# The next line generates the round keys for simplified AES
simplified_AES.keyExp(SymmKey)
challenge = generateNonce()
# Add code to ensure that the challenge can always be encrypted
# correctly with RSA.
state['nonce'] = challenge
msg = SessionKeyResp(RSAcrypt(challenge, priv_exp, modulus))
s.sendall(bytes(msg, 'utf-8'))
status = 1
strSessionKeyResp = "130 "
if strSessionKeyResp in msg and status == -2:
RcvdStr = msg.split(' ')
encryptedChallenge = int(RcvdStr[1])
# The next line runs AES decryption to retrieve the key.
decryptedChallenge = simplified_AES.decrypt(encryptedChallenge)
msg = nonceVerification(challenge, decryptedChallenge)
s.sendall(bytes(msg,'utf-8'))
status = 0 # To terminate loop at server.
# status can only be -2 if none of the other branches were followed
if status==-2:
print("Incoming message was not processed. \r\n Terminating")
status = -1
return status
def main():
"""Driver function for the project"""
args = sys.argv
if len(args) != 2:
def processMsgs(s, msg, state):
"""This function processes messages that are read through the socket. It
returns a status, which is an integer indicating whether the operation
was successful"""
status = -2
modulus = int(state['modulus']) # modulus = modulus for RSA
pub_exp = int(state['pub_exp']) # pub_exp = public exponent
priv_exp = int(state['priv_exp']) # priv_exp = secret key
challenge = int(state['nonce']) # challenge = nonce sent to client
SymmKey = int(state['SymmetricKey']) # SymmKey = shared symmetric key
rolls = int(state['Rolls']) # rolls = number of dice rolls
dice = state['Dice'] # Dice = values of dice
dice = list(map(int, dice)) # Converting dice values to ints
strTest = "100 Hello"
if strTest in msg and status == -2:
print("Message received: " + msg)
msg = clientHelloResp(modulus, pub_exp)
s.sendall(bytes(msg, 'utf-8'))
status = 1
print("Message sent: ", msg)
strSessionKey = "110 SessionKey"
if strSessionKey in msg and status == -2:
print("Message received: " + msg)
RcvdStr = msg.split(' ')
encSymmKey = int(RcvdStr[2])
SymmKey = RSAdecrypt(encSymmKey, priv_exp,
modulus) ## Add code to decrypt symmetric key
state['SymmetricKey'] = SymmKey
# The next line generates the round keys for simplified AES
simplified_AES.keyExp(SymmKey)
challenge = generateNonce()
# Add code to ensure that the challenge can always be encrypted
# correctly with RSA.
while (challenge > modulus
): # While loops executes if challenge is more than modulus.
temp = generateNonce() # Generating a new nonce.
challenge = temp # Setting challenge to the newly generated nonce.
#Do this
state['nonce'] = challenge
msg = SessionKeyResp(RSAdecrypt(challenge, priv_exp, modulus))
s.sendall(bytes(msg, 'utf-8'))
status = 1
print("Decrypted Symmetric Key: ", SymmKey)
print("d: ", priv_exp)
print("n: ", modulus)
print("Challenge: ", challenge)
print("Message sent: ", msg)
strSessionKeyResp = "130 Transformed Nonce"
if strSessionKeyResp in msg and status == -2:
print("Message received: " + msg)
RcvdStr = msg[22:]
encryptedChallenge = int(RcvdStr)
# The next line runs AES decryption to retrieve the key.
decryptedChallenge = simplified_AES.decrypt(encryptedChallenge)
msg = nonceVerification(challenge, decryptedChallenge)
s.sendall(bytes(msg, 'utf-8'))
status = 1
strDiceRollResp = "200 Roll Dice"
if strDiceRollResp in msg and status == -2:
print("Message received: " + msg)
RcvdStr = msg[14:]
if (len(RcvdStr) > 0):
RcvdStrParams = RcvdStr.split(',')
toRoll = list(map(int, RcvdStrParams))
rollDice(dice, toRoll)
else:
rollDice(dice)
if (rolls < 3):
status = 1
else:
status = 0
rolls += 1
state['Dice'] = dice
state['Rolls'] = rolls
msg = RollDiceACK(dice)
s.sendall(bytes(msg, 'utf-8'))
# status can only be -2 if none of the other branches were followed
if status == -2:
print("Incoming message was not processed. \r\n Terminating")
status = -1
return status
def handleConnection(p, q, n, e, d, conn, addr):
# Protocol
strHello = "100 Hello"
strHelloResp = "105 Hello"
strSessionKey = "112 SessionKey"
strSessionKeyResp = "113 Nonce"
strNonceResp = "130"
print("Waiting to receive hello message from client...")
buff = conn.recv(1024).decode("utf-8")
if not buff:
handleRemoteHostDisappear(conn)
return
if buff.find(strHello) >= 0:
print("Received hello message.")
msg = clientHelloResp(n, e)
print("Pending response:")
print("\t" + str(msg))
print("Sending...")
try:
conn.sendall(bytes(msg, "utf-8"))
except socket.error:
print("")
print("Error sending data to client")
sys.exit(1)
print("Response sent.")
print("")
else:
handleProtocolError(buff, conn)
return
print("Waiting to receive public key from client...")
buff = conn.recv(1024).decode("utf-8")
if not buff:
handleRemoteHostDisappear(conn)
return
if buff.find(
"110 PB"
) >= 0: # I'll pretend that this will somehow be useful. Hmmm...
print("Public key received.")
print("Parsing response...")
data = buff.split(" ")
n_remote_host = int(data[2]) # Modulus for public key encryption
e_remote_host = int(data[3]) # Exponent for public key encryption
print("Client's public key: (" + str(n_remote_host) + ", " +
str(e_remote_host) + ")")
print("Sending receipt ack...")
try:
conn.sendall(bytes("111 ACK PB", "utf-8"))
except socket.error:
print("")
print("Error sending data to client")
sys.exit(1)
print("Receipt ack sent.")
print("")
else:
handleProtocolError(buff, conn)
return
print("Waiting to retrieve session key from client...")
buff = conn.recv(1024).decode("utf-8")
if not buff:
handleRemoteHostDisappear(conn)
return
if buff.find(strSessionKey) >= 0:
print("Received session key.")
encryptedSymmKey = int(buff.split(" ")[2])
print("Encrypted session key: " + str(encryptedSymmKey))
print("Decrypting session key...")
SymmKey = RSAdecrypt(encryptedSymmKey, d, n)
print("Decrypted session key: " + str(SymmKey))
print("Creating challenge....")
# The next line generates the round keys for simplified AES
simplified_AES.keyExp(SymmKey)
challenge = generateNonce()
while challenge >= n: # Nonce sometimes exceeds n and gives me 400 Error >:(
challenge = generateNonce()
print("Encrypted challenge: " + str(challenge))
print("Decrypting challenge/creating nonce...")
msg = SessionKeyResp(RSAdecrypt(challenge, d, n))
print("Pending message with challenge for client:")
print("\t" + str(msg))
print("Sending...")
try:
conn.sendall(bytes(msg, "utf-8"))
except socket.error:
print("")
print("Error sending data to client")
sys.exit(1)
print("Challenge sent.")
print("")
else:
handleProtocolError(buff, conn)
return
print("Waiting on challenge response from client...")
buff = conn.recv(1024).decode("utf-8")
if not buff:
handleRemoteHostDisappear(conn)
return
if buff.find(strNonceResp) >= 0:
print("Received challenge response.")
encryptedChallenge = int(buff.split(" ")[1])
print("Encrypted challenge response: " + str(encryptedChallenge))
print("Decrypting...")
# The next line runs AES decryption to retrieve the key.
decryptedChallenge = simplified_AES.decrypt(encryptedChallenge)
print("Decrypted challenge response: " + str(decryptedChallenge))
msg = nonceVerification(challenge, decryptedChallenge)
print("Pending message to client:")
print("\t" + str(msg))
print("Sending...")
try:
conn.sendall(bytes(msg, "utf-8"))
except socket.error:
print("")
print("Error sending data to client")
sys.exit(1)
print("Message sent.")
print("")
else:
handleProtocolError(buff, conn)
return
print("Closing connection...")
conn.close()
print("Connection closed.")
print("")
splitd = data.split(" ")
encr_symm_key = int(splitd[2])
#print("encrypted symm key ",encr_symm_key) //test
symmKey = RSAdecrypt(encr_symm_key,d,n)# Make appropriate function call to decrypt the symmetric key
#print(symmKey," symm")
# The next line generates the round keys for simplified AES
simplified_AES.keyExp(symmKey)
challenge = generateNonce()
while challenge>n:
challenge = generateNonce()
print("the challenge is ",challenge)
temp = RSAdecrypt(challenge, d, n)
#print ("RSAed nonce",temp) //test
msg = SessionKeyResp(temp)
conn.sendall(bytes(msg,'utf-8'))
data = conn.recv(1024).decode('utf-8')
if data and data.find(strNonceResp) >= 0: # Add code to parse the received string and extract the nonce
splitd = data.split(" ")
encryptedChallenge = int(splitd[1])
#print("plaintext recieved",encryptedChallenge) //test
# The next line runs AES decryption to retrieve the key.
decryptedChallenge = simplified_AES.decrypt(encryptedChallenge)
#print("plaintext decrypted", type(decryptedChallenge)) //test
msg = nonceVerification(challenge,decryptedChallenge)# Make function call to compare the nonce sent with that received
conn.sendall(bytes(msg,'utf-8'))
conn.close()
def DHdecrypt(C, symmetricKey, priv, p):
simplified_AES.keyExp(symmetricKey)
plaintext = simplified_AES.decrypt(C)
return plaintext
def decryptMsg(C, symmetricKey, priv, p):
"""Decrypt a cipher C given parameters above"""
simplified_AES.keyExp(symmetricKey)
plaintext = simplified_AES.decrypt(C)
return plaintext
