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new CoseKey data format

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This commit is contained in:
Fabian Kaczmarczyck
2021-01-12 15:11:20 +01:00
parent 688d11c6b6
commit 2776bd9b8e
6 changed files with 196 additions and 99 deletions
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13
src/ctap/command.rs
View File

@@ -317,7 +317,7 @@ impl TryFrom<cbor::Value> for AuthenticatorClientPinParameters {
let pin_protocol = extract_unsigned(ok_or_missing(pin_protocol)?)?;
let sub_command = ClientPinSubCommand::try_from(ok_or_missing(sub_command)?)?;
let key_agreement = key_agreement.map(extract_map).transpose()?.map(CoseKey);
let key_agreement = key_agreement.map(CoseKey::try_from).transpose()?;
let pin_auth = pin_auth.map(extract_byte_string).transpose()?;
let new_pin_enc = new_pin_enc.map(extract_byte_string).transpose()?;
let pin_hash_enc = pin_hash_enc.map(extract_byte_string).transpose()?;
@@ -423,8 +423,8 @@ mod test {
};
use super::super::ES256_CRED_PARAM;
use super::*;
use alloc::collections::BTreeMap;
use cbor::{cbor_array, cbor_map};
use crypto::rng256::ThreadRng256;
#[test]
fn test_from_cbor_make_credential_parameters() {
@@ -534,10 +534,15 @@ mod test {
#[test]
fn test_from_cbor_client_pin_parameters() {
let mut rng = ThreadRng256 {};
let sk = crypto::ecdh::SecKey::gensk(&mut rng);
let pk = sk.genpk();
let cose_key = CoseKey::from(pk);
let cbor_value = cbor_map! {
1 => 1,
2 => ClientPinSubCommand::GetPinRetries,
3 => cbor_map!{},
3 => cbor::Value::from(cose_key.clone()),
4 => vec! [0xBB],
5 => vec! [0xCC],
6 => vec! [0xDD],
@@ -552,7 +557,7 @@ mod test {
let expected_pin_protocol_parameters = AuthenticatorClientPinParameters {
pin_protocol: 1,
sub_command: ClientPinSubCommand::GetPinRetries,
key_agreement: Some(CoseKey(BTreeMap::new())),
key_agreement: Some(cose_key),
pin_auth: Some(vec![0xBB]),
new_pin_enc: Some(vec![0xCC]),
pin_hash_enc: Some(vec![0xDD]),

275
src/ctap/data_formats.rs
View File

@@ -17,12 +17,23 @@ use alloc::collections::BTreeMap;
use alloc::string::String;
use alloc::vec::Vec;
use arrayref::array_ref;
use cbor::{cbor_array_vec, cbor_bytes_lit, cbor_map_options, destructure_cbor_map};
use core::convert::{TryFrom, TryInto};
use cbor::{cbor_array_vec, cbor_map, cbor_map_options, destructure_cbor_map};
use core::convert::TryFrom;
use crypto::{ecdh, ecdsa};
#[cfg(test)]
use enum_iterator::IntoEnumIterator;
// This is the algorithm specifier that is supposed to be used in a COSE key
// map in ECDH. CTAP requests -25 which represents ECDH-ES + HKDF-256 here:
// https://www.iana.org/assignments/cose/cose.xhtml#algorithms
const ECDH_ALGORITHM: i64 = -25;
// This is the identifier used for ECDSA and ECDH in OpenSSH.
const ES256_ALGORITHM: i64 = -7;
// The COSE key parameter behind map key 1.
const EC2_KEY_TYPE: i64 = 2;
// The COSE key parameter behind map key -1.
const P_256_CURVE: i64 = 1;
// https://www.w3.org/TR/webauthn/#dictdef-publickeycredentialrpentity
#[cfg_attr(any(test, feature = "debug_ctap"), derive(Debug, PartialEq))]
pub struct PublicKeyCredentialRpEntity {
@@ -322,17 +333,17 @@ impl TryFrom<cbor::Value> for GetAssertionHmacSecretInput {
fn try_from(cbor_value: cbor::Value) -> Result<Self, Ctap2StatusCode> {
destructure_cbor_map! {
let {
1 => cose_key,
1 => key_agreement,
2 => salt_enc,
3 => salt_auth,
} = extract_map(cbor_value)?;
}
let cose_key = extract_map(ok_or_missing(cose_key)?)?;
let key_agreement = CoseKey::try_from(ok_or_missing(key_agreement)?)?;
let salt_enc = extract_byte_string(ok_or_missing(salt_enc)?)?;
let salt_auth = extract_byte_string(ok_or_missing(salt_auth)?)?;
Ok(Self {
key_agreement: CoseKey(cose_key),
key_agreement,
salt_enc,
salt_auth,
})
@@ -432,7 +443,7 @@ impl From<PackedAttestationStatement> for cbor::Value {
#[derive(PartialEq)]
#[cfg_attr(any(test, feature = "debug_ctap"), derive(Debug))]
pub enum SignatureAlgorithm {
ES256 = ecdsa::PubKey::ES256_ALGORITHM as isize,
ES256 = ES256_ALGORITHM as isize,
// This is the default for all numbers not covered above.
// Unknown types should be ignored, instead of returning errors.
Unknown = 0,
@@ -449,7 +460,7 @@ impl TryFrom<cbor::Value> for SignatureAlgorithm {
fn try_from(cbor_value: cbor::Value) -> Result<Self, Ctap2StatusCode> {
match extract_integer(cbor_value)? {
ecdsa::PubKey::ES256_ALGORITHM => Ok(SignatureAlgorithm::ES256),
ES256_ALGORITHM => Ok(SignatureAlgorithm::ES256),
_ => Ok(SignatureAlgorithm::Unknown),
}
}
@@ -614,85 +625,31 @@ impl PublicKeyCredentialSource {
}
}
// TODO(kaczmarczyck) we could decide to split this data type up
// It depends on the algorithm though, I think.
// So before creating a mess, this is my workaround.
// The COSE key is used for both ECDH and ECDSA public keys for transmission.
#[derive(Clone)]
#[cfg_attr(any(test, feature = "debug_ctap"), derive(Debug, PartialEq))]
pub struct CoseKey(pub BTreeMap<cbor::KeyType, cbor::Value>);
// This is the algorithm specifier that is supposed to be used in a COSE key
// map. The CTAP specification says -25 which represents ECDH-ES + HKDF-256
// here: https://www.iana.org/assignments/cose/cose.xhtml#algorithms
// In fact, this is just used for compatibility with older specification versions.
const ECDH_ALGORITHM: i64 = -25;
// This is the identifier used by OpenSSH. To be compatible, we accept both.
const ES256_ALGORITHM: i64 = -7;
const EC2_KEY_TYPE: i64 = 2;
const P_256_CURVE: i64 = 1;
pub struct CoseKey {
x_bytes: [u8; ecdh::NBYTES],
y_bytes: [u8; ecdh::NBYTES],
algorithm: i64,
}
// This conversion accepts both ECDH and ECDSA.
impl TryFrom<cbor::Value> for CoseKey {
type Error = Ctap2StatusCode;
fn try_from(cbor_value: cbor::Value) -> Result<Self, Ctap2StatusCode> {
if let cbor::Value::Map(cose_map) = cbor_value {
Ok(CoseKey(cose_map))
} else {
Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR)
}
}
}
fn cose_key_from_bytes(x_bytes: [u8; ecdh::NBYTES], y_bytes: [u8; ecdh::NBYTES]) -> CoseKey {
let x_byte_cbor: cbor::Value = cbor_bytes_lit!(&x_bytes);
let y_byte_cbor: cbor::Value = cbor_bytes_lit!(&y_bytes);
// TODO(kaczmarczyck) do not write optional parameters, spec is unclear
let cose_cbor_value = cbor_map_options! {
1 => EC2_KEY_TYPE,
3 => ECDH_ALGORITHM,
-1 => P_256_CURVE,
-2 => x_byte_cbor,
-3 => y_byte_cbor,
};
// Unwrap is safe here since we know it's a map.
cose_cbor_value.try_into().unwrap()
}
impl From<ecdh::PubKey> for CoseKey {
fn from(pk: ecdh::PubKey) -> Self {
let mut x_bytes = [0; ecdh::NBYTES];
let mut y_bytes = [0; ecdh::NBYTES];
pk.to_coordinates(&mut x_bytes, &mut y_bytes);
cose_key_from_bytes(x_bytes, y_bytes)
}
}
impl TryFrom<CoseKey> for ecdh::PubKey {
type Error = Ctap2StatusCode;
fn try_from(cose_key: CoseKey) -> Result<Self, Ctap2StatusCode> {
destructure_cbor_map! {
let {
// This is sorted correctly, negative encoding is bigger.
1 => key_type,
3 => algorithm,
-1 => curve,
-2 => x_bytes,
-3 => y_bytes,
} = cose_key.0;
} = extract_map(cbor_value)?;
}
let key_type = extract_integer(ok_or_missing(key_type)?)?;
if key_type != EC2_KEY_TYPE {
return Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM);
}
let algorithm = extract_integer(ok_or_missing(algorithm)?)?;
if algorithm != ECDH_ALGORITHM && algorithm != ES256_ALGORITHM {
return Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM);
}
let curve = extract_integer(ok_or_missing(curve)?)?;
if curve != P_256_CURVE {
return Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM);
}
let x_bytes = extract_byte_string(ok_or_missing(x_bytes)?)?;
if x_bytes.len() != ecdh::NBYTES {
return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
@@ -701,11 +658,55 @@ impl TryFrom<CoseKey> for ecdh::PubKey {
if y_bytes.len() != ecdh::NBYTES {
return Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER);
}
let curve = extract_integer(ok_or_missing(curve)?)?;
if curve != P_256_CURVE {
return Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM);
}
let key_type = extract_integer(ok_or_missing(key_type)?)?;
if key_type != EC2_KEY_TYPE {
return Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM);
}
let algorithm = extract_integer(ok_or_missing(algorithm)?)?;
if algorithm != ECDH_ALGORITHM && algorithm != ES256_ALGORITHM {
return Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM);
}
let x_array_ref = array_ref![x_bytes.as_slice(), 0, ecdh::NBYTES];
let y_array_ref = array_ref![y_bytes.as_slice(), 0, ecdh::NBYTES];
ecdh::PubKey::from_coordinates(x_array_ref, y_array_ref)
.ok_or(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
Ok(CoseKey {
x_bytes: *array_ref![x_bytes.as_slice(), 0, ecdh::NBYTES],
y_bytes: *array_ref![y_bytes.as_slice(), 0, ecdh::NBYTES],
algorithm,
})
}
}
impl From<CoseKey> for cbor::Value {
fn from(cose_key: CoseKey) -> Self {
let CoseKey {
x_bytes,
y_bytes,
algorithm,
} = cose_key;
cbor_map! {
1 => EC2_KEY_TYPE,
3 => algorithm,
-1 => P_256_CURVE,
-2 => x_bytes,
-3 => y_bytes,
}
}
}
impl From<ecdh::PubKey> for CoseKey {
fn from(pk: ecdh::PubKey) -> Self {
let mut x_bytes = [0; ecdh::NBYTES];
let mut y_bytes = [0; ecdh::NBYTES];
pk.to_coordinates(&mut x_bytes, &mut y_bytes);
CoseKey {
x_bytes,
y_bytes,
algorithm: ECDH_ALGORITHM,
}
}
}
@@ -714,7 +715,32 @@ impl From<ecdsa::PubKey> for CoseKey {
let mut x_bytes = [0; ecdh::NBYTES];
let mut y_bytes = [0; ecdh::NBYTES];
pk.to_coordinates(&mut x_bytes, &mut y_bytes);
cose_key_from_bytes(x_bytes, y_bytes)
CoseKey {
x_bytes,
y_bytes,
algorithm: ES256_ALGORITHM,
}
}
}
impl TryFrom<CoseKey> for ecdh::PubKey {
type Error = Ctap2StatusCode;
fn try_from(cose_key: CoseKey) -> Result<Self, Ctap2StatusCode> {
let CoseKey {
x_bytes,
y_bytes,
algorithm,
} = cose_key;
// Since algorithm can be used for different COSE key types, we check
// whether the current type is correct for ECDH. For an OpenSSH bugfix,
// the algorithm ES256_ALGORITHM is allowed here too.
if algorithm != ECDH_ALGORITHM && algorithm != ES256_ALGORITHM {
return Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM);
}
ecdh::PubKey::from_coordinates(&x_bytes, &y_bytes)
.ok_or(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
}
}
@@ -827,8 +853,8 @@ mod test {
use super::*;
use alloc::collections::BTreeMap;
use cbor::{
cbor_array, cbor_bool, cbor_bytes, cbor_false, cbor_int, cbor_map, cbor_null, cbor_text,
cbor_unsigned,
cbor_array, cbor_bool, cbor_bytes, cbor_bytes_lit, cbor_false, cbor_int, cbor_null,
cbor_text, cbor_unsigned,
};
use crypto::rng256::{Rng256, ThreadRng256};
@@ -1151,7 +1177,7 @@ mod test {
#[test]
fn test_from_into_signature_algorithm() {
let cbor_signature_algorithm: cbor::Value = cbor_int!(ecdsa::PubKey::ES256_ALGORITHM);
let cbor_signature_algorithm: cbor::Value = cbor_int!(ES256_ALGORITHM);
let signature_algorithm = SignatureAlgorithm::try_from(cbor_signature_algorithm.clone());
let expected_signature_algorithm = SignatureAlgorithm::ES256;
assert_eq!(signature_algorithm, Ok(expected_signature_algorithm));
@@ -1225,7 +1251,7 @@ mod test {
fn test_from_into_public_key_credential_parameter() {
let cbor_credential_parameter = cbor_map! {
"type" => "public-key",
"alg" => ecdsa::PubKey::ES256_ALGORITHM,
"alg" => ES256_ALGORITHM,
};
let credential_parameter =
PublicKeyCredentialParameter::try_from(cbor_credential_parameter.clone());
@@ -1279,7 +1305,7 @@ mod test {
let cose_key = CoseKey::from(pk);
let cbor_extensions = cbor_map! {
"hmac-secret" => cbor_map! {
1 => cbor::Value::Map(cose_key.0.clone()),
1 => cbor::Value::from(cose_key.clone()),
2 => vec![0x02; 32],
3 => vec![0x03; 16],
},
@@ -1343,6 +1369,83 @@ mod test {
assert_eq!(created_cbor, cbor_packed_attestation_statement);
}
#[test]
fn test_from_into_cose_key_cbor() {
for algorithm in &[ECDH_ALGORITHM, ES256_ALGORITHM] {
let cbor_value = cbor_map! {
1 => EC2_KEY_TYPE,
3 => algorithm,
-1 => P_256_CURVE,
-2 => [0u8; 32],
-3 => [0u8; 32],
};
let cose_key = CoseKey::try_from(cbor_value.clone()).unwrap();
let created_cbor_value = cbor::Value::from(cose_key);
assert_eq!(created_cbor_value, cbor_value);
}
let cbor_value = cbor_map! {
1 => EC2_KEY_TYPE,
// unknown algorithm
3 => 0,
-1 => P_256_CURVE,
-2 => [0u8; 32],
-3 => [0u8; 32],
};
assert_eq!(
CoseKey::try_from(cbor_value),
Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM)
);
let cbor_value = cbor_map! {
// unknown type
1 => 0,
3 => ECDH_ALGORITHM,
-1 => P_256_CURVE,
-2 => [0u8; 32],
-3 => [0u8; 32],
};
assert_eq!(
CoseKey::try_from(cbor_value),
Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM)
);
let cbor_value = cbor_map! {
1 => EC2_KEY_TYPE,
3 => ECDH_ALGORITHM,
// unknown curve
-1 => 0,
-2 => [0u8; 32],
-3 => [0u8; 32],
};
assert_eq!(
CoseKey::try_from(cbor_value),
Err(Ctap2StatusCode::CTAP2_ERR_UNSUPPORTED_ALGORITHM)
);
let cbor_value = cbor_map! {
1 => EC2_KEY_TYPE,
3 => ECDH_ALGORITHM,
-1 => P_256_CURVE,
// wrong length
-2 => [0u8; 31],
-3 => [0u8; 32],
};
assert_eq!(
CoseKey::try_from(cbor_value),
Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
);
let cbor_value = cbor_map! {
1 => EC2_KEY_TYPE,
3 => ECDH_ALGORITHM,
-1 => P_256_CURVE,
-2 => [0u8; 32],
// wrong length
-3 => [0u8; 33],
};
assert_eq!(
CoseKey::try_from(cbor_value),
Err(Ctap2StatusCode::CTAP1_ERR_INVALID_PARAMETER)
);
}
#[test]
fn test_from_into_cose_key_ecdh() {
let mut rng = ThreadRng256 {};
@@ -1359,17 +1462,7 @@ mod test {
let sk = crypto::ecdsa::SecKey::gensk(&mut rng);
let pk = sk.genpk();
let cose_key = CoseKey::from(pk);
let cose_map = cose_key.0;
let template = cbor_map! {
1 => 0,
3 => 0,
-1 => 0,
-2 => 0,
-3 => 0,
};
for key in CoseKey::try_from(template).unwrap().0.keys() {
assert!(cose_map.contains_key(key));
}
assert_eq!(cose_key.algorithm, ES256_ALGORITHM);
}
#[test]

2
src/ctap/mod.rs
View File

@@ -534,7 +534,7 @@ where
}
auth_data.extend(vec![0x00, credential_id.len() as u8]);
auth_data.extend(&credential_id);
if !cbor::write(cbor::Value::Map(CoseKey::from(pk).0), &mut auth_data) {
if !cbor::write(cbor::Value::from(CoseKey::from(pk)), &mut auth_data) {
return Err(Ctap2StatusCode::CTAP2_ERR_VENDOR_INTERNAL_ERROR);
}
if has_extension_output {

2
src/ctap/response.rs
View File

@@ -192,7 +192,7 @@ impl From<AuthenticatorClientPinResponse> for cbor::Value {
} = client_pin_response;
cbor_map_options! {
1 => key_agreement.map(|cose_key| cbor_map_btree!(cose_key.0)),
1 => key_agreement.map(cbor::Value::from),
2 => pin_token,
3 => retries,
}