token_flag = b"\x00"
msg = self.ephemeral_pubkey.to_bytes() + nonce + token_flag
return msg
def encrypt_auth_ack_message(self, ack_message: bytes) -> bytes:
if self.use_eip8:
auth_ack = encrypt_eip8_msg(ack_message, self.remote.pubkey)
else:
auth_ack = ecies.encrypt(ack_message, self.remote.pubkey)
return auth_ack
eip8_ack_sedes = sedes.List(
[
sedes.Binary(min_length=64, max_length=64), # ephemeral pubkey
sedes.Binary(min_length=32, max_length=32), # nonce
sedes.BigEndianInt(), # version
],
strict=False,
)
eip8_auth_sedes = sedes.List(
[
sedes.Binary(min_length=65, max_length=65), # sig
sedes.Binary(min_length=64, max_length=64), # pubkey
sedes.Binary(min_length=32, max_length=32), # nonce
sedes.BigEndianInt(), # version
],
strict=False,
)
def _pad_eip8_data(data: bytes) -> bytes:
class Status(Command):
_cmd_id = 0
decode_strict = False
# A list of (key, value) pairs is all a Status msg contains, but since the values can be of
# any type, we need to use the raw sedes here and do the actual deserialization in
# decode_payload().
structure = sedes.CountableList(sedes.List([sedes.binary, sedes.raw]))
# The sedes used for each key in the list above.
items_sedes = {
'protocolVersion':
sedes.big_endian_int,
'networkId':
sedes.big_endian_int,
'headTd':
sedes.big_endian_int,
'headHash':
sedes.binary,
'headNum':
sedes.big_endian_int,
'genesisHash':
sedes.binary,
'serveHeaders':
None,
'serveChainSince':
sedes.big_endian_int,
'serveStateSince':
sedes.big_endian_int,
'txRelay':
None,
'flowControl/BL':
sedes.big_endian_int,
'flowControl/MRC':
sedes.CountableList(
sedes.List([
sedes.big_endian_int, sedes.big_endian_int,
sedes.big_endian_int
])),
'flowControl/MRR':
sedes.big_endian_int,
}
@to_dict
def decode_payload(self, rlp_data):
data = super(Status, self).decode_payload(rlp_data)
# The LES/Status msg contains an arbitrary list of (key, value) pairs, where values can
# have different types and unknown keys should be ignored for forward compatibility
# reasons, so here we need an extra pass to deserialize each of the key/value pairs we
# know about.
for key, value in data:
# The sedes.binary we use in .structure above will give us a bytes value here, but
# using bytes as dictionary keys makes it impossible to use the dict() constructor
# with keyword arguments, so we convert them to strings here.
key = key.decode('ascii')
if key not in self.items_sedes:
continue
item_sedes = self.items_sedes[key]
if item_sedes is not None:
yield key, item_sedes.deserialize(value)
else:
yield key, value
def encode_payload(self, data):
response = [(key, self.items_sedes[key].serialize(value))
for key, value in sorted(data.items())]
return super(Status, self).encode_payload(response)
def as_head_info(self, decoded: _DecodedMsgType) -> HeadInfo:
return HeadInfo(
block_number=decoded['headNum'],
block_hash=decoded['headHash'],
total_difficulty=decoded['headTd'],
reorg_depth=0,
)
class NewBlockHashes(BaseCommand[Tuple[NewBlockHash, ...]]):
protocol_command_id = 1
serialization_codec: RLPCodec[Tuple[NewBlockHash, ...]] = RLPCodec(
sedes=sedes.CountableList(sedes.List([hash_sedes, sedes.big_endian_int])),
process_inbound_payload_fn=apply_formatter_to_array(lambda args: NewBlockHash(*args)),
)
class Status(Command):
_cmd_id = 0
decode_strict = False
# A list of (key, value) pairs is all a Status msg contains, but since the values can be of
# any type, we need to use the raw sedes here and do the actual deserialization in
# decode_payload().
structure = sedes.CountableList(sedes.List([sedes.text, sedes.raw]))
# The sedes used for each key in the list above. Keys that use None as their sedes are
# optional and have no value -- IOW, they just need to be present in the msg when appropriate.
items_sedes = {
'protocolVersion':
sedes.big_endian_int,
'networkId':
sedes.big_endian_int,
'headTd':
sedes.big_endian_int,
'headHash':
sedes.binary,
'headNum':
sedes.big_endian_int,
'genesisHash':
sedes.binary,
'serveHeaders':
None,
'serveChainSince':
sedes.big_endian_int,
'serveStateSince':
sedes.big_endian_int,
'txRelay':
None,
'flowControl/BL':
sedes.big_endian_int,
'flowControl/MRC':
sedes.CountableList(
sedes.List([
sedes.big_endian_int, sedes.big_endian_int,
sedes.big_endian_int
])),
'flowControl/MRR':
sedes.big_endian_int,
}
@to_dict
def decode_payload(self, rlp_data: bytes) -> Iterator[Tuple[str, Any]]:
data = cast(List[Tuple[str, bytes]], super().decode_payload(rlp_data))
# The LES/Status msg contains an arbitrary list of (key, value) pairs, where values can
# have different types and unknown keys should be ignored for forward compatibility
# reasons, so here we need an extra pass to deserialize each of the key/value pairs we
# know about.
for key, value in data:
if key not in self.items_sedes:
continue
yield key, self._deserialize_item(key, value)
def encode_payload(self, data: Union[Payload,
sedes.CountableList]) -> bytes:
response = [
(key, self._serialize_item(key, value))
for key, value in sorted(cast(Dict[str, Any], data).items())
]
return super().encode_payload(response)
def _deserialize_item(self, key: str, value: bytes) -> Any:
sedes = self.items_sedes[key]
if sedes is not None:
return sedes.deserialize(value)
else:
# See comment in the definition of item_sedes as to why we do this.
return b''
def _serialize_item(self, key: str, value: bytes) -> bytes:
sedes = self.items_sedes[key]
if sedes is not None:
return sedes.serialize(value)
else:
# See comment in the definition of item_sedes as to why we do this.
return b''
from trinity.rlp.block_body import BlockBody
from trinity.rlp.sedes import HashOrNumber, hash_sedes
from .forkid import ForkID
from .payloads import (
StatusV63Payload,
NewBlockHash,
BlockFields,
NewBlockPayload,
StatusPayload,
)
STATUS_V63_STRUCTURE = sedes.List((
sedes.big_endian_int,
sedes.big_endian_int,
sedes.big_endian_int,
hash_sedes,
hash_sedes,
))
class StatusV63(BaseCommand[StatusV63Payload]):
protocol_command_id = 0
serialization_codec: RLPCodec[StatusV63Payload] = RLPCodec(
sedes=STATUS_V63_STRUCTURE,
process_inbound_payload_fn=compose(
lambda args: StatusV63Payload(*args), ),
)
STATUS_STRUCTURE = sedes.List(
class NewBlockHashes(Command):
_cmd_id = 1
structure = sedes.CountableList(
sedes.List([sedes.binary, sedes.big_endian_int]))
class Status(Command):
_cmd_id = 0
decode_strict = False
# A list of (key, value) pairs is all a Status msg contains, but since the values can be of
# any type, we need to use the raw sedes here and do the actual deserialization in
# decode_payload().
structure = sedes.CountableList(sedes.List([sedes.text, sedes.raw]))
# The sedes used for each key in the list above.
items_sedes = {
'protocolVersion':
sedes.big_endian_int,
'networkId':
sedes.big_endian_int,
'headTd':
sedes.big_endian_int,
'headHash':
sedes.binary,
'headNum':
sedes.big_endian_int,
'genesisHash':
sedes.binary,
'serveHeaders':
None,
'serveChainSince':
sedes.big_endian_int,
'serveStateSince':
sedes.big_endian_int,
'txRelay':
None,
'flowControl/BL':
sedes.big_endian_int,
'flowControl/MRC':
sedes.CountableList(
sedes.List([
sedes.big_endian_int, sedes.big_endian_int,
sedes.big_endian_int
])),
'flowControl/MRR':
sedes.big_endian_int,
}
@to_dict
def decode_payload(
self, rlp_data: bytes) -> Generator[Tuple[str, Any], None, None]:
data = cast(List[Tuple[str, bytes]], super().decode_payload(rlp_data))
# The LES/Status msg contains an arbitrary list of (key, value) pairs, where values can
# have different types and unknown keys should be ignored for forward compatibility
# reasons, so here we need an extra pass to deserialize each of the key/value pairs we
# know about.
for key, value in data:
if key not in self.items_sedes:
continue
item_sedes = self.items_sedes[key]
if item_sedes is not None:
yield key, item_sedes.deserialize(value)
else:
yield key, value
def encode_payload(
self, data: Union[_DecodedMsgType, sedes.CountableList]) -> bytes:
response = [
(key, self.items_sedes[key].serialize(value))
for key, value in sorted(data.items()) # type: ignore
]
return super().encode_payload(response)
def as_head_info(self, decoded: _DecodedMsgType) -> HeadInfo:
decoded = cast(Dict[str, Any], decoded)
return HeadInfo(
block_number=decoded['headNum'],
block_hash=decoded['headHash'],
total_difficulty=decoded['headTd'],
reorg_depth=0,
)
def test_handshake():
tv = test_values
initiator = RLPxSession(
ECCx(raw_privkey=tv['initiator_private_key']),
is_initiator=True,
ephemeral_privkey=tv['initiator_ephemeral_private_key'])
initiator_pubkey = initiator.ecc.raw_pubkey
responder = RLPxSession(
ECCx(raw_privkey=tv['receiver_private_key']),
ephemeral_privkey=tv['receiver_ephemeral_private_key'])
responder_pubkey = responder.ecc.raw_pubkey
# test encryption
_enc = initiator.encrypt_auth_message(tv['auth_plaintext'],
responder_pubkey)
assert len(_enc) == len(tv['auth_ciphertext'])
assert len(tv['auth_ciphertext']) == 113 + len(tv['auth_plaintext']) # len
# test auth_msg plain
auth_msg = initiator.create_auth_message(
remote_pubkey=responder_pubkey,
ephemeral_privkey=tv['initiator_ephemeral_private_key'],
nonce=tv['initiator_nonce'])
# test auth_msg plain
assert len(auth_msg) == len(tv['auth_plaintext']) == 194
assert auth_msg[65:] == tv['auth_plaintext'][
65:] # starts with non deterministic k
_auth_msg_cipher = initiator.encrypt_auth_message(auth_msg,
responder_pubkey)
# test shared
responder.ecc.get_ecdh_key(initiator_pubkey) == \
initiator.ecc.get_ecdh_key(responder_pubkey)
# test decrypt
assert auth_msg == responder.ecc.ecies_decrypt(_auth_msg_cipher)
# check receive
responder_ephemeral_pubkey = privtopub(
tv['receiver_ephemeral_private_key'])
auth_msg_cipher = tv['auth_ciphertext']
auth_msg = responder.ecc.ecies_decrypt(auth_msg_cipher)
assert auth_msg[65:] == tv['auth_plaintext'][
65:] # starts with non deterministic k
responder.decode_authentication(auth_msg_cipher)
auth_ack_msg = responder.create_auth_ack_message(
responder_ephemeral_pubkey, nonce=tv['receiver_nonce'])
assert auth_ack_msg == tv['authresp_plaintext']
auth_ack_msg_cipher = responder.encrypt_auth_ack_message(
auth_ack_msg, remote_pubkey=responder.remote_pubkey)
# set auth ack msg cipher (needed later for mac calculation)
responder.auth_ack = tv['authresp_ciphertext']
responder.setup_cipher()
assert responder.ecdhe_shared_secret == tv['ecdhe_shared_secret']
assert len(responder.token) == len(tv['token'])
assert responder.token == tv['token']
assert responder.aes_secret == tv['aes_secret']
assert responder.mac_secret == tv['mac_secret']
assert responder.initiator_nonce == tv['initiator_nonce']
assert responder.responder_nonce == tv['receiver_nonce']
assert responder.auth_init == tv['auth_ciphertext']
assert responder.auth_ack == tv['authresp_ciphertext']
# test values are from initiator perspective?
assert responder.ingress_mac.digest() == tv['initial_egress_MAC']
assert responder.ingress_mac.digest() == tv['initial_egress_MAC']
assert responder.egress_mac.digest() == tv['initial_ingress_MAC']
assert responder.egress_mac.digest() == tv['initial_ingress_MAC']
r = responder.decrypt(tv['initiator_hello_packet'])
# unpack hello packet
import struct
import rlp
import rlp.sedes as sedes
from rlp.codec import consume_item
header = r['header']
frame_length = struct.unpack(b'>I', b'\x00' + header[:3])[0]
header_sedes = sedes.List([sedes.big_endian_int, sedes.big_endian_int])
header_data = rlp.decode(header[3:], strict=False, sedes=header_sedes)
print('header', repr(header_data))
# frame
frame = r['frame']
# normal: rlp(packet-type) [|| rlp(packet-data)] || padding
packet_type, end = consume_item(frame, start=0)
packet_type = rlp.decode(frame, sedes=sedes.big_endian_int, strict=False)
print('packet_type', repr(packet_type))
# decode hello body
_sedes_capabilites_tuple = sedes.List([sedes.binary, sedes.big_endian_int])
structure = [('version', sedes.big_endian_int),
('client_version_string', sedes.big_endian_int),
('capabilities',
sedes.CountableList(_sedes_capabilites_tuple)),
('listen_port', sedes.big_endian_int),
('remote_pubkey', sedes.binary)]
hello_sedes = sedes.List([x[1] for x in structure])
frame_data = rlp.decode(frame[end:], sedes=hello_sedes)
frame_data = dict((structure[i][0], x) for i, x in enumerate(frame_data))
print('frame', frame_data)
'serveChainSince':
sedes.big_endian_int,
'serveRecentChain':
sedes.big_endian_int,
'serveStateSince':
sedes.big_endian_int,
'serveRecentState':
sedes.big_endian_int,
'txRelay':
None,
'flowControl/BL':
sedes.big_endian_int,
'flowControl/MRC':
sedes.CountableList(
sedes.List(
[sedes.big_endian_int, sedes.big_endian_int,
sedes.big_endian_int])),
'flowControl/MRR':
sedes.big_endian_int,
}
STATUS_STRUCTURE = sedes.CountableList(sedes.List([sedes.text, sedes.raw]))
class StatusSerializationCodec(SerializationCodecAPI[StatusPayload]):
item_sedes: ClassVar[Dict[str, Any]]
@to_tuple
def _encode_items(self, *items: Tuple[str,
Any]) -> Iterable[Tuple[str, bytes]]:
for key, value in items:
class RLPxSession(object):
ephemeral_ecc = None
remote_ephemeral_pubkey = None
initiator_nonce = None
responder_nonce = None
auth_init = None
auth_ack = None
aes_secret = None
token = None
aes_enc = None
aes_dec = None
mac_enc = None
egress_mac = None
ingress_mac = None
is_ready = False
remote_pubkey = None
remote_version = 0
got_eip8_auth, got_eip8_ack = False, False
def __init__(self, ecc, is_initiator=False, ephemeral_privkey=None):
self.ecc = ecc
self.is_initiator = is_initiator
self.ephemeral_ecc = ECCx(raw_privkey=ephemeral_privkey)
### frame handling
def encrypt(self, header, frame):
assert self.is_ready is True
assert len(header) == 16
assert len(frame) % 16 == 0
def aes(data=''):
return self.aes_enc.update(data)
def mac(data=''):
self.egress_mac.update(data)
return self.egress_mac.digest()
# header
header_ciphertext = aes(header)
assert len(header_ciphertext) == 16
# egress-mac.update(aes(mac-secret,egress-mac) ^ header-ciphertext).digest
header_mac = mac(sxor(self.mac_enc(mac()[:16]),
header_ciphertext))[:16]
# frame
frame_ciphertext = aes(frame)
assert len(frame_ciphertext) == len(frame)
# egress-mac.update(aes(mac-secret,egress-mac) ^
# left128(egress-mac.update(frame-ciphertext).digest))
fmac_seed = mac(frame_ciphertext)
frame_mac = mac(sxor(self.mac_enc(mac()[:16]), fmac_seed[:16]))[:16]
return header_ciphertext + header_mac + frame_ciphertext + frame_mac
def decrypt_header(self, data):
assert self.is_ready is True
assert len(data) == 32
def aes(data=''):
return self.aes_dec.update(data)
def mac(data=''):
self.ingress_mac.update(data)
return self.ingress_mac.digest()
header_ciphertext = data[:16]
header_mac = data[16:32]
# ingress-mac.update(aes(mac-secret,ingress-mac) ^ header-ciphertext).digest
expected_header_mac = mac(
sxor(self.mac_enc(mac()[:16]), header_ciphertext))[:16]
# expected_header_mac = self.updateMAC(self.ingress_mac, header_ciphertext)
if not expected_header_mac == header_mac:
raise AuthenticationError('invalid header mac')
return aes(header_ciphertext)
def decrypt_body(self, data, body_size):
assert self.is_ready is True
def aes(data=''):
return self.aes_dec.update(data)
def mac(data=''):
self.ingress_mac.update(data)
return self.ingress_mac.digest()
# frame-size: 3-byte integer size of frame, big endian encoded (excludes padding)
# frame relates to body w/o padding w/o mac
read_size = ceil16(body_size)
if not len(data) >= read_size + 16:
raise FormatError('insufficient body length')
# FIXME check frame length in header
# assume datalen == framelen for now
frame_ciphertext = data[:read_size]
frame_mac = data[read_size:read_size + 16]
assert len(frame_mac) == 16
# ingres-mac.update(aes(mac-secret,ingres-mac) ^
# left128(ingres-mac.update(frame-ciphertext).digest))
fmac_seed = mac(frame_ciphertext)
expected_frame_mac = mac(sxor(self.mac_enc(mac()[:16]),
fmac_seed[:16]))[:16]
if not frame_mac == expected_frame_mac:
raise AuthenticationError('invalid frame mac')
return aes(frame_ciphertext)[:body_size]
def decrypt(self, data):
header = self.decrypt_header(data[:32])
body_size = struct.unpack('>I', '\x00' + header[:3])[0]
if not len(data) >= 32 + ceil16(body_size) + 16:
raise FormatError('insufficient body length')
frame = self.decrypt_body(data[32:], body_size)
return dict(header=header,
frame=frame,
bytes_read=32 + ceil16(len(frame)) + 16)
### handshake auth message handling
def create_auth_message(self,
remote_pubkey,
ephemeral_privkey=None,
nonce=None):
"""
1. initiator generates ecdhe-random and nonce and creates auth
2. initiator connects to remote and sends auth
New:
E(remote-pubk,
S(ephemeral-privk, ecdh-shared-secret ^ nonce) ||
H(ephemeral-pubk) || pubk || nonce || 0x0
)
Known:
E(remote-pubk,
S(ephemeral-privk, token ^ nonce) || H(ephemeral-pubk) || pubk || nonce || 0x1)
"""
assert self.is_initiator
if not self.ecc.is_valid_key(remote_pubkey):
raise InvalidKeyError('invalid remote pubkey')
self.remote_pubkey = remote_pubkey
ecdh_shared_secret = self.ecc.get_ecdh_key(remote_pubkey)
token = ecdh_shared_secret
flag = 0x0
self.initiator_nonce = nonce or sha3(
ienc(random.randint(0, 2**256 - 1)))
assert len(self.initiator_nonce) == 32
token_xor_nonce = sxor(token, self.initiator_nonce)
assert len(token_xor_nonce) == 32
ephemeral_pubkey = self.ephemeral_ecc.raw_pubkey
assert len(ephemeral_pubkey) == 512 / 8
if not self.ecc.is_valid_key(ephemeral_pubkey):
raise InvalidKeyError('invalid ephemeral pubkey')
# S(ephemeral-privk, ecdh-shared-secret ^ nonce)
S = self.ephemeral_ecc.sign(token_xor_nonce)
assert len(S) == 65
# S || H(ephemeral-pubk) || pubk || nonce || 0x0
auth_message = S + sha3(ephemeral_pubkey) + self.ecc.raw_pubkey + \
self.initiator_nonce + chr(flag)
assert len(auth_message) == 65 + 32 + 64 + 32 + 1 == 194
return auth_message
eip8_auth_sedes = sedes.List(
[
sedes.Binary(min_length=65, max_length=65), # sig
sedes.Binary(min_length=64, max_length=64), # pubkey
sedes.Binary(min_length=32, max_length=32), # nonce
sedes.BigEndianInt() # version
],
strict=False)
def encrypt_auth_message(self, auth_message, remote_pubkey=None):
assert self.is_initiator
remote_pubkey = remote_pubkey or self.remote_pubkey
self.auth_init = self.ecc.ecies_encrypt(auth_message, remote_pubkey)
assert len(self.auth_init) == 307
return self.auth_init
def decode_authentication(self, ciphertext):
"""
3. optionally, remote decrypts and verifies auth
(checks that recovery of signature == H(ephemeral-pubk))
4. remote generates authAck from remote-ephemeral-pubk and nonce
(authAck = authRecipient handshake)
optional: remote derives secrets and preemptively sends protocol-handshake (steps 9,11,8,10)
"""
assert not self.is_initiator
assert len(ciphertext) >= 307
try:
(size, sig, initiator_pubkey, nonce,
version) = self.decode_auth_plain(ciphertext)
except AuthenticationError:
(size, sig, initiator_pubkey, nonce,
version) = self.decode_auth_eip8(ciphertext)
self.got_eip8_auth = True
self.auth_init = ciphertext[:size]
# recover initiator ephemeral pubkey from sig
# S(ephemeral-privk, ecdh-shared-secret ^ nonce)
token = self.ecc.get_ecdh_key(initiator_pubkey)
self.remote_ephemeral_pubkey = ecdsa_recover(sxor(token, nonce), sig)
if not self.ecc.is_valid_key(self.remote_ephemeral_pubkey):
raise InvalidKeyError('invalid remote ephemeral pubkey')
self.initiator_nonce = nonce
self.remote_pubkey = initiator_pubkey
self.remote_version = version
return ciphertext[size:]
def decode_auth_plain(self, ciphertext):
"""
decode legacy pre-EIP-8 auth message format
"""
try:
message = self.ecc.ecies_decrypt(ciphertext[:307])
except RuntimeError as e:
raise AuthenticationError(e)
assert len(message) == 194
signature = message[:65]
pubkey = message[65 + 32:65 + 32 + 64]
if not self.ecc.is_valid_key(pubkey):
raise InvalidKeyError('invalid initiator pubkey')
nonce = message[65 + 32 + 64:65 + 32 + 64 + 32]
known_flag = bool(ord(message[65 + 32 + 64 + 32:]))
assert known_flag == 0
return (307, signature, pubkey, nonce, 4)
def decode_auth_eip8(self, ciphertext):
"""
decode EIP-8 auth message format
"""
size = struct.unpack('>H', ciphertext[:2])[0] + 2
assert len(ciphertext) >= size
try:
message = self.ecc.ecies_decrypt(ciphertext[2:size],
shared_mac_data=ciphertext[:2])
except RuntimeError as e:
raise AuthenticationError(e)
values = rlp.decode(message, sedes=self.eip8_auth_sedes, strict=False)
assert len(values) >= 4
return (size, ) + values[:4]
### handshake ack message handling
def create_auth_ack_message(self,
version=supported_rlpx_version,
eip8=False,
ephemeral_pubkey=None,
nonce=None):
"""
authRecipient = E(remote-pubk, remote-ephemeral-pubk || nonce || 0x1) // token found
authRecipient = E(remote-pubk, remote-ephemeral-pubk || nonce || 0x0) // token not found
nonce, ephemeral_pubkey, version are local!
"""
assert not self.is_initiator
ephemeral_pubkey = ephemeral_pubkey or self.ephemeral_ecc.raw_pubkey
self.responder_nonce = nonce or sha3(
ienc(random.randint(0, 2**256 - 1)))
if eip8 or self.got_eip8_auth:
msg = self.create_eip8_auth_ack_message(ephemeral_pubkey,
self.responder_nonce,
version)
assert len(msg) > 97
else:
msg = ephemeral_pubkey + self.responder_nonce + '\x00'
assert len(msg) == 97
return msg
eip8_ack_sedes = sedes.List(
[
sedes.Binary(min_length=64, max_length=64), # ephemeral pubkey
sedes.Binary(min_length=32, max_length=32), # nonce
sedes.BigEndianInt() # version
],
strict=False)
def create_eip8_auth_ack_message(self, ephemeral_pubkey, nonce, version):
data = rlp.encode((ephemeral_pubkey, nonce, version),
sedes=self.eip8_ack_sedes)
pad = os.urandom(random.randint(100, 250))
return data + pad
def encrypt_auth_ack_message(self,
ack_message,
eip8=False,
remote_pubkey=None):
assert not self.is_initiator
remote_pubkey = remote_pubkey or self.remote_pubkey
if eip8 or self.got_eip8_auth:
# The EIP-8 version has an authenticated length prefix.
prefix = struct.pack(
'>H',
len(ack_message) + self.ecc.ecies_encrypt_overhead_length)
self.auth_ack = self.ecc.ecies_encrypt(ack_message,
remote_pubkey,
shared_mac_data=prefix)
self.auth_ack = prefix + self.auth_ack
else:
self.auth_ack = self.ecc.ecies_encrypt(ack_message, remote_pubkey)
assert len(self.auth_ack) == 210
return self.auth_ack
def decode_auth_ack_message(self, ciphertext):
assert self.is_initiator
assert len(ciphertext) >= 210
try:
(size, eph_pubkey, nonce,
version) = self.decode_ack_plain(ciphertext)
except AuthenticationError:
(size, eph_pubkey, nonce,
version) = self.decode_ack_eip8(ciphertext)
self.got_eip8_ack = True
self.auth_ack = ciphertext[:size]
self.remote_ephemeral_pubkey = eph_pubkey[:64]
self.responder_nonce = nonce
self.remote_version = version
if not self.ecc.is_valid_key(self.remote_ephemeral_pubkey):
raise InvalidKeyError('invalid remote ephemeral pubkey')
return ciphertext[size:]
def decode_ack_plain(self, ciphertext):
"""
decode legacy pre-EIP-8 ack message format
"""
try:
message = self.ecc.ecies_decrypt(ciphertext[:210])
except RuntimeError as e:
raise AuthenticationError(e)
assert len(message) == 64 + 32 + 1
eph_pubkey = message[:64]
nonce = message[64:64 + 32]
known = ord(message[-1])
assert known == 0
return (210, eph_pubkey, nonce, 4)
def decode_ack_eip8(self, ciphertext):
"""
decode EIP-8 ack message format
"""
size = struct.unpack('>H', ciphertext[:2])[0] + 2
assert len(ciphertext) == size
try:
message = self.ecc.ecies_decrypt(ciphertext[2:size],
shared_mac_data=ciphertext[:2])
except RuntimeError as e:
raise AuthenticationError(e)
values = rlp.decode(message, sedes=self.eip8_ack_sedes, strict=False)
assert len(values) >= 3
return (size, ) + values[:3]
### handshake key derivation
def setup_cipher(self):
assert self.responder_nonce
assert self.initiator_nonce
assert self.auth_init
assert self.auth_ack
assert self.remote_ephemeral_pubkey
if not self.ecc.is_valid_key(self.remote_ephemeral_pubkey):
raise InvalidKeyError('invalid remote ephemeral pubkey')
# derive base secrets from ephemeral key agreement
# ecdhe-shared-secret = ecdh.agree(ephemeral-privkey, remote-ephemeral-pubk)
ecdhe_shared_secret = self.ephemeral_ecc.get_ecdh_key(
self.remote_ephemeral_pubkey)
# shared-secret = sha3(ecdhe-shared-secret || sha3(nonce || initiator-nonce))
shared_secret = sha3(ecdhe_shared_secret +
sha3(self.responder_nonce + self.initiator_nonce))
self.ecdhe_shared_secret = ecdhe_shared_secret # used in tests
self.shared_secret = shared_secret # used in tests
# token = sha3(shared-secret)
self.token = sha3(shared_secret)
# aes-secret = sha3(ecdhe-shared-secret || shared-secret)
self.aes_secret = sha3(ecdhe_shared_secret + shared_secret)
# mac-secret = sha3(ecdhe-shared-secret || aes-secret)
self.mac_secret = sha3(ecdhe_shared_secret + self.aes_secret)
# setup sha3 instances for the MACs
# egress-mac = sha3.update(mac-secret ^ recipient-nonce || auth-sent-init)
mac1 = sha3_256(
sxor(self.mac_secret, self.responder_nonce) + self.auth_init)
# ingress-mac = sha3.update(mac-secret ^ initiator-nonce || auth-recvd-ack)
mac2 = sha3_256(
sxor(self.mac_secret, self.initiator_nonce) + self.auth_ack)
if self.is_initiator:
self.egress_mac, self.ingress_mac = mac1, mac2
else:
self.egress_mac, self.ingress_mac = mac2, mac1
ciphername = 'aes-256-ctr'
iv = "\x00" * 16
assert len(iv) == 16
self.aes_enc = pyelliptic.Cipher(self.aes_secret,
iv,
1,
ciphername=ciphername)
self.aes_dec = pyelliptic.Cipher(self.aes_secret,
iv,
0,
ciphername=ciphername)
self.mac_enc = AES.new(self.mac_secret, AES.MODE_ECB).encrypt
self.is_ready = True
