def Test_Verify_Hmac():
message = urandom(1212)
sharedHkey = urandom(32)
hmac_Calculated = common.get_HMAC(message,sharedHkey)
print "hmac_Calculated = %s" % hmac_Calculated
if common.Verify_HMAC(message, hmac_Calculated, sharedHkey):
print "HMAC verification : success"
else:
print "HMAC verification : FAILURE"
def Ask_Server_For_List(username):
nonceServer = common.Increment_Nonce(clientDataTable[1][6])
clearText = ''.join([nonceServer, username])
cipherText, iv = common.Symmetric_Encrypt(clearText, clientDataTable[1][4])
hmacInputData = ''.join([iv, cipherText])
hmac = common.get_HMAC(hmacInputData, clientDataTable[1][5])
sendData = ''.join([common.Get_Message_ID("client_to_server_list_update"), hmac, hmacInputData])
sockClient.send(sendData)
clientDataTable[1][6] = nonceServer
return
if recvdUsername != currentUserDataList[0]:
print "Username doesn't match the client IP / Port combo"
continue
# HMAC, nonce and username is verified at this point, next we prepare the response
response_nonce = common.Increment_Nonce(recvdNonce)
userListMessage = ""
for i in range(0, len(authed_users)):
userListMessage = ''.join([userListMessage, chr(len(authed_users[i][0])), authed_users[i][0]])
# using chr(0) as a delimiter between user list and number of users
userListMessageWithLength = ''.join([userListMessage, chr(0), str(len(authed_users))])
# print userListMessage
response_plaintext = ''.join([response_nonce, userListMessageWithLength])
# print response_plaintext
response_ciphertext, response_iv = common.Symmetric_Encrypt(response_plaintext, shared_aes)
response_hmacInput = ''.join([response_iv, response_ciphertext])
response_hmac = common.get_HMAC(response_hmacInput, shared_hkey)
response_message_id = common.Get_Message_ID("server_to_client_user_list")
sendData = ''.join([response_message_id, response_hmac, response_hmacInput])
sock.send(sendData)
# updating Nonce to response_Nonce in authed_users
authed_users[authdUsersListIndex][6] = response_nonce
print "sent user list to username = %s" % recvdUsername
continue
##################### Handles the support for client to client communication ##################
# Handles the Client1 request to server to initiate communication with client2 and sends a headsup to Client2
if client_message_id_name == "client1_request_to_server_for_client2":
A1UserDataList, A1userFound, A1authdUsersListIndex = Get_User_Data_with_ip_port(client_ip, client_port)
if A1userFound == False:
print "Could not find source client IP or Port in the authd users list"
continue
