def test_set_curve_in_key():
with pytest.raises(CoseException) as excinfo:
key = EC2Key(crv='P257', d=os.urandom(32))
assert "Unknown COSE header or key attribute" in str(excinfo)
with pytest.raises(CoseException) as excinfo:
key = EC2Key(crv='Ed25519', d=os.urandom(32))
assert "Unknown COSE header or key attribute" in str(excinfo)
key = EC2Key(crv='P_256', d=os.urandom(32))
assert key.crv == P256
def test_set_curve_in_key():
with pytest.raises(CoseException) as excinfo:
_ = EC2Key(crv='P257', d=p256_d)
assert "Unknown COSE attribute with value: [CoseCurve - P257]" in str(
excinfo)
with pytest.raises(CoseUnsupportedCurve) as excinfo:
_ = EC2Key(crv='Ed25519', d=p256_d)
assert "Invalid COSE curve <class 'cose.keys.curves.Ed25519'> for key type EC2Key" in str(
excinfo)
key = EC2Key(crv='P_256', d=p256_d)
assert key.crv == P256
def test_unknown_key_attribute():
key = EC2Key(crv='P_256',
d=p256_d,
optional_params={"subject_name": "signing key"})
assert "subject_name" in key
assert key['subject_name'] == "signing key"
def test_fail_on_illegal_kty(crv, kty):
params = {KpKty: kty}
with pytest.raises(CoseIllegalKeyType) as excinfo:
_ = EC2Key(crv=crv, x=os.urandom(32), y=os.urandom(32), d=os.urandom(32), optional_params=params)
assert "Illegal key type in EC2 COSE Key" in str(excinfo.value)
def setup_dh_key(selected_cipher: int, private_bytes: bytes):
if CipherSuite.from_id(selected_cipher).dh_curve in [X448, X25519]:
return OKPKey(d=private_bytes, crv=CipherSuite.from_id(selected_cipher).dh_curve)
elif CipherSuite.from_id(selected_cipher).dh_curve in [P256]:
return EC2Key(d=private_bytes, crv=CipherSuite.from_id(selected_cipher).sign_curve)
else:
raise ValueError("Illegal DH keys.")
def remote_pubkey(self) -> RPK:
""" Returns the remote ephemeral public key. """
if self.cipher_suite.dh_curve in [X448, X25519]:
return OKPKey(x=self.g_y, crv=self.cipher_suite.dh_curve)
else:
return EC2Key(x=self.g_y, crv=self.cipher_suite.dh_curve)
def local_pubkey(self) -> RPK:
""" Returns the local ephemeral public key. """
# Is this a good criterion? (Possibly there doesn't need to be a
# distinction; self.cipher_suite.dh_curve.keyclass(...) could do)
if self.cipher_suite.dh_curve in [X448, X25519]:
return OKPKey(x=self.g_y, crv=self.cipher_suite.dh_curve)
else:
return EC2Key(x=self.g_y, crv=self.cipher_suite.dh_curve)
def setup_sign_key(selected_cipher: int, private_bytes: bytes):
if CipherSuite.from_id(selected_cipher).sign_curve in [Ed448, Ed25519]:
return OKPKey(d=private_bytes,
crv=CipherSuite.from_id(selected_cipher).sign_curve,
optional_params={KpAlg: CipherSuite.from_id(selected_cipher).sign_alg})
elif CipherSuite.from_id(selected_cipher).sign_alg == Es256:
return EC2Key(d=private_bytes, alg=Es256, crv=CipherSuite.from_id(selected_cipher).sign_curve)
else:
raise ValueError("Illegal COSE curve.")
def test_fail_on_illegal_kty(crv, kty):
params = {KpKty: kty}
# NOTE: the stuff in params will override the parameters of the function if they are specified twice
# Here the KpKty value which is set by the constructor gets overwritten by the params dict
with pytest.raises(CoseIllegalKeyType) as excinfo:
_ = EC2Key(crv=crv,
x=p256_x,
y=p256_y,
d=p256_d,
optional_params=params)
assert "Illegal key type in EC2 COSE Key" in str(excinfo.value)
def create_cose_1_sign_msg(payload, private_key):
crv = P384
d_value = private_key.private_numbers().private_value
x_coor = private_key.public_key().public_numbers().x
y_coor = private_key.public_key().public_numbers().y
key = EC2Key(
crv=crv,
d=d_value.to_bytes(crv.size, "big"),
x=x_coor.to_bytes(crv.size, "big"),
y=y_coor.to_bytes(crv.size, "big"),
)
phdr = {1: Es384}
msg = Sign1Message(phdr=phdr, payload=payload, key=key)
sig = msg.compute_signature()
msg._signature = sig
return msg.encode(tag=False)
def verify_attestation_signature(payload, cert):
logger.debug("* Verifying attestation certificate signature...")
cert = load_der_x509_certificate(cert)
cert_public_numbers = cert.public_key().public_numbers()
x = cert_public_numbers.x
y = cert_public_numbers.y
x = _long_to_bytes(x)
y = _long_to_bytes(y)
# Create the EC2 key from public key parameters
key = EC2Key(x=x, y=y, crv=P384)
cose_obj = cbor2.loads(payload)
msg = Sign1Message.from_cose_obj(cose_obj, allow_unknown_attributes=True)
msg.key = key
# Verify the signature using the EC2 key
verified = msg.verify_signature()
if not verified:
errmsg = "Malformed attestation doc: incorrect certificate signature."
logger.error(errmsg)
raise RuntimeError(errmsg)
logger.debug("* Attestation certificate signature verified.")
def test_on_missing_public_y_values(crv, x):
key = EC2Key(crv=crv, x=x)
assert key.y
def test_fail_with_d_and_missing_public_y_values(crv):
with pytest.raises(CoseInvalidKey) as excinfo:
_ = EC2Key(crv=crv, x=os.urandom(32), d=os.urandom(32))
assert "Missing public coordinate X/Y" in str(excinfo.value)
def test(self):
print('\nTest: ' + __name__ + '.' + type(self).__name__)
private_key = EC2Key(
crv=curves.P256,
x=binascii.unhexlify('44c1fa63b84f172b50541339c50beb0e630241ecb4eebbddb8b5e4fe0a1787a8'),
y=binascii.unhexlify('059451c7630d95d0b550acbd02e979b3f4f74e645b74715fafbc1639960a0c7a'),
d=binascii.unhexlify('dd6e7d8c4c0e0c0bd3ae1b4a2fa86b9a09b7efee4a233772cf5189786ea63842'),
optional_params={
keyparam.KpKid: b'ExampleEC2',
keyparam.KpKeyOps: [keyops.SignOp, keyops.VerifyOp],
}
)
print('Private Key: {}'.format(encode_diagnostic(cbor2.loads(private_key.encode()))))
# Primary block
prim_dec = self._get_primary_item()
prim_enc = cbor2.dumps(prim_dec)
print('Primary Block: {}'.format(encode_diagnostic(prim_dec)))
print('Encoded: {}'.format(encode_diagnostic(prim_enc)))
# Security target block
target_dec = self._get_target_item()
target_enc = cbor2.dumps(target_dec)
content_plaintext = target_dec[4]
print('Target Block: {}'.format(encode_diagnostic(target_dec)))
print('Plaintext: {}'.format(encode_diagnostic(content_plaintext)))
# Combined AAD
ext_aad_dec = self._get_aad_item()
ext_aad_enc = cbor2.dumps(ext_aad_dec)
print('External AAD: {}'.format(encode_diagnostic(ext_aad_dec)))
print('Encoded: {}'.format(encode_diagnostic(ext_aad_enc)))
msg_obj = Sign1Message(
phdr={
headers.Algorithm: algorithms.Es256,
},
uhdr={
headers.KID: private_key.kid,
},
payload=content_plaintext,
# Non-encoded parameters
external_aad=ext_aad_enc,
)
msg_obj.key = private_key
# COSE internal structure
cose_struct_enc = msg_obj._sig_structure
cose_struct_dec = cbor2.loads(cose_struct_enc)
print('COSE Structure: {}'.format(encode_diagnostic(cose_struct_dec)))
print('Encoded: {}'.format(encode_diagnostic(cose_struct_enc)))
# Encoded message
message_enc = msg_obj.encode(tag=False)
message_dec = cbor2.loads(message_enc)
# Detach the payload
content_signature = message_dec[2]
message_dec[2] = None
self._print_message(message_dec, recipient_idx=4)
message_enc = cbor2.dumps(message_dec)
# ASB structure
asb_dec = self._get_asb_item([
msg_obj.cbor_tag,
message_enc
])
asb_enc = self._get_asb_enc(asb_dec)
print('ASB: {}'.format(encode_diagnostic(asb_dec)))
print('Encoded: {}'.format(encode_diagnostic(asb_enc)))
bpsec_dec = self._get_bpsec_item(
block_type=BlockType.BIB,
asb_dec=asb_dec,
)
bpsec_enc = cbor2.dumps(bpsec_dec)
print('BPSec block: {}'.format(encode_diagnostic(bpsec_dec)))
print('Encoded: {}'.format(encode_diagnostic(bpsec_enc)))
# Change from detached payload
message_dec[2] = content_signature
decode_obj = Sign1Message.from_cose_obj(message_dec)
decode_obj.external_aad = ext_aad_enc
decode_obj.key = private_key
verify_valid = decode_obj.verify_signature()
self.assertTrue(verify_valid)
print('Loopback verify:', verify_valid)
bundle = self._assemble_bundle([prim_enc, bpsec_enc, target_enc])
print('Total bundle: {}'.format(encode_diagnostic(bundle)))
def extract_cose_key(keyobj):
''' Get a COSE version of the local private key.
:param keyobj: The cryptography key object.
:return: The associated COSE key.
:rtype: :py:cls:`CoseKey`
'''
if isinstance(keyobj, (rsa.RSAPrivateKey, rsa.RSAPublicKey)):
if hasattr(keyobj, 'private_numbers'):
priv_nums = keyobj.private_numbers()
pub_nums = keyobj.public_key().public_numbers()
else:
priv_nums = None
pub_nums = keyobj.public_numbers()
kwargs = dict()
if pub_nums:
def convert(name, attr=None):
val = getattr(pub_nums, attr or name)
kwargs[name] = val.to_bytes((val.bit_length() + 7) // 8,
byteorder="big")
convert('n')
convert('e')
if priv_nums:
def convert(name, attr=None):
val = getattr(priv_nums, attr or name)
kwargs[name] = val.to_bytes((val.bit_length() + 7) // 8,
byteorder="big")
convert('d')
convert('p')
convert('q')
convert('dp', 'dmp1')
convert('dq', 'dmq1')
convert('qinv', 'iqmp')
cose_key = RSAKey(**kwargs)
cose_key.alg = algorithms.Ps256
elif isinstance(
keyobj,
(ec.EllipticCurvePrivateKey, ec.EllipticCurvePublicKey)):
CURVE_CLS_MAP = {
ec.SECP256R1: curves.P256,
ec.SECP384R1: curves.P384,
ec.SECP521R1: curves.P521,
}
CURVE_ALG_MAP = {
ec.SECP256R1: algorithms.Es256,
ec.SECP384R1: algorithms.Es384,
ec.SECP521R1: algorithms.Es512,
}
try:
curve_cls = CURVE_CLS_MAP[type(keyobj.curve)]
except KeyError:
raise CoseUnsupportedCurve('Cannot match curve for {}'.format(
repr(keyobj)))
LOGGER.debug('Found COSE curve %s', curve_cls)
try:
alg_cls = CURVE_ALG_MAP[type(keyobj.curve)]
except KeyError:
raise CoseUnsupportedCurve(
'Cannot match algorithm for {}'.format(repr(keyobj)))
LOGGER.debug('Found COSE algorithm %s', alg_cls)
if hasattr(keyobj, 'private_numbers'):
priv_nums = keyobj.private_numbers()
pub_nums = keyobj.public_key().public_numbers()
else:
priv_nums = None
pub_nums = keyobj.public_numbers()
kwargs = dict(
crv=curve_cls,
optional_params={
keyparam.KpAlg: alg_cls,
},
)
if pub_nums:
x_coor = pub_nums.x
y_coor = pub_nums.y
kwargs.update(
dict(x=x_coor.to_bytes((x_coor.bit_length() + 7) // 8,
byteorder="big"),
y=y_coor.to_bytes((y_coor.bit_length() + 7) // 8,
byteorder="big")))
if priv_nums:
d_value = priv_nums.private_value
kwargs.update(
dict(d=d_value.to_bytes((d_value.bit_length() + 7) // 8,
byteorder="big"), ))
cose_key = EC2Key(**kwargs)
else:
raise TypeError('Cannot handle key {}'.format(repr(keyobj)))
return cose_key
def test(self):
print('\nTest: ' + __name__ + '.' + type(self).__name__)
private_key = EC2Key(
crv=curves.P256,
x=binascii.unhexlify(
'44c1fa63b84f172b50541339c50beb0e630241ecb4eebbddb8b5e4fe0a1787a8'
),
y=binascii.unhexlify(
'059451c7630d95d0b550acbd02e979b3f4f74e645b74715fafbc1639960a0c7a'
),
d=binascii.unhexlify(
'dd6e7d8c4c0e0c0bd3ae1b4a2fa86b9a09b7efee4a233772cf5189786ea63842'
),
optional_params={
keyparam.KpKid: b'ExampleEC2',
keyparam.KpKeyOps: [keyops.DeriveKeyOp],
})
print('Private Key: {}'.format(
encode_diagnostic(cbor2.loads(private_key.encode()))))
# 256-bit content encryption key
cek = SymmetricKey(k=binascii.unhexlify(
'13BF9CEAD057C0ACA2C9E52471CA4B19DDFAF4C0784E3F3E8E3999DBAE4CE45C'
),
optional_params={
keyparam.KpKid:
b'ExampleCEK',
keyparam.KpKeyOps:
[keyops.EncryptOp, keyops.DecryptOp],
})
print('CEK: {}'.format(encode_diagnostic(cbor2.loads(cek.encode()))))
# session IV
iv = binascii.unhexlify('6F3093EBA5D85143C3DC484A')
print('IV: {}'.format(binascii.hexlify(iv)))
# Would be random ephemeral key, but test constant
sender_key = EC2Key(
crv=curves.P256,
x=binascii.unhexlify(
'fedaba748882050d1bef8ba992911898f554450952070aeb4788ca57d1df6bcc'
),
y=binascii.unhexlify(
'ceaa8e7ff4751a4f81c70e98f1713378b0bd82a1414a2f493c1c9c0670f28d62'
),
d=binascii.unhexlify(
'a2e4ed4f2e21842999b0e9ebdaad7465efd5c29bd5761f5c20880f9d9c3b122a'
),
)
print('Sender Private Key: {}'.format(
encode_diagnostic(cbor2.loads(sender_key.encode()))))
sender_public = EC2Key(crv=sender_key.crv,
x=sender_key.x,
y=sender_key.y)
# Primary block
prim_dec = self._get_primary_item()
prim_enc = cbor2.dumps(prim_dec)
print('Primary Block: {}'.format(encode_diagnostic(prim_dec)))
print('Encoded: {}'.format(encode_diagnostic(prim_enc)))
# Security target block
target_dec = self._get_target_item()
content_plaintext = target_dec[4]
print('Target Block: {}'.format(encode_diagnostic(target_dec)))
print('Plaintext: {}'.format(encode_diagnostic(content_plaintext)))
# Combined AAD
ext_aad_dec = self._get_aad_item()
ext_aad_enc = cbor2.dumps(ext_aad_dec)
print('External AAD: {}'.format(encode_diagnostic(ext_aad_dec)))
print('Encoded: {}'.format(encode_diagnostic(ext_aad_enc)))
msg_obj = EncMessage(
phdr={
headers.Algorithm: algorithms.A256GCM,
},
uhdr={
headers.IV: iv,
},
payload=content_plaintext,
recipients=[
KeyAgreementWithKeyWrap(
uhdr={
headers.Algorithm: algorithms.EcdhEsA256KW,
headers.KID: private_key.kid,
headers.EphemeralKey: sender_public,
},
payload=cek.k,
),
],
# Non-encoded parameters
external_aad=ext_aad_enc,
)
recip = msg_obj.recipients[0]
recip.key = sender_key
recip.local_attrs = {
headers.StaticKey: private_key,
}
# COSE internal structure
cose_struct_enc = msg_obj._enc_structure
cose_struct_dec = cbor2.loads(cose_struct_enc)
print('COSE Structure: {}'.format(encode_diagnostic(cose_struct_dec)))
print('Encoded: {}'.format(encode_diagnostic(cose_struct_enc)))
# Encoded message
message_enc = msg_obj.encode(tag=False)
message_dec = cbor2.loads(message_enc)
# Detach the payload
content_ciphertext = message_dec[2]
message_dec[2] = None
self._print_message(message_dec, recipient_idx=3)
print('Ciphertext: {}'.format(encode_diagnostic(content_ciphertext)))
message_enc = cbor2.dumps(message_dec)
# ASB structure
asb_dec = self._get_asb_item([msg_obj.cbor_tag, message_enc])
asb_enc = self._get_asb_enc(asb_dec)
print('ASB: {}'.format(encode_diagnostic(asb_dec)))
print('Encoded: {}'.format(encode_diagnostic(asb_enc)))
bpsec_dec = self._get_bpsec_item(
block_type=BlockType.BCB,
asb_dec=asb_dec,
)
bpsec_enc = cbor2.dumps(bpsec_dec)
print('BPSec block: {}'.format(encode_diagnostic(bpsec_dec)))
print('Encoded: {}'.format(encode_diagnostic(bpsec_enc)))
# Change from detached payload
message_dec[2] = content_ciphertext
decode_obj = EncMessage.from_cose_obj(message_dec)
decode_obj.external_aad = ext_aad_enc
recip = decode_obj.recipients[0]
recip.key = private_key
decode_plaintext = decode_obj.decrypt(recipient=recip)
print('Loopback plaintext:', encode_diagnostic(decode_plaintext))
self.assertEqual(content_plaintext, decode_plaintext)
print('Loopback CEK:',
encode_diagnostic(cbor2.loads(decode_obj.key.encode())))
self.assertEqual(cek.k, decode_obj.key.k)
target_dec[4] = content_ciphertext
target_enc = cbor2.dumps(target_dec)
bundle = self._assemble_bundle([prim_enc, bpsec_enc, target_enc])
print('Total bundle: {}'.format(encode_diagnostic(bundle)))
def test_ec2_key_construction(crv):
key = EC2Key(crv=crv, x=os.urandom(32), y=os.urandom(32), d=os.urandom(32))
assert _is_valid_ec2_key(key)
def test_ec2_key_construction(crv, x, y, d):
key = EC2Key(crv=crv, x=x, y=y, d=d)
assert _is_valid_ec2_key(key)
def test_fail_with_d_and_missing_public_y_values(crv, x, d):
key = EC2Key(crv=crv, x=x, d=d)
assert key.y
def test_with_d_and_missing_public_x_values(crv, y, d):
key = EC2Key(crv=crv, y=y, d=d)
assert key.x
def test_fail_on_missing_key_values(crv):
with pytest.raises(CoseInvalidKey) as excinfo:
_ = EC2Key(crv=crv)
assert "Either the public values or the private value must be specified" in str(
excinfo.value)
def test_fail_on_missing_public_x_values(crv, y):
with pytest.raises(CoseInvalidKey) as excinfo:
_ = EC2Key(crv=crv, y=y)
assert "Missing public coordinate X" in str(excinfo.value)
