88 lines
2.3 KiB
Python
Executable File
88 lines
2.3 KiB
Python
Executable File
#!/usr/bin/env python3
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import hashlib
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from Crypto.Cipher import AES
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from Crypto.Util import Padding
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from Crypto.Hash import HMAC, SHA256
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import sys
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from getpass import getpass
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from docopt import docopt
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from os import listdir
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IV_LENGTH = 16
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NONCE_LENGTH = 16
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MAC_LENGTH = 16
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iv = bytearray(IV_LENGTH)
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FORMAT_STRING = 'window.Signal.Backup.exportToDirectory(\'{0}\', {{\'key\':new Uint8Array({1})}});'
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USAGE_STRING = """
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Usage:
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signalDesktopDecrypt generate --path <path>
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signalDesktopDecrypt decrypt --path <path>
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"""
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def decrypt(cipherkey, ciphertext):
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cipher = AES.new(cipherkey, AES.MODE_CBC, iv)
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return Padding.unpad(cipher.decrypt(ciphertext), AES.block_size)
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def generate_cipherkey(key, nonce):
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h = HMAC.new(key, digestmod=SHA256)
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h.update(nonce)
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return h.digest()
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def generate_key(password):
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m = hashlib.sha256()
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m.update(password)
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return m.digest()
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def extract_info(filepath):
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data = ''
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try:
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with open(filepath, 'rb') as fh:
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data = fh.read()
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except FileNotFoundError:
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print(filepath + ' was not found, please check --path argument')
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sys.exit(1)
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# extract none
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nonce = data[:NONCE_LENGTH]
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# extract ciphertext
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ciphertext = data[NONCE_LENGTH:-MAC_LENGTH]
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return nonce, ciphertext
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def main():
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params = docopt(USAGE_STRING)
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if params['generate']:
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# ask for password
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password = getpass()
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key = generate_key(password.encode('utf-8'))
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# generate string to be pasted in Signal-Desktop
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print('Use ctrl+i to open the developer tools in the signal desktop app, switch to console and paste the following text:\n')
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print(FORMAT_STRING.format(params['<path>'], [elem for elem in key]))
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return
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elif params['decrypt']:
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# ask for password
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password = getpass()
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key = generate_key(password.encode('utf-8'))
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# extract messages.zip
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nonce, ciphertext = extract_info(params['<path>'] + '/messages.zip')
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cipherkey = generate_cipherkey(key, nonce)
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with open(params['<path>'] + '/messages.zip', 'wb') as fh:
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fh.write(decrypt(cipherkey, ciphertext))
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# extract attachments
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for filename in listdir(params['<path>'] + '/attachments/'):
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nonce, ciphertext = extract_info(params['<path>'] + '/attachments/' + filename)
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cipherkey = generate_cipherkey(key, nonce)
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with open(params['<path>'] + '/attachments/' + filename, 'wb') as fh:
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fh.write(decrypt(cipherkey, ciphertext))
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if __name__ == '__main__':
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main()
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