diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/u2f.h | 23 | ||||
| -rw-r--r-- | include/u2f_impl.h | 15 |
2 files changed, 33 insertions, 5 deletions
diff --git a/include/u2f.h b/include/u2f.h index 61b9677185..6680ef5300 100644 --- a/include/u2f.h +++ b/include/u2f.h @@ -31,6 +31,8 @@ extern "C" { #define U2F_MAX_ATTEST_SIZE 256 /* Size of largest blob to sign */ #define U2F_P256_SIZE 32 +#define SHA256_DIGEST_SIZE 32 + #define ENC_SIZE(x) ((x + 7) & 0xfff8) /* EC (uncompressed) point */ @@ -53,15 +55,24 @@ struct u2f_ec_point { #define U2F_KH_VERSION_1 0x01 +#define U2F_AUTHORIZATION_SALT_SIZE 16 + struct u2f_key_handle { uint8_t origin_seed[U2F_P256_SIZE]; - uint8_t hmac[U2F_P256_SIZE]; + uint8_t hmac[SHA256_DIGEST_SIZE]; }; -struct u2f_versioned_key_handle { +struct u2f_versioned_key_handle_header { uint8_t version; uint8_t origin_seed[U2F_P256_SIZE]; - uint8_t hmac[U2F_P256_SIZE]; + uint8_t kh_hmac[SHA256_DIGEST_SIZE]; +}; + +struct u2f_versioned_key_handle { + struct u2f_versioned_key_handle_header header; + /* Optionally checked in u2f_sign. */ + uint8_t authorization_salt[U2F_AUTHORIZATION_SALT_SIZE]; + uint8_t authorization_hmac[SHA256_DIGEST_SIZE]; }; /* TODO(louiscollard): Add Descriptions. */ @@ -70,6 +81,11 @@ struct u2f_generate_req { uint8_t appId[U2F_APPID_SIZE]; /* Application id */ uint8_t userSecret[U2F_P256_SIZE]; uint8_t flags; + /* + * If generating versioned KH, derive an hmac from it and append to + * the key handle. Otherwise unused. + */ + uint8_t authTimeSecretHash[SHA256_DIGEST_SIZE]; }; struct u2f_generate_resp { @@ -93,6 +109,7 @@ struct u2f_sign_req { struct u2f_sign_versioned_req { uint8_t appId[U2F_APPID_SIZE]; /* Application id */ uint8_t userSecret[U2F_P256_SIZE]; + uint8_t authTimeSecret[U2F_P256_SIZE]; uint8_t hash[U2F_P256_SIZE]; uint8_t flags; struct u2f_versioned_key_handle keyHandle; diff --git a/include/u2f_impl.h b/include/u2f_impl.h index 5bd69309c6..2c63d11d87 100644 --- a/include/u2f_impl.h +++ b/include/u2f_impl.h @@ -76,13 +76,14 @@ int u2f_origin_user_keyhandle(const uint8_t *origin, const uint8_t *user, * @param user pointer to user secret * @param seed pointer to origin-specific random seed * @param version the version byte to pack; should be greater than 0. - * @param key_handle buffer to hold the output key handle + * @param key_handle_header buffer to hold the output key handle header * * @return EC_SUCCESS if a valid keypair was created. */ int u2f_origin_user_versioned_keyhandle( const uint8_t *origin, const uint8_t *user, const uint8_t *seed, - uint8_t version, struct u2f_versioned_key_handle *key_handle); + uint8_t version, + struct u2f_versioned_key_handle_header *key_handle_header); /** * Generate an origin and user-specific ECDSA keypair from the specified @@ -101,6 +102,16 @@ int u2f_origin_user_versioned_keyhandle( int u2f_origin_user_keypair(const uint8_t *key_handle, size_t key_handle_size, p256_int *d, p256_int *pk_x, p256_int *pk_y); +/** + * Derive an hmac from the given salt, key handle and hash. The salt is to make + * sure the hmac is different for different key handles of one user. The key + * handle header is encoded into the authorization hmac to protect against + * swapping auth time secret. + */ +int u2f_authorization_hmac(const uint8_t *authorization_salt, + const struct u2f_versioned_key_handle_header *header, + const uint8_t *auth_time_secret_hash, uint8_t *hmac); + /*** * Generate a hardware derived 256b private key. * |