def connection_made(self, transport):
super().connection_made(transport)
self.importKeys()
self.state = self.STATE_CLIENT_HELLO
self.clientNonce = self.generateNonce()
self.dbgPrint(
"Client: Sending Hello message, current state: {!r}, nonce number: {!r}".format(self.STATE_DESC[self.state],
self.clientNonce))
# Serialize certs to pack into PlsHello
certBytes = [CipherUtil.serializeCert(c) for c in self.certs]
helloPkt = PlsHello.makeHelloPacket(self.clientNonce, certBytes)
self.messages["M1"] = helloPkt.__serialize__()
self.transport.write(helloPkt.__serialize__())
def connection_made(self, transport):
self.log("Connection made at SITH layer on " +
type(self.higherProtocol()).__name__)
self.transport = transport
self.peerAddress = transport.get_extra_info('peername')
super().connection_made(transport)
self.importClientCerts()
self.state = self.STATE_CLIENT_HELLO
self.log(
"Client: Sending Hello message, current state: {!r}, random: {!r}".
format(self.STATE_DESC[self.state], self.random))
self.certBytes = [CipherUtil.serializeCert(c) for c in self.certs]
helloPkt = SITHPacket.makeHelloPacket(self.random, self.certBytes,
self.public_key)
self.messages["M1"] = helloPkt.__serialize__()
self.transport.write(helloPkt.__serialize__()) #send client hello pkt
def data_received(self, data):
self.deserializer.update(data)
for pkt in self.deserializer.nextPackets():
if isinstance(pkt, PlsHello) and self.state == self.STATE_SERVER_HELLO:
# Deserialize certs in packet, attach root cert
peerCerts = [CipherUtil.getCertFromBytes(c) for c in pkt.Certs]
if self.verifyCerts(peerCerts):
self.dbgPrint("Server: PlsHello received!")
self.messages["M1"] = pkt.__serialize__()
self.peerPublicKey = peerCerts[0].public_key()
self.clientNonce = pkt.Nonce
# Make PlsHello and send back
self.serverNonce = self.generateNonce()
# Serialize certs to pack into PlsHello
certBytes = [CipherUtil.serializeCert(c) for c in self.certs]
self.dbgPrint("Server: sending PlsHello back to client... Current state: {!r}, nonce Number: {!r}"
.format(self.STATE_DESC[self.state], self.serverNonce))
helloPkt = PlsHello.makeHelloPacket(self.serverNonce, certBytes)
self.messages["M2"] = helloPkt.__serialize__()
self.transport.write(helloPkt.__serialize__())
self.state = self.STATE_SERVER_KEY_EXCHANGE
else:
self.handleError("Error: certificate verification failure.")
elif isinstance(pkt, PlsKeyExchange) and self.state == self.STATE_SERVER_KEY_EXCHANGE:
if self.serverNonce + 1 == pkt.NoncePlusOne:
self.dbgPrint("Server: received PlsKeyExchange packet from client")
self.messages["M3"] = pkt.__serialize__()
self.clientPreKey = self.privateKey.decrypt(
pkt.PreKey,
padding.OAEP(
mgf=padding.MGF1(algorithm=hashes.SHA1()),
algorithm=hashes.SHA1(),
label=None
)
)
if len(self.clientPreKey) != self.PRE_KEY_LENGTH_BYTES:
self.handleError("Error: Bad client pre-key with length = " + str(len(self.clientPreKey) * 8)
+ " bits, wrong RSA decryption?")
else:
self.dbgPrint("Server: client prekey received: " + self.clientPreKey.hex())
# Make PlsKeyExchange and send back
self.serverPreKey = self.generatePreKey()
self.dbgPrint(
"Server: sending plsKeyExchange packet, prekey: {!r}".format(self.serverPreKey.hex()))
encryptedPreKey = self.peerPublicKey.encrypt(
self.serverPreKey,
padding.OAEP(
mgf=padding.MGF1(algorithm=hashes.SHA1()),
algorithm=hashes.SHA1(),
label=None
)
)
plsKeyExchangePkt = PlsKeyExchange.makePlsKeyExchange(encryptedPreKey, self.clientNonce + 1)
self.messages["M4"] = plsKeyExchangePkt.__serialize__()
self.transport.write(plsKeyExchangePkt.__serialize__())
self.state = self.STATE_SERVER_PLS_HANDSHAKE_DONE
# Enough info to generate keys and initialize ciphers
self.setKeys(self.generateDerivationHash())
self.setEngines()
else:
self.handleError("Error: bad nonce in key exchange.")
elif isinstance(pkt, PlsHandshakeDone) and self.state == self.STATE_SERVER_PLS_HANDSHAKE_DONE:
if self.verifyValidationHash(pkt.ValidationHash):
self.dbgPrint("Server: plsHandshakeDone packet received from client.")
self.dbgPrint(
"Server: sending plsHandshakeDone to client and notifying upper layer connection_made")
hashText = self.generateValidationHash()
handshakeDonePkt = PlsHandshakeDone.makePlsHandshakeDone(hashText)
self.transport.write(handshakeDonePkt.__serialize__())
# Enter transmission
self.state = self.STATE_SERVER_TRANSFER
higherTransport = PLSTransport(self.transport, self)
self.higherProtocol().connection_made(higherTransport)
else:
self.handleError("Error: validation hash verification failure.")
elif isinstance(pkt, PlsData) and self.state == self.STATE_SERVER_TRANSFER:
self.dbgPrint("Server: received application data from client, decrypt and notify upper layer")
if self.verifyPlsData(pkt.Ciphertext, pkt.Mac):
self.dbgPrint("Verification succeeded, sending data to upper layer...")
self.higherProtocol().data_received(self.decrypt(pkt.Ciphertext))
else:
# self.handleError("Error: data verification failure.")
self.dbgPrint("Data MAC verification error, discarded.")
elif isinstance(pkt, PlsClose):
self.dbgPrint("PlsClose received, closing...")
self.transport.close()
else:
self.handleError("Error: wrong packet type " + pkt.DEFINITION_IDENTIFIER + ", current state "
+ self.STATE_DESC[self.state])
def data_received(self, data):
self.deserializer.update(data)
for pkt in self.deserializer.nextPackets():
if isinstance(
pkt, SITHPacket
): # judge if this packet is an instance of RIPPPacket
if (pkt.Type == "HELLO") and (
self.state
== self.STATE_SERVER_HELLO): #receive client hello pkt
# Deserialize certs in packet, attach root cert
self.peerCerts = [
CipherUtil.getCertFromBytes(c) for c in pkt.Certificate
]
if self.verifyCerts(self.peerCerts):
self.log("Server: SithHello received!")
self.messages["M1"] = pkt.__serialize__(
) #turn the client's hello pkt into bytes
self.peerPublicKey = self.peerCerts[0].public_key()
# Serialize certs to pack into SithHello
self.certBytes = [
CipherUtil.serializeCert(c) for c in self.certs
]
self.log(
"Server: sending SithHello back to client... Current state: {!r}, random: {!r}"
.format(self.STATE_DESC[self.state], self.random))
helloPkt = SITHPacket.makeHelloPacket(
self.random, self.certBytes, self.public_key)
self.messages["M2"] = helloPkt.__serialize__(
) #turn the server's hello pkt into bytes
self.transport.write(
helloPkt.__serialize__()
) #send the server hello pkt and enter 'server_key_exchange' stage
self.state = self.STATE_SERVER_KEY_EXCHANGE
#key derivation
self.client_public_key = x25519.X25519PublicKey.from_public_bytes(
pkt.PublicValue
) #load client's public key from bytes
shared_secret = self.private_key.exchange(
self.client_public_key)
hasher = hashes.Hash(hashes.SHA256(),
backend=default_backend())
hasher.update(self.messages["M1"] +
self.messages["M2"])
self.hash_msg = hasher.finalize() #get the hash result
derived_key = HKDF(
algorithm=hashes.SHA256(),
length=32,
salt=None,
info=self.hash_msg,
backend=default_backend()).derive(
shared_secret) #get the derived key
self.iv_dec = derived_key[:12]
self.iv_enc = derived_key[12:24]
self.server_write = derived_key[:16]
self.server_read = derived_key[16:]
self.setEngines()
self.state = self.STATE_SERVER_SITH_HANDSHAKE_DONE
else:
self.log("Error: certificate verification failure.")
self.sendSithClose(1)
elif (pkt.Type == "FINISH") and (
self.state == self.STATE_SERVER_SITH_HANDSHAKE_DONE):
self.log(
"Server: received handshake_finish packet from client")
#verify client's signature
client_public_key = self.peerCerts[0].public_key()
client_signature = pkt.Signature
verify_result = self.verify_signature(
client_public_key, client_signature, self.hash_msg)
if not verify_result:
self.log("Server: wrong signature of client!")
self.log("Server is closing...")
self.sendSithClose(1)
else:
# generate handshake finish pkt
self.cert_private_key = getServerPrivateKey(
) # read private of server's certificate
finishPkt = SITHPacket.makeFinishPacket(
self.messages["M1"], self.messages["M2"],
self.cert_private_key)
self.transport.write(
finishPkt.__serialize__()
) # send the server hello pkt and enter 'server_key_exchange' stage
#enter the data transmission state
self.state = self.STATE_SERVER_TRANSFER
higherTransport = SITHTransport(self.transport, self)
self.higherProtocol().connection_made(higherTransport)
# Enter transmission
higherTransport = SITHTransport(self.transport, self)
self.higherProtocol().connection_made(higherTransport)
elif (pkt.Type
== "DATA") and self.state == self.STATE_SERVER_TRANSFER:
self.log(
"Server: received application data from client, decrypt and notify upper layer"
)
self.log(
"Verification succeeded, sending data to upper layer..."
)
self.higherProtocol().data_received(
self.decrypt(self.iv_dec, pkt.Ciphertext, None))
elif (pkt.Type == "CLOSE"):
self.transport.close()
else:
self.log("Error: wrong packet type " +
pkt.DEFINITION_IDENTIFIER + ", current state " +
self.STATE_DESC[self.state])
self.sendSithClose(1)
else:
self.log("Wrong packet class type: {!r}".format(str(
type(pkt))))
self.sendSithClose(1)
