Split the package into a shared library and separate per-device packages

libagent/gpg/encode.py

@@ -0,0 +1,103 @@
+"""Create GPG ECDSA signatures and public keys using TREZOR device."""
+import io
+import logging
+
+from . import decode, keyring, protocol
+from .. import util
+
+log = logging.getLogger(__name__)
+
+
+def create_primary(user_id, pubkey, signer_func, secret_bytes=b''):
+    """Export new primary GPG public key, ready for "gpg2 --import"."""
+    pubkey_packet = protocol.packet(tag=(5 if secret_bytes else 6),
+                                    blob=(pubkey.data() + secret_bytes))
+    user_id_packet = protocol.packet(tag=13,
+                                     blob=user_id.encode('ascii'))
+
+    data_to_sign = (pubkey.data_to_hash() +
+                    user_id_packet[:1] +
+                    util.prefix_len('>L', user_id.encode('ascii')))
+    hashed_subpackets = [
+        protocol.subpacket_time(pubkey.created),  # signature time
+        # https://tools.ietf.org/html/rfc4880#section-5.2.3.7
+        protocol.subpacket_byte(0x0B, 9),  # preferred symmetric algo (AES-256)
+        # https://tools.ietf.org/html/rfc4880#section-5.2.3.4
+        protocol.subpacket_byte(0x1B, 1 | 2),  # key flags (certify & sign)
+        # https://tools.ietf.org/html/rfc4880#section-5.2.3.21
+        protocol.subpacket_byte(0x15, 8),  # preferred hash (SHA256)
+        # https://tools.ietf.org/html/rfc4880#section-5.2.3.8
+        protocol.subpacket_byte(0x16, 0),  # preferred compression (none)
+        # https://tools.ietf.org/html/rfc4880#section-5.2.3.9
+        protocol.subpacket_byte(0x17, 0x80)  # key server prefs (no-modify)
+        # https://tools.ietf.org/html/rfc4880#section-5.2.3.17
+    ]
+    unhashed_subpackets = [
+        protocol.subpacket(16, pubkey.key_id()),  # issuer key id
+        protocol.CUSTOM_SUBPACKET]
+
+    signature = protocol.make_signature(
+        signer_func=signer_func,
+        public_algo=pubkey.algo_id,
+        data_to_sign=data_to_sign,
+        sig_type=0x13,  # user id & public key
+        hashed_subpackets=hashed_subpackets,
+        unhashed_subpackets=unhashed_subpackets)
+
+    sign_packet = protocol.packet(tag=2, blob=signature)
+    return pubkey_packet + user_id_packet + sign_packet
+
+
+def create_subkey(primary_bytes, subkey, signer_func, secret_bytes=b''):
+    """Export new subkey to GPG primary key."""
+    subkey_packet = protocol.packet(tag=(7 if secret_bytes else 14),
+                                    blob=(subkey.data() + secret_bytes))
+    packets = list(decode.parse_packets(io.BytesIO(primary_bytes)))
+    primary, user_id, signature = packets[:3]
+
+    data_to_sign = primary['_to_hash'] + subkey.data_to_hash()
+
+    if subkey.ecdh:
+        embedded_sig = None
+    else:
+        # Primary Key Binding Signature
+        hashed_subpackets = [
+            protocol.subpacket_time(subkey.created)]  # signature time
+        unhashed_subpackets = [
+            protocol.subpacket(16, subkey.key_id())]  # issuer key id
+        embedded_sig = protocol.make_signature(
+            signer_func=signer_func,
+            data_to_sign=data_to_sign,
+            public_algo=subkey.algo_id,
+            sig_type=0x19,
+            hashed_subpackets=hashed_subpackets,
+            unhashed_subpackets=unhashed_subpackets)
+
+    # Subkey Binding Signature
+
+    # Key flags: https://tools.ietf.org/html/rfc4880#section-5.2.3.21
+    # (certify & sign)                   (encrypt)
+    flags = (2) if (not subkey.ecdh) else (4 | 8)
+
+    hashed_subpackets = [
+        protocol.subpacket_time(subkey.created),  # signature time
+        protocol.subpacket_byte(0x1B, flags)]
+
+    unhashed_subpackets = []
+    unhashed_subpackets.append(protocol.subpacket(16, primary['key_id']))
+    if embedded_sig is not None:
+        unhashed_subpackets.append(protocol.subpacket(32, embedded_sig))
+    unhashed_subpackets.append(protocol.CUSTOM_SUBPACKET)
+
+    if not decode.has_custom_subpacket(signature):
+        signer_func = keyring.create_agent_signer(user_id['value'])
+
+    signature = protocol.make_signature(
+        signer_func=signer_func,
+        data_to_sign=data_to_sign,
+        public_algo=primary['algo'],
+        sig_type=0x18,
+        hashed_subpackets=hashed_subpackets,
+        unhashed_subpackets=unhashed_subpackets)
+    sign_packet = protocol.packet(tag=2, blob=signature)
+    return primary_bytes + subkey_packet + sign_packet