pycrypto->cryptography

crypt.py

import os
import six
import uuid

from Crypto.Cipher import AES
from cryptography.hazmat import backends
from cryptography.hazmat.primitives import ciphers
from cryptography.hazmat.primitives.ciphers import algorithms
from cryptography.hazmat.primitives.ciphers import modes
from cryptography.hazmat.primitives import padding


def _pycrypto_encrypt(key, data, iv):
    cipher = AES.new(key, AES.MODE_CBC, iv)
    padding = 16 - len(data) % 16
    padded_data = data + six.int2byte(padding) * padding
    return iv + cipher.encrypt(padded_data)


def _pycrypto_decrypt(key, data):
    cipher = AES.new(key, AES.MODE_CBC, data[:16])
    result = cipher.decrypt(data[16:])
    return result[:-1 * six.byte2int([result[-1]])]


def _cryptography_encrypt(key, data, iv):
    cipher = ciphers.Cipher(
        algorithms.AES(key),
        modes.CBC(iv),
        backend=backends.default_backend())
    padder = padding.PKCS7(256).padder()
    padded_data = padder.update(data) + padder.finalize()
    encryptor = cipher.encryptor()
    return iv + encryptor.update(padded_data) + encryptor.finalize()


def _cryptography_decrypt(key, data):
    cipher = ciphers.Cipher(
        algorithms.AES(key),
        modes.CBC(data[:16]),
        backend=backends.default_backend())
    decryptor = cipher.decryptor()
    result = decryptor.update(data[16:]) + decryptor.finalize()
    unpadder = padding.PKCS7(256).unpadder()
    unpadded_data = unpadder.update(result) + unpadder.finalize()
    return unpadded_data


def main():
    message = b'[Eat my shorts!]'
    key = uuid.uuid4().hex
    iv = os.urandom(16)

    enc_pycrypto = _pycrypto_encrypt(key, message, iv)
    print 'pycrypto ciphertext: %r' % enc_pycrypto
    enc_cryptography = _cryptography_encrypt(key, message, iv)
    print 'cryptography ciphertext: %r' % enc_cryptography

    dec_pycrpyto_with_pycrypto = _pycrypto_decrypt(key, enc_pycrypto)
    print 'decrypt pycrypto with pycrypto %r' % dec_pycrpyto_with_pycrypto
    dec_pycrpyto_with_cryptography = _cryptography_decrypt(key, enc_pycrypto)
    print 'decrypt pycrypto with cryptography %r' % dec_pycrpyto_with_cryptography
    assert dec_pycrpyto_with_pycrypto == dec_pycrpyto_with_cryptography

    dec_crypto_with_pycrypto = _pycrypto_decrypt(key, enc_cryptography)
    print 'decrypt cryptography with pycrypto %r' % dec_crypto_with_pycrypto
    dec_crypto_with_cryptography = _cryptography_decrypt(key, enc_cryptography)
    print 'decrypt cryptography with cryptography %r' % dec_crypto_with_cryptography
    assert dec_crypto_with_pycrypto == dec_crypto_with_cryptography


if __name__ == '__main__':
    main()

results

pycrypto ciphertext: '\x8e\x14\xdd\x85\x90\xb1\x95WB\xce#d.\x1c\xca\x94/KzY\xeb\x01\xafF\x80lI\xf0\xe1\xb7t\x00\xb8\xf9\xaeW!\xcd\xfa\xdfG_\x8e\x96\xec\x03m\xf7'
cryptography ciphertext: '\x8e\x14\xdd\x85\x90\xb1\x95WB\xce#d.\x1c\xca\x94/KzY\xeb\x01\xafF\x80lI\xf0\xe1\xb7t\x00\xb8\xf9\xaeW!\xcd\xfa\xdfG_\x8e\x96\xec\x03m\xf7'
decrypt pycrypto with pycrypto '[Eat my shorts!]'
decrypt pycrypto with cryptography '[Eat my shorts!]'
decrypt cryptography with pycrypto '[Eat my shorts!]'
decrypt cryptography with cryptography '[Eat my shorts!]'