101 lines
2.6 KiB
Python
101 lines
2.6 KiB
Python
"""GPG protocol utilities."""
|
|
|
|
import logging
|
|
import struct
|
|
|
|
from .. import formats, util
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
|
|
def packet(tag, blob):
|
|
"""Create small GPG packet."""
|
|
assert len(blob) < 2**32
|
|
|
|
if len(blob) < 2**8:
|
|
length_type = 0
|
|
elif len(blob) < 2**16:
|
|
length_type = 1
|
|
else:
|
|
length_type = 2
|
|
|
|
fmt = ['>B', '>H', '>L'][length_type]
|
|
leading_byte = 0x80 | (tag << 2) | (length_type)
|
|
return struct.pack('>B', leading_byte) + util.prefix_len(fmt, blob)
|
|
|
|
|
|
def subpacket(subpacket_type, fmt, *values):
|
|
"""Create GPG subpacket."""
|
|
blob = struct.pack(fmt, *values) if values else fmt
|
|
return struct.pack('>B', subpacket_type) + blob
|
|
|
|
|
|
def subpacket_long(subpacket_type, value):
|
|
"""Create GPG subpacket with 32-bit unsigned integer."""
|
|
return subpacket(subpacket_type, '>L', value)
|
|
|
|
|
|
def subpacket_time(value):
|
|
"""Create GPG subpacket with time in seconds (since Epoch)."""
|
|
return subpacket_long(2, value)
|
|
|
|
|
|
def subpacket_byte(subpacket_type, value):
|
|
"""Create GPG subpacket with 8-bit unsigned integer."""
|
|
return subpacket(subpacket_type, '>B', value)
|
|
|
|
|
|
def subpackets(*items):
|
|
"""Serialize several GPG subpackets."""
|
|
prefixed = [util.prefix_len('>B', item) for item in items]
|
|
return util.prefix_len('>H', b''.join(prefixed))
|
|
|
|
|
|
def mpi(value):
|
|
"""Serialize multipresicion integer using GPG format."""
|
|
bits = value.bit_length()
|
|
data_size = (bits + 7) // 8
|
|
data_bytes = bytearray(data_size)
|
|
for i in range(data_size):
|
|
data_bytes[i] = value & 0xFF
|
|
value = value >> 8
|
|
|
|
data_bytes.reverse()
|
|
return struct.pack('>H', bits) + bytes(data_bytes)
|
|
|
|
|
|
def _serialize_nist256(vk):
|
|
return mpi((4 << 512) |
|
|
(vk.pubkey.point.x() << 256) |
|
|
(vk.pubkey.point.y()))
|
|
|
|
|
|
def _serialize_ed25519(vk):
|
|
return mpi((0x40 << 256) |
|
|
util.bytes2num(vk.to_bytes()))
|
|
|
|
|
|
SUPPORTED_CURVES = {
|
|
formats.CURVE_NIST256: {
|
|
# https://tools.ietf.org/html/rfc6637#section-11
|
|
'oid': b'\x2A\x86\x48\xCE\x3D\x03\x01\x07',
|
|
'algo_id': 19,
|
|
'serialize': _serialize_nist256
|
|
},
|
|
formats.CURVE_ED25519: {
|
|
'oid': b'\x2B\x06\x01\x04\x01\xDA\x47\x0F\x01',
|
|
'algo_id': 22,
|
|
'serialize': _serialize_ed25519
|
|
}
|
|
}
|
|
|
|
|
|
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."""
|
|
curve_name, = [name for name, info in SUPPORTED_CURVES.items()
|
|
if info['algo_id'] == algo_id]
|
|
return curve_name
|