Python 3 implementation of PBEWITHMD5andDES Java

PBEWITHMD5andDES_cipher.py

from Crypto.Hash import MD5
from Crypto.Cipher import DES
import base64
import random
import sys


def randomBytes(n):
    return bytearray(random.getrandbits(8) for i in range(n))


def jdkPBE_cipher_PBEWITHMD5andDES(password, plaintext):
    bs = 8
    _iterations = 1000

    data = bytes(plaintext.encode())
    padding = bs - (len(data) % bs)
    data += bytes((chr(padding) * padding).encode())

    salt = randomBytes(bs)

    hasher = MD5.new()
    hasher.update(bytearray(password.encode()))
    hasher.update(salt)
    result = hasher.digest()

    for i in range(1, _iterations):
        hasher = MD5.new()
        hasher.update(result)
        result = hasher.digest()

    encoder = DES.new(result[:bs], DES.MODE_CBC, result[bs:bs*2])
    encrypted = encoder.encrypt(data)
    return salt+encrypted


def jdkPBE_decipher_PBEWITHMD5andDES(password, data_to_decrypt):
    bs = 8
    _iterations = 1000
    salt = data_to_decrypt[:bs]
    data = data_to_decrypt[bs:]

    hasher = MD5.new()
    hasher.update(bytearray(password.encode()))
    hasher.update(bytearray(salt))
    result = hasher.digest()

    for i in range(1, _iterations):
        hasher = MD5.new()
        hasher.update(result)
        result = hasher.digest()

    encoder = DES.new(result[:bs], DES.MODE_CBC, result[bs:bs*2])
    decrypted = encoder.decrypt(bytes(data))

    length = len(decrypted)
    unpadding = int(decrypted[length-1])

    if length - unpadding > 0:
        return decrypted[:(length - unpadding)].decode()
    else:
        return decrypted.decode()


def jdkPBE_decipher(ciphername, password, src):
    if ciphername == "PBEWITHMD5andDES":
        return jdkPBE_decipher_PBEWITHMD5andDES(password, base64.b64decode(src))
    else:
        raise Exception('unable to decode with {}'.format(ciphername))


def jdkPBE_cipher(ciphername, password, src):
    if ciphername == "PBEWITHMD5andDES":
        return base64.b64encode(
                jdkPBE_cipher_PBEWITHMD5andDES(password, src)).decode()
    else:
        raise Exception('unable to encode with {}'.format(ciphername))


if "__main__" == __name__:

    if len(sys.argv) == 2 and sys.argv[1] == 't':
        _password = 'strangepassword'
        _cypherdata = 'ZJCmwXlI2Uybx+GwocCD5GxmScwLHDWKM9IO7PXkX4' \
                      '1lAhkN3wAWV/8q9jeV7K0dFKo4/NWphE37YiLga2RT' \
                      'uWlWh5Jvxv6s'
        _plaintext_to_encrypt = 'João Alves was here'

        _encrypted = jdkPBE_cipher('PBEWITHMD5andDES',
                                   _password,
                                   _plaintext_to_encrypt)
        print('Encrypting [{}] with password [{}] '
              'using PBEWITHMD5andDES -> [{}]'
              .format(_plaintext_to_encrypt, _password, _encrypted))

        _encrypted2 = jdkPBE_cipher('PBEWITHMD5andDES',
                                    _password,
                                    _plaintext_to_encrypt)
        _decrypted2 = jdkPBE_decipher('PBEWITHMD5andDES',
                                      _password,
                                      _encrypted2)
        print('Encrypting and Decrypting the [{}] with password [{}] '
              'using PBEWITHMD5andDES -> [{}]'
              .format(_plaintext_to_encrypt, _password, _decrypted2))

        _decrypt_cypher = jdkPBE_decipher('PBEWITHMD5andDES',
                                          _password,
                                          _cypherdata)
        print('Decrypting [{}] with password [{}] '
              'using PBEWITHMD5andDES -> [{}]'
              .format(_cypherdata, _password, _decrypt_cypher))
        exit(0)

    if len(sys.argv) < 5:
        print('''Args: operation ciphername password msg
Ex. to encrypt: e PBEWITHMD5andDES simplepass "Test"
Ex. to decrypt: d PBEWITHMD5andDES simplepass pkRuP5Q6b6ttjEdSF0IBbw==
        ''')
        exit(1)

    operation = sys.argv[1]
    ciphername = sys.argv[2]
    password = sys.argv[3]
    src = sys.argv[4]

    if operation == "e":
        msg = jdkPBE_cipher(ciphername, password, src)
        print(msg)
    if operation == "d":
        msg = jdkPBE_decipher(ciphername, password, src)
        print(msg)

Can you provide the code that generates that error? Regards, João

…

On Mon, 29 Nov 2021 at 11:33, Esteban Sorribas ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ Hi Joao, Thanks for the GIST, I have a question. When I run the class trying to decode data I have this message: "Data must be padded to 8 byte boundary in CBC mode" Do you what is causing this Exception? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://gist.github.com/505e653fd1c7358ad2c540e25e1ee80a#gistcomment-3977550>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAFCKSEMPMER7GYHONXSL73UONQKJANCNFSM5I64SAFA> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>.

-- <https://about.me/jpralves?promo=email_sig&utm_source=product&utm_medium=email_sig&utm_campaign=edit_panel&utm_content=thumb> João Alves about.me/jpralves <https://about.me/jpralves?promo=email_sig&utm_source=product&utm_medium=email_sig&utm_campaign=edit_panel&utm_content=thumb>