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=b''):
data = str_to_bytes(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=b''):
data = str_to_bytes(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=b''):
data = str_to_bytes(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(b'>I', b'\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 + ascii_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
if len(ciphertext) < 307:
raise FormatError("Ciphertext too short")
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(safe_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
if len(ciphertext) < size:
raise FormatError("Message shorter than specified 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 + b'\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 = safe_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
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_token_found = False
remote_pubkey = None
auth_message_length = 194
auth_message_ct_length = auth_message_length + ECCx.ecies_encrypt_overhead_length
auth_ack_message_length = 97
auth_ack_message_ct_length = auth_ack_message_length + ECCx.ecies_encrypt_overhead_length
def __init__(self, ecc, is_initiator=False, token_by_pubkey=dict(), ephemeral_privkey=None):
self.ecc = ecc
self.is_initiator = is_initiator
self.token_by_pubkey = token_by_pubkey
self.ephemeral_ecc = ECCx(raw_privkey=ephemeral_privkey)
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)
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
token = self.token_by_pubkey.get(remote_pubkey)
if not token: # new
ecdh_shared_secret = self.ecc.get_ecdh_key(remote_pubkey)
token = ecdh_shared_secret
flag = 0x0
else:
flag = 0x1
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
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) == self.auth_message_ct_length
return self.auth_init
def encrypt_auth_ack_message(self, auth_message, remote_pubkey=None):
assert not self.is_initiator
remote_pubkey = remote_pubkey or self.remote_pubkey
self.auth_ack = self.ecc.ecies_encrypt(auth_message, remote_pubkey)
assert len(self.auth_ack) == self.auth_ack_message_ct_length
return self.auth_ack
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
self.auth_init = ciphertext
try:
auth_message = self.ecc.ecies_decrypt(ciphertext)
except RuntimeError as e:
raise AuthenticationError(e)
# S || H(ephemeral-pubk) || pubk || nonce || 0x[0|1]
assert len(auth_message) == 65 + 32 + 64 + 32 + 1 == 194 == self.auth_message_length
signature = auth_message[:65]
H_initiator_ephemeral_pubkey = auth_message[65:65 + 32]
initiator_pubkey = auth_message[65 + 32:65 + 32 + 64]
if not self.ecc.is_valid_key(initiator_pubkey):
raise InvalidKeyError('invalid initiator pubkey')
self.remote_pubkey = initiator_pubkey
self.initiator_nonce = auth_message[65 + 32 + 64:65 + 32 + 64 + 32]
known_flag = bool(ord(auth_message[65 + 32 + 64 + 32:]))
# token or new ecdh_shared_secret
if known_flag:
self.remote_token_found = True
# what todo if remote has token, but local forgot it.
# reply with token not found. FIXME!!!
token = self.token_by_pubkey.get(initiator_pubkey)
assert token # FIXME continue session with ecdh_key and send flag in auth_ack
else:
token = self.ecc.get_ecdh_key(initiator_pubkey)
# verify auth
# S(ephemeral-privk, ecdh-shared-secret ^ nonce)
signed = sxor(token, self.initiator_nonce)
# recover initiator ephemeral pubkey
self.remote_ephemeral_pubkey = ecdsa_recover(signed, signature)
if not self.ecc.is_valid_key(self.remote_ephemeral_pubkey):
raise InvalidKeyError('invalid remote ephemeral pubkey')
if not ecdsa_verify(self.remote_ephemeral_pubkey, signature, signed):
raise AuthenticationError('could not verify signature')
# checks that recovery of signature == H(ephemeral-pubk)
assert H_initiator_ephemeral_pubkey == sha3(self.remote_ephemeral_pubkey)
def create_auth_ack_message(self, ephemeral_pubkey=None, nonce=None, token_found=False):
"""
authRecipient = E(remote-pubk, remote-ephemeral-pubk || nonce || 0x1) // token found
authRecipient = E(remote-pubk, remote-ephemeral-pubk || nonce || 0x0) // token not found
nonce and empehemeral-pubk 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)))
flag = chr(1 if token_found else 0)
msg = ephemeral_pubkey + self.responder_nonce + flag
assert len(msg) == 64 + 32 + 1 == 97 == self.auth_ack_message_length
return msg
def decode_auth_ack_message(self, ciphertext):
assert self.is_initiator
self.auth_ack = ciphertext
auth_ack_message = self.ecc.ecies_decrypt(ciphertext)
assert len(auth_ack_message) == 64 + 32 + 1
self.remote_ephemeral_pubkey = auth_ack_message[:64]
if not self.ecc.is_valid_key(self.remote_ephemeral_pubkey):
raise InvalidKeyError('invalid remote ephemeral pubkey')
self.responder_nonce = auth_ack_message[64:64 + 32]
self.remote_token_found = bool(ord(auth_ack_message[-1]))
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)
self.token_by_pubkey[self.remote_pubkey] = self.token
# 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.AESCipher(self.mac_secret, AES.MODE_ECB).encrypt
self.is_ready = True
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_token_found = False
remote_pubkey = None
auth_message_length = 194
auth_message_ct_length = auth_message_length + ECCx.ecies_encrypt_overhead_length
auth_ack_message_length = 97
auth_ack_message_ct_length = auth_ack_message_length + ECCx.ecies_encrypt_overhead_length
def __init__(self,
ecc,
is_initiator=False,
token_by_pubkey=dict(),
ephemeral_privkey=None):
self.ecc = ecc
self.is_initiator = is_initiator
self.token_by_pubkey = token_by_pubkey
self.ephemeral_ecc = ECCx(raw_privkey=ephemeral_privkey)
def encrypt(self, header, frame):
"""
# https://github.com/ethereum/go-ethereum/blob/develop/p2p/rlpx.go
# https://github.com/ethereum/cpp-ethereum/blob/develop/libp2p/RLPxFrameIO.cpp
"""
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]
# FIXME: how to restore mac if i received invalid data?
# 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)
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
token = self.token_by_pubkey.get(remote_pubkey)
if not token: # new
ecdh_shared_secret = self.ecc.get_ecdh_key(remote_pubkey)
token = ecdh_shared_secret
flag = 0x0
else:
flag = 0x1
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
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) == self.auth_message_ct_length
return self.auth_init
def encrypt_auth_ack_message(self, auth_message, remote_pubkey=None):
assert not self.is_initiator
remote_pubkey = remote_pubkey or self.remote_pubkey
self.auth_ack = self.ecc.ecies_encrypt(auth_message, remote_pubkey)
assert len(self.auth_ack) == self.auth_ack_message_ct_length
return self.auth_ack
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
self.auth_init = ciphertext
try:
auth_message = self.ecc.ecies_decrypt(ciphertext)
except RuntimeError as e:
raise AuthenticationError(e)
# S || H(ephemeral-pubk) || pubk || nonce || 0x[0|1]
assert len(
auth_message
) == 65 + 32 + 64 + 32 + 1 == 194 == self.auth_message_length
signature = auth_message[:65]
H_initiator_ephemeral_pubkey = auth_message[65:65 + 32]
initiator_pubkey = auth_message[65 + 32:65 + 32 + 64]
if not self.ecc.is_valid_key(initiator_pubkey):
raise InvalidKeyError('invalid initiator pubkey')
self.remote_pubkey = initiator_pubkey
self.initiator_nonce = auth_message[65 + 32 + 64:65 + 32 + 64 + 32]
known_flag = bool(ord(auth_message[65 + 32 + 64 + 32:]))
# token or new ecdh_shared_secret
if known_flag:
self.remote_token_found = True
# what todo if remote has token, but local forgot it.
# reply with token not found. FIXME!!!
token = self.token_by_pubkey.get(initiator_pubkey)
assert token # FIXME continue session with ecdh_key and send flag in auth_ack
else:
token = self.ecc.get_ecdh_key(initiator_pubkey)
# verify auth
# S(ephemeral-privk, ecdh-shared-secret ^ nonce)
signed = sxor(token, self.initiator_nonce)
# recover initiator ephemeral pubkey
self.remote_ephemeral_pubkey = ecdsa_recover(signed, signature)
if not self.ecc.is_valid_key(self.remote_ephemeral_pubkey):
raise InvalidKeyError('invalid remote ephemeral pubkey')
if not ecdsa_verify(self.remote_ephemeral_pubkey, signature, signed):
raise AuthenticationError('could not verify signature')
# checks that recovery of signature == H(ephemeral-pubk)
assert H_initiator_ephemeral_pubkey == sha3(
self.remote_ephemeral_pubkey)
def create_auth_ack_message(self,
ephemeral_pubkey=None,
nonce=None,
token_found=False):
"""
authRecipient = E(remote-pubk, remote-ephemeral-pubk || nonce || 0x1) // token found
authRecipient = E(remote-pubk, remote-ephemeral-pubk || nonce || 0x0) // token not found
nonce and empehemeral-pubk 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)))
flag = chr(1 if token_found else 0)
msg = ephemeral_pubkey + self.responder_nonce + flag
assert len(msg) == 64 + 32 + 1 == 97 == self.auth_ack_message_length
return msg
def decode_auth_ack_message(self, ciphertext):
assert self.is_initiator
self.auth_ack = ciphertext
auth_ack_message = self.ecc.ecies_decrypt(ciphertext)
assert len(auth_ack_message) == 64 + 32 + 1
self.remote_ephemeral_pubkey = auth_ack_message[:64]
if not self.ecc.is_valid_key(self.remote_ephemeral_pubkey):
raise InvalidKeyError('invalid remote ephemeral pubkey')
self.responder_nonce = auth_ack_message[64:64 + 32]
self.remote_token_found = bool(ord(auth_ack_message[-1]))
def setup_cipher(self):
# https://github.com/ethereum/cpp-ethereum/blob/develop/libp2p/RLPxFrameIO.cpp#L34
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 # FIXME DEBUG
self.shared_secret = shared_secret # FIXME DEBUG
# token = sha3(shared-secret)
self.token = sha3(shared_secret)
self.token_by_pubkey[self.remote_pubkey] = self.token
# 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.AESCipher(self.mac_secret, AES.MODE_ECB).encrypt
self.is_ready = True
class RLPxSession(object):
ephemeral_ecc = None
nonce = None
token = None
aes_secret = None
aes_enc = None
aes_dec = None
egress_mac = None
ingress_mac = None
remote_node = None
_authentication_sent = False
is_ready = False
def __init__(self, peer=None):
# persisted peer data. keys are the nodeid
# session data
self.peer = peer
if peer:
self.node = peer.local_node.ecc
else:
self.node = None
def __repr__(self):
return '<RLPxSession (%s)>' % self.address.encode('hex')
def encrypt(self, header, frame):
"""
header-mac: right128 of
egress-mac.update(aes(mac-secret,egress-mac)^header-ciphertext)
"""
assert self.is_ready is True
def aes(data):
return self.aes_enc.update(data)
def mac(data):
return self.egress_mac.update(data)
# header
assert len(header) == 16 # zero padded to 16 bytes
header_ciphertext = aes(header)
assert len(header_ciphertext) <= 32 # must not be larger than mac
# FIXME mac-secret!?
header_mac = mac(sxor(aes(mac('')), header_ciphertext))[-16:]
# frame
frame_ciphertext = aes(frame)
frame_mac = self.egress_mac.update(frame_ciphertext)
return header_ciphertext + header_mac + frame_ciphertext + frame_mac
def decrypt(self, data):
assert self.is_ready is True
def aes(data):
return self.aes_dec.update(data)
def mac(data):
return self.egress_mac.update(data)
header_ciphertext = data[:16]
header_mac = data[16:32]
header = aes(header_ciphertext)
expected_header_mac = mac(sxor(aes(mac(''), header_ciphertext)))[-16:]
assert expected_header_mac == header_mac
# FIXME check frame length in header
# assume datalen == framelen for now
frame_mac = self.egress_mac.update(frame_ciphertext)
data = aes(data[32:])
def create_auth_message(self,
remote_pubkey,
token=None,
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)
"""
if not token: # new
ecdh_shared_secret = self.node.get_ecdh_key(remote_pubkey)
token = ecdh_shared_secret
flag = 0x0
else:
flag = 0x1
nonce = nonce or ienc(random.randint(0, 2**256 - 1))
assert len(nonce) == 32
token_xor_nonce = sxor(token, nonce)
assert len(token_xor_nonce) == 32
# generate session ephemeral key
if not ephemeral_privkey:
ephemeral_privkey = sha3(ienc(random.randint(0, 2**256 - 1)))
self.ephemeral_ecc = ECCx(raw_privkey=ephemeral_privkey)
ephemeral_pubkey = self.ephemeral_ecc.raw_pubkey
assert len(ephemeral_pubkey) == 512 / 8
# 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.node.raw_pubkey + nonce + chr(flag)
assert len(auth_message) == 65 + 32 + 64 + 32 + 1 == 194
return auth_message
def encrypt_auth_message(self, auth_message, remote_pubkey):
return self.node.ecies_encrypt(auth_message, remote_pubkey)
encrypt_auth_ack_message = encrypt_auth_message
def send_authentication(self, remote_node, ephermal_privkey=None):
auth_message = self.create_auth_message(remote_node, ephermal_privkey)
self.peer.send(auth_message)
self._authentication_sent = True
def receive_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)
"""
auth_message = self.node.ecies_decrypt(ciphertext)
# S || H(ephemeral-pubk) || pubk || nonce || 0x[0|1]
assert len(auth_message) == 65 + 32 + 64 + 32 + 1 == 194
signature = auth_message[:65]
H_remote_ephemeral_pubkey = auth_message[65:65 + 32]
remote_pubkey = auth_message[65 + 32:65 + 32 + 64]
nonce = auth_message[65 + 32 + 64:65 + 32 + 64 + 32]
known_flag = auth_message[65 + 32 + 64 + 32:]
# token or new ecdh_shared_secret
token_database = dict() # FIXME
token_found = False
if known_flag == 1:
token = token_database.get(remote_pubkey)
if token:
token_found = True
else:
token = ecdh_shared_secret = self.node.get_ecdh_key(remote_pubkey)
# verify auth
# S(ephemeral-privk, ecdh-shared-secret ^ nonce)
ecdh_shared_secret = self.node.get_ecdh_key(remote_pubkey)
signed = sxor(ecdh_shared_secret, nonce)
# recover remote ephemeral pubkey
remote_ephemeral_pubkey = ecdsa_recover(signed, signature)
assert ecdsa_verify(remote_ephemeral_pubkey, signature, signed)
# checks that recovery of signature == H(ephemeral-pubk)
assert H_remote_ephemeral_pubkey == sha3(remote_ephemeral_pubkey)
return dict(remote_ephemeral_pubkey=remote_ephemeral_pubkey,
token=token,
token_found=token_found,
ecdh_shared_secret=ecdh_shared_secret,
remote_pubkey=remote_pubkey,
nonce=nonce,
known_flag=known_flag)
def create_auth_ack_message(self,
ephemeral_pubkey,
nonce,
token_found=False):
"""
authRecipient = E(remote-pubk, remote-ephemeral-pubk || nonce || 0x1) // token found
authRecipient = E(remote-pubk, remote-ephemeral-pubk || nonce || 0x0) // token not found
nonce and empehemeral-pubk are local!
"""
flag = chr(1 if token_found else 0)
msg = ephemeral_pubkey + nonce + flag
assert len(msg) == 64 + 32 + 1 == 97
return msg
def something():
##################
# send authentication if not yet
if not self._authentication_sent:
remote_node = RemoteNode(remote_pubkey) # FIXME LOOKUP
self.send_authentication(remote_node)
# - success -> AcknowledgeAuthentication
self.acknowledge_authentication(other, remote_pubkey,
remote_ecdhe_pubkey)
# ecdhe_shared_secret = ecdh.agree(ecdhe-random, ecdhe-random-public)
# Compute public key with the local private key and return a 512bits shared key
ecdhe_shared_secret = self.ephemeral_ecc.get_ecdh_key(remote_pubkey)
ecdhe_pubkey = self.ephemeral_ecc.get_pubkey()
# shared-secret = sha3(ecdhe-shared-secret || sha3(nonce || remote-nonce))
shared_secret = sha3(ecdhe_shared_secret +
sha3(ienc(self.nonce) + ienc(remote_nonce)))
self.aes_secret = sha3(ecdhe_shared_secret + shared_secret)
self.mac_secret = sha3(ecdhe_shared_secret + self.aes_secret)
# egress-mac = sha3(mac-secret^nonce || auth)
self.egress_mac = sha3(sxor(self.mac_secret, self.nonce) + ciphertext)
# ingress-mac = sha3(mac-secret^remote-nonce || auth)
self.ingress_mac = sha3(
sxor(self.mac_secret, remote_nonce) + ciphertext)
self.token = sha3(shared_secret)
iv = pyelliptic.Cipher.gen_IV('aes-256-ctr')
self.aes_enc = pyelliptic.Cipher(self.aes_secret,
iv,
1,
ciphername='aes-256-ctr')
self.aes_dec = pyelliptic.Cipher(self.aes_secret,
iv,
0,
ciphername='aes-256-ctr')
self.is_ready = True
