def make(cls):
private = ec.generate_private_key(ec.SECP256K1(), default_backend())
public_bytes = private.public_key().public_bytes(
Encoding.X962, PublicFormat.UncompressedPoint)
private_num = private.private_numbers().private_value
private_bytes = pad32(int_to_big(private_num))
return cls(private_bytes, public_bytes[1:])
def recover(hashes: bytes, sig_vrs):
r, s, v = sig_vrs
v = v + 33
# todo range exception
x = r
a = (x * x * x + CURVE.A * x + CURVE.B) % CURVE.P
b = pow(a, (CURVE.P + 1) // 4, CURVE.P)
y = b if (b - (v % 2)) % 2 == 0 else CURVE.P - b
e = int_from_big(hashes)
mg = ec_mul((CURVE.Gx, CURVE.Gy, 1), (CURVE.N - e) % CURVE.N)
xy = ec_mul((x, y, 1), s)
_xy = ec_add(mg, xy)
Q = ec_mul(_xy, ec_inv(r, CURVE.N))
p, q = from_jacob(Q)
return b''.join((pad32(int_to_big(p)), pad32(int_to_big(q))))
def _encode(data):
if isinstance(data, Serializer):
payload = b''.join(_encode(field) for field in data)
offset_type = 216 # obj
elif isinstance(data, bytes):
payload = pad32(data)
offset_type = 27 # data
prefix = encode_prefix(len(data), offset_type)
return prefix + payload
async def accept_handshake(reader: asyncio.StreamReader,
writer: asyncio.StreamWriter, keys, cipher: bytes):
exchange_random, ephem_pubkey, pubkey = _accept_decode_secret(keys, cipher)
address, port, *_ = writer.get_extra_info('peername')
endpoint = EndPoint.make(pubkey, address, port)
# responder [keys, endpoint, token, (bool) got eip8]
random = os.urandom(16)
random_secret = sha3_256(random).digest()
sequence = pad32(int_to_big32(1))
ephemeral_keys = ecies.generate_random()
payload = encode_payload(sequence, ephemeral_keys.public_bytes,
random_secret)
cipher = ecies.encrypt(payload, pubkey)
return endpoint
async def _handshake_shared_secret(reader: asyncio.StreamReader,
writer: asyncio.StreamWriter,
endpoint: EndPoint, keys, token):
ephemeral_keys = ecies.generate_random()
shared_secret = ecies.make_shared_secret(keys.private_bytes,
endpoint.pubkey)
random = os.urandom(16)
random_secret = sha3_256(random).digest()
sequence = pad32(int_to_big32(0))
exchange_secret = sha3_256(shared_secret + random_secret +
sequence).digest()
sig = ephemeral_keys.sign(exchange_secret)
encode_sig = encode_signature(sig)
# --- temporary
version = pad16(int_to_big16(1))
handshake_suffix = pad16(int_to_big16(0))
# --------------------------------------------- #
payload = encode_payload(sequence, encode_sig, keys.public_bytes,
random_secret, version, handshake_suffix)
cipher = ecies.encrypt(ephemeral_keys.public_bytes, payload)
if writer.is_closing():
raise ConnectionError(
'during open_connection handling, connection closed')
writer.write(cipher)
await writer.drain()
token.cancellable_wait(reader.read(169), timeout=5)
if reader.at_eof():
raise ConnectionError('disconnected')
def handshake_flows():
# $ exchange keys $ #
# peer private, public
my_keys = ecies.generate_random()
# ephemeral private, public
my_ephem_keys = ecies.generate_random()
# stranger key
keys = ecies.generate_random()
# *-- connect --* #
# my private key, stranger public key = shared secret
shared_secret = ecies.make_shared_secret(my_keys.private_bytes,
keys.public_bytes)
random = os.urandom(16)
nonce = sha3_256(random).digest()
seq = pad32(int_to_big(0))
secret = sha3_256(shared_secret + nonce + seq).digest()
s = my_ephem_keys.sign(secret)
encode_sig = encode_signature(s)
# 65, 65, 32, 4, 4
# signature, public, nonce, version, suffix (170): handshake messages
encode_payload = b''.join((seq, encode_sig, my_keys.public_bytes, nonce,
pad16(int_to_big(1)), pad16(int_to_big(0))))
cipher = ecies.encrypt(keys.public_bytes, encode_payload)
# -------------------------------------------------------------------------------#
# *-- accept --* #
plain = ecies.decrypt(keys.private_bytes, cipher)
if plain != encode_payload:
raise ValueError('plain != payload')
if len(plain) != 169:
raise ValueError('payload size error', len(plain))
# decode payload
seqe = plain[:4]
plain = plain[4:]
accept_sig = plain[:65]
accept_public = plain[65:129]
accept_nonce = plain[129:161]
ve, suff = plain[-4:-2], plain[-2:]
if ve != b'\x00\x01':
raise ValueError
if suff != b'\x00\x00':
raise ValueError
# stranger private key, my public key = shared secret
stranger_shared_secret = ecies.make_shared_secret(keys.private_bytes,
accept_public)
accept_secret = sha3_256(stranger_shared_secret + accept_nonce +
seqe).digest()
if accept_secret != secret:
raise ValueError
decode_sig = decode_signature(accept_sig)
if s != decode_sig:
raise ValueError
accept_ephem_key = recover(accept_secret, decode_sig)
handshake_sset = (accept_ephem_key, accept_nonce, accept_public)
print('verifies:', verifies(accept_secret, decode_sig[:2],
accept_ephem_key))
def encode_signature(sig_vrs):
r, s, v = sig_vrs
r_bytes = pad32(int_to_big(r))
s_bytes = pad32(int_to_big(s))
v_bytes = int_to_big(v)
return b''.join((r_bytes, s_bytes, v_bytes))
def encode_payload(body, mackey, shared, pubkey):
body_size = pad32(int_to_big(len(body)))
checksum = sha3_256_mac(mackey, body + body_size + shared)
payload = [b'\x04' + pubkey, checksum, body, body_size]
return b''.join(payload)
