gpg: parse curve OID from public key to select curve name

trezor_agent/formats.py

@@ -204,4 +204,5 @@ def get_ecdh_curve_name(signature_curve_name):
     return {
         CURVE_NIST256: ECDH_NIST256,
         CURVE_ED25519: ECDH_CURVE25519,
+        ECDH_CURVE25519: ECDH_CURVE25519,
     }[signature_curve_name]

trezor_agent/gpg/decode.py

@@ -83,9 +83,15 @@ def _parse_ed25519_verifier(mpi):
     return _ed25519_verify, vk
 
 
+def _parse_curve25519_verifier(_):
+    log.warning('Curve25519 ECDH is not verified')
+    return None, None
+
+
 SUPPORTED_CURVES = {
     b'\x2A\x86\x48\xCE\x3D\x03\x01\x07': _parse_nist256p1_verifier,
     b'\x2B\x06\x01\x04\x01\xDA\x47\x0F\x01': _parse_ed25519_verifier,
+    b'\x2B\x06\x01\x04\x01\x97\x55\x01\x05\x01': _parse_curve25519_verifier,
 }
 
 RSA_ALGO_IDS = {1, 2, 3}
@@ -168,6 +174,7 @@ def _parse_pubkey(stream, packet_type='pubkey'):
             oid_size = stream.readfmt('B')
             oid = stream.read(oid_size)
             assert oid in SUPPORTED_CURVES, util.hexlify(oid)
+            p['curve_oid'] = oid
             parser = SUPPORTED_CURVES[oid]
 
             mpi = parse_mpi(stream)

trezor_agent/gpg/encode.py

@@ -3,10 +3,11 @@ import logging
 import time
 
 from . import decode, device, keyring, protocol
-from .. import formats, util
+from .. import util
 
 log = logging.getLogger(__name__)
 
+
 def _time_format(t):
     return time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(t))
 
@@ -109,10 +110,10 @@ def create_subkey(primary_bytes, pubkey, signer_func):
 
 def load_from_public_key(pubkey_dict):
     """Load correct public key from the device."""
+    log.debug('pubkey_dict: %s', pubkey_dict)
     user_id = pubkey_dict['user_id']
     created = pubkey_dict['created']
-    curve_name = protocol.find_curve_by_algo_id(pubkey_dict['algo'])
-    assert curve_name in formats.SUPPORTED_CURVES
+    curve_name = protocol.get_curve_name_by_oid(pubkey_dict['curve_oid'])
     ecdh = (pubkey_dict['algo'] == protocol.ECDH_ALGO_ID)
 
     conn = device.HardwareSigner(user_id, curve_name=curve_name)

trezor_agent/gpg/protocol.py

@@ -155,14 +155,12 @@ ECDH_ALGO_ID = 18
 CUSTOM_SUBPACKET = subpacket(100, b'TREZOR-GPG')  # marks "our" pubkey
 
 
-def find_curve_by_algo_id(algo_id):
-    """Find curve name that matches a public key algorith ID."""
-    if algo_id == ECDH_ALGO_ID:
-        return formats.CURVE_NIST256
-
-    curve_name, = [name for name, info in SUPPORTED_CURVES.items()
-                   if info['algo_id'] == algo_id]
-    return curve_name
+def get_curve_name_by_oid(oid):
+    """Return curve name matching specified OID, or raise KeyError."""
+    for curve_name, info in SUPPORTED_CURVES.items():
+        if info['oid'] == oid:
+            return curve_name
+    raise KeyError('Unknown OID: {!r}'.format(oid))
 
 
 class PublicKey(object):
@@ -173,7 +171,7 @@ class PublicKey(object):
         self.curve_info = SUPPORTED_CURVES[curve_name]
         self.created = int(created)  # time since Epoch
         self.verifying_key = verifying_key
-        self.ecdh = ecdh
+        self.ecdh = bool(ecdh)
         if ecdh:
             self.algo_id = ECDH_ALGO_ID
             self.ecdh_packet = b'\x03\x01\x08\x07'

trezor_agent/gpg/tests/test_protocol.py

@@ -30,11 +30,6 @@ def test_mpi():
     assert protocol.mpi(0x123) == b'\x00\x09\x01\x23'
 
 
-def test_find():
-    assert protocol.find_curve_by_algo_id(19) == formats.CURVE_NIST256
-    assert protocol.find_curve_by_algo_id(22) == formats.CURVE_ED25519
-
-
 def test_armor():
     data = bytearray(range(256))
     assert protocol.armor(data, 'TEST') == '''-----BEGIN PGP TEST-----