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Smaller keyhandle length #8

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Smaller keyhandle length #8

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2 changes: 2 additions & 0 deletions src/credential.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -89,7 +89,9 @@ pub struct CredentialData {
pub key: Key,

// extensions
#[serde(skip_serializing_if = "Option::is_none")]
pub hmac_secret: Option<bool>,
#[serde(skip_serializing_if = "Option::is_none")]
pub cred_protect: Option<CredentialProtectionPolicy>,

// TODO: add `sig_counter: Option<CounterId>`,
Expand Down
58 changes: 42 additions & 16 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,10 @@ use ctap_types::{
Result as U2fResult,
Error as U2fError,
},
webauthn::{
PublicKeyCredentialRpEntity,
PublicKeyCredentialUserEntity
}
};

use littlefs2::path::{Path, PathBuf};
Expand Down Expand Up @@ -1835,31 +1839,53 @@ where UP: UserPresence,
let nonce = syscall!(self.trussed.random_bytes(12)).bytes.as_slice().try_into().unwrap();
info!("nonce = {:?}", &nonce);

let credential = Credential::new(
credential::CtapVersion::Fido21Pre,
&parameters.rp,
&parameters.user,
algorithm as i32,
key_parameter,
self.state.persistent.timestamp(&mut self.trussed)?,
hmac_secret_requested.clone(),
cred_protect_requested,
nonce,
);

// info!("made credential {:?}", &credential);

// 12.b generate credential ID { = AEAD(Serialize(Credential)) }
let kek = self.state.persistent.key_encryption_key(&mut self.trussed)?;
let credential_id = credential.id_using_hash(&mut self.trussed, kek, &rp_id_hash)?;

// store it.
// TODO: overwrite, error handling with KeyStoreFull

let serialized_credential = credential.serialize()?;
// Introduce smaller Credential struct for ID, with extra metadata removed. This ensures
// ID will stay below 255 bytes.
let credential_thin = Credential::new(
credential::CtapVersion::Fido21Pre,
&PublicKeyCredentialRpEntity{
id: parameters.rp.id.clone(),
name: None,
url: None
},
&PublicKeyCredentialUserEntity {
id: parameters.user.id.clone(),
icon: None,
name: None,
display_name: None
},
algorithm as i32,
key_parameter.clone(),
self.state.persistent.timestamp(&mut self.trussed)?,
None,
None,
nonce,
);

let credential_id = credential_thin.id_using_hash(&mut self.trussed, kek, &rp_id_hash)?;

if rk_requested {
// Create full credential for the Resident Key usage, and store it in local memory.
let credential = Credential::new(
credential::CtapVersion::Fido21Pre,
&parameters.rp,
&parameters.user,
algorithm as i32,
key_parameter,
self.state.persistent.timestamp(&mut self.trussed)?,
hmac_secret_requested.clone(),
cred_protect_requested,
nonce,
);
// info!("made credential {:?}", &credential);
let serialized_credential = credential.serialize()?;

// first delete any other RK cred with same RP + UserId if there is one.
self.delete_resident_key_by_user_id(&rp_id_hash, &credential.user.id).ok();

Expand Down