182 lines
6.0 KiB
Python
182 lines
6.0 KiB
Python
# Joint copyright of Josh Conway and discord user:winter_soldier#1984
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# License is GPL3 (Gnu public license version 3)
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import sys
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import os
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import time
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import argparse
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import base64
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import socket
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import zmq
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from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
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from cryptography.hazmat.backends import default_backend
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# SDR output example data: ffffffffb45463dab971aa8c6308000078aacf76587a5a4cf4a20e2c1d0349ab3f72
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# Use default key. Result should be: b'\x08\x01\x12\x0eTestingCLU1234'
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##### START FUNCTIONS BLOCK #####
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# Takes in a string encoded as hex, and emits them as a bytes encoded of the same hex representation
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def hexStringToBinary(hexString):
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binString = bytes.fromhex(hexString)
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return binString
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def bytesToHexString(byteString):
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hexString = byteString.hex()
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return hexString
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##### END FUNCTIONS BLOCK #####
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##### START PARSE COMMANDLINE INPUT #####
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parser = argparse.ArgumentParser(description='Process incoming command parmeters')
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parser.add_argument('-i', '--input', action='store', dest='input', help='SDR capture of the full Meshtastic LoRa string')
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parser.add_argument('-k', '--key', action='store',dest='key', help='AES key override in Base64')
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parser.add_argument('-n', '--net', action='store',dest='net', help='Network TCP in ip or DNS. ZeroMQ protocol.')
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parser.add_argument('-p', '--port', action='store',dest='port', help='Network port')
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args = parser.parse_args()
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##### END PARSE COMMANDLINE INPUT #####
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##### START AES KEY ASSIGNMENT BLOCK #####
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def parseAESKey(aesKey):
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# We look if there's a "NOKEY" declaration, a key provided, or an absence of key. We do the right thing depending on each choice.
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# The "NOKEY" is basically ham mode. You're forbidden from using encryption.
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# If you dont provide a key, we use the default one. We try to make it easy on our users!
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# Note this format is in Base64
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try:
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if args.key == "0" or args.key == "NOKEY" or args.key == "nokey" or args.key == "NONE" or args.key == "none" or args.key == "HAM" or args.key == "ham":
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meshtasticFullKeyBase64 = "AAAAAAAAAAAAAAAAAAAAAA=="
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elif ( len(args.key) > 0 ):
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meshtasticFullKeyBase64 = args.key
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except:
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meshtasticFullKeyBase64 = "1PG7OiApB1nwvP+rz05pAQ=="
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# Validate the key is 128bit/32byte or 256bit/64byte long. Fail if not.
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aesKeyLength = len(base64.b64decode(meshtasticFullKeyBase64).hex())
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if (aesKeyLength == 32 or aesKeyLength == 64):
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pass
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else:
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print("The included AES key appears to be invalid. The key length is" , aesKeyLength , "and is not the key length of 128 or 256 bits.")
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sys.exit()
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# Convert the key FROM Base64 TO hexadecimal.
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return base64.b64decode(meshtasticFullKeyBase64.encode('ascii'))
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##### END AES KEY ASSIGNMENT BLOCK #####
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##### START DATA EXTRACTION BLOCK #####
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def dataExtractor(data):
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# Now we split the data into the appropriate meshtastic packet structure using https://meshtastic.org/docs/overview/mesh-algo/
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# NOTE: The data coming out of GnuRadio is MSB or big endian. We have to reverse byte order after this step.
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# destination : 4 bytes
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# sender : 4 bytes
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# packetID : 4 bytes
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# flags : 1 byte
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# channelHash : 1 byte
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# reserved : 2 bytes
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# data : 0-237 bytes
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meshPacketHex = {
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'dest' : hexStringToBinary(data[0:8]),
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'sender' : hexStringToBinary(data[8:16]),
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'packetID' : hexStringToBinary(data[16:24]),
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'flags' : hexStringToBinary(data[24:26]),
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'channelHash' : hexStringToBinary(data[26:28]),
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'reserved' : hexStringToBinary(data[28:32]),
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'data' : hexStringToBinary(data[32:len(data)])
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}
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return meshPacketHex
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##### END DATA EXTRACTION BLOCK #####
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##### START DECRYPTION PROCESS #####
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def dataDecryptor(meshPacketHex, aesKey):
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# Build the nonce. This is (packetID)+(00000000)+(sender)+(00000000) for a total of 128bit
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# Even though sender is a 32 bit number, internally its used as a 64 bit number.
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# Needs to be a bytes array for AES function.
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aesNonce = meshPacketHex['packetID'] + b'\x00\x00\x00\x00' + meshPacketHex['sender'] + b'\x00\x00\x00\x00'
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# print("Nonce binary is:", aesNonce)
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# print("Nonce length is:", len(aesNonce) )
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# Initialize the cipher
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cipher = Cipher(algorithms.AES(meshtasticFullKeyHex), modes.CTR(aesNonce), backend=default_backend())
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decryptor = cipher.decryptor()
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# Do the decryption. Note, that this cipher is reversible, so running the cipher on encrypted gives decrypted, and running the cipher on decrypted gives encrypted.
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decryptedOutput = decryptor.update(meshPacketHex['data']) + decryptor.finalize()
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return decryptedOutput
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##### END DECRYPTION PROCESS #####
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##### START OPTIONAL NETWORK PROCESS #####
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def networkParse(ipAddr, port, aesKey):
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context = zmq.Context()
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socket = context.socket(zmq.SUB)
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socket.connect("tcp://" + ipAddr + ":" + port) # connect, not bind, the PUB will bind, only 1 can bind
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socket.setsockopt(zmq.SUBSCRIBE, b'') # subscribe to topic of all (needed or else it won't work)
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while True:
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if socket.poll(10) != 0: # check if there is a message on the socket
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msg = socket.recv() # grab the message
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extractedData = dataExtractor(msg.hex())
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decryptedData = dataDecryptor(extractedData, aesKey)
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print(decryptedData)
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else:
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time.sleep(0.1) # wait 100ms and try again
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##### START OPTIONAL NETWORK PROCESS #####
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if __name__ == "__main__":
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meshtasticFullKeyHex = parseAESKey(args.key)
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# Network branch. Doesnt exit, so we need IP Port and AES key
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try:
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print("do we have ip and port?")
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if len(args.net) > 0 and len(args.port) > 0:
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print(args.net, args.port)
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networkParse(args.net, args.port, meshtasticFullKeyHex)
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except:
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# If we get a payload on commandline, decrypt and exit.
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meshPacketHex = dataExtractor(args.input)
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decryptedData = dataDecryptor(meshPacketHex, meshtasticFullKeyHex)
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print(decryptedData)
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