topOrigin":"bob","crossOrigin":true}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::CrossOriginKey)));
   1853         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":"abc"}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::CrossOrigin)));
   1854         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true"a}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidObject)));
   1855         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true","topOrigin":"https://abc.com"a}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidObject)));
   1856         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && !val.cross_origin && val.top_origin.is_none()));
   1857         assert!(LimitedVerificationParser::<false>::parse(b"{\"type\":\"webauthn.get\",\"challenge\":\"AAAAAAAAAAAAAAAAAAAAAA\",\"origin\":\"https://example.com\",\"crossOrigin\":false,\xff}".as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && !val.cross_origin && val.top_origin.is_none()));
   1858         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && val.cross_origin && val.top_origin.is_none()));
   1859         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true,"topOrigin":"bob"}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && val.cross_origin && val.top_origin.is_some_and(|v| v == "bob")));
   1860         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false,"topOrigin":""}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::TopOriginWithoutCrossOrigin)));
   1861         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false,"topOrigin":""}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::Challenge)));
   1862         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0.is_empty() && !val.cross_origin && val.top_origin.is_none()));
   1863         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::Type)));
   1864         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get", "challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::ChallengeKey)));
   1865         assert!(LimitedVerificationParser::<false>::parse(
   1866             br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","crossOrigin":false}"#
   1867                 .as_slice()
   1868         )
   1869         .is_err_and(|e| matches!(e, CollectedClientDataErr::OriginKey)));
   1870         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\\e.com","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://exampl\\e.com" && !val.cross_origin && val.top_origin.is_none()));
   1871         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\"e.com","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://exampl\"e.com" && !val.cross_origin && val.top_origin.is_none()));
   1872         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\u0013e.com","crossOrigin":false}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://exampl\u{0013}e.com" && !val.cross_origin && val.top_origin.is_none()));
   1873         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\3e.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidEscapedString)));
   1874         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\e.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidEscapedString)));
   1875         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\u0020.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidEscapedString)));
   1876         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://exampl\u000A.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidEscapedString)));
   1877         assert!(LimitedVerificationParser::<false>::parse([].as_slice())
   1878             .is_err_and(|e| matches!(e, CollectedClientDataErr::Len)));
   1879         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"abc","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidStart)));
   1880         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidObject)));
   1881         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","crossOrigin":false,"origin":"example.com"}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::OriginKey)));
   1882         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","topOrigin":"bob","crossOrigin":true}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::CrossOriginKey)));
   1883         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":"abc"}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::CrossOrigin)));
   1884         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true"a}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::InvalidObject)));
   1885         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":true,"topOrigin":"https://example.com"}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::TopOriginSameAsOrigin)));
   1886         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create","challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false,"foo":true}"#.as_slice()).is_ok_and(|val| val.challenge.0 == 0 && val.origin.0 == "https://example.com" && !val.cross_origin && val.top_origin.is_none()));
   1887         assert!(LimitedVerificationParser::<false>::parse(br#"{"type":"webauthn.get","challengE":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossOrigin":false,"foo":true}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::ChallengeKey)));
   1888         assert!(LimitedVerificationParser::<true>::parse(br#"{"type":"webauthn.create"challenge":"AAAAAAAAAAAAAAAAAAAAAA","origin":"https://example.com","crossorigin":false,"foo":true}"#.as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::ChallengeKey)));
   1889     }
   1890     #[test]
   1891     fn c_data_challenge() {
   1892         assert!(LimitedVerificationParser::<false>::get_sent_challenge([].as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::Len)));
   1893         assert!(LimitedVerificationParser::<true>::get_sent_challenge([].as_slice()).is_err_and(|e| matches!(e, CollectedClientDataErr::Len)));
   1894         assert!(LimitedVerificationParser::<true>::get_sent_challenge(b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBB").is_err_and(|e| matches!(e, CollectedClientDataErr::Challenge)));
   1895         assert!(LimitedVerificationParser::<false>::get_sent_challenge(b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBB").is_err_and(|e| matches!(e, CollectedClientDataErr::Challenge)));
   1896         assert!(LimitedVerificationParser::<true>::get_sent_challenge(b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA".as_slice()).is_ok_and(|c| c.0 == 0));
   1897         assert!(LimitedVerificationParser::<false>::get_sent_challenge(b"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA".as_slice()).is_ok_and(|c| c.0 == 0));
   1898     }
   1899 }