Personal Computer World 2009 February/PCWFEB09.iso/Software/Resources/Chat & Communication/Digsby build 37/digsby_setup.exe/lib/util/cryptography.pyo

Python Compiled Bytecode | 2008-10-13 | 6KB | 215 lines

# Source Generated with Decompyle++
# File: in.pyo (Python 2.5)

from hashlib import sha1 as _DefaultHash

def _key_prep(key, hash = _DefaultHash, length = 16):
    return hash(key).digest()[:length]


def pad(s, sz, padchar = '\x00'):
    extralen = (sz - len(s) % sz) % sz
    return s + extralen * padchar


def unpad(s, padchar = '\x00'):
    return s.rstrip(padchar)


def _encrypt(key, plain, padchar = '\x00'):
    Cipher = AES
    import Crypto.Cipher
    cipher = Cipher.new(key)
    plain = pad(plain, cipher.block_size, padchar)
    return cipher.encrypt(plain)


def _decrypt(key, crypt, padchar = '\x00'):
    Cipher = AES
    import Crypto.Cipher
    cipher = Cipher.new(key)
    return cipher.decrypt(crypt).rstrip(padchar)


def cipher_functions(key, padchar = '\x00'):

    def _encrypt(plain):
        return encrypt(key, plain, padchar = padchar)


    def _decrypt(crypt):
        return decrypt(key, crypt, padchar = padchar)

    return (_encrypt, _decrypt)


def hash(s, raw = True, Hash = _DefaultHash):
    if raw:

        digest = lambda x: x.digest()
    else:

        digest = lambda x: x.hexdigest()
    return digest(Hash(s))


def encrypt(key, plain, iv = None, padchar = '\x00'):
    if iv is None:
        iv = '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

    mode = 2
    aes = OpenSSL_AES(key, mode, iv)
    plain = pad(plain, aes.block_size, padchar)
    return aes.encrypt(plain)


def decrypt(key, crypt, iv = None, padchar = '\x00'):
    if iv is None:
        iv = '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

    mode = 2
    aes = OpenSSL_AES(key, mode, iv)
    return unpad(aes.decrypt(crypt), padchar)


try:
    from M2Crypto import m2
except ImportError:
    has_AES = False
    has_DES3 = False

has_AES = True
has_DES3 = True

class OpenSSL_AES(object):

    def __init__(self, key, mode, IV):
        if len(key) not in (16, 24, 32):
            raise AssertionError()

        if mode != 2:
            raise AssertionError()

        if len(IV) != 16:
            raise AssertionError()

        self.isBlockCipher = True
        self.block_size = 16
        self.implementation = 'openssl'
        if len(key) == 16:
            self.name = 'aes128'
        elif len(key) == 24:
            self.name = 'aes192'
        elif len(key) == 32:
            self.name = 'aes256'
        else:
            raise AssertionError()
        self.key = key
        self.IV = IV


    def _createContext(self, encrypt):
        context = m2.cipher_ctx_new()
        if len(self.key) == 16:
            cipherType = m2.aes_128_ecb()

        if len(self.key) == 24:
            cipherType = m2.aes_192_ecb()

        if len(self.key) == 32:
            cipherType = m2.aes_256_ecb()

        m2.cipher_init(context, cipherType, self.key, self.IV, encrypt)
        return context


    def encrypt(self, plaintext):
        if not plaintext:
            return ''

        context = self._createContext(1)
        ciphertext = m2.cipher_update(context, plaintext)
        m2.cipher_ctx_free(context)
        self.IV = ciphertext[-(self.block_size):]
        return ciphertext


    def decrypt(self, ciphertext):
        if not ciphertext:
            return ''

        context = self._createContext(0)
        plaintext = m2.cipher_update(context, ciphertext + '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
        plaintext = plaintext[:len(ciphertext)]
        m2.cipher_ctx_free(context)
        self.IV = ciphertext[-(self.block_size):]
        return plaintext


AES = OpenSSL_AES

class OpenSSL_TripleDES(object):

    def __init__(self, key, mode, IV):
        if len(key) != 24:
            raise ValueError()

        if mode != 2:
            raise ValueError()

        if len(IV) != 8:
            raise ValueError()

        self.isBlockCipher = True
        self.block_size = 8
        self.implementation = 'openssl'
        self.name = '3des'
        self.key = key
        self.IV = IV


    def _createContext(self, encrypt):
        context = m2.cipher_ctx_new()
        cipherType = m2.des_ede3_cbc()
        m2.cipher_init(context, cipherType, self.key, self.IV, encrypt)
        return context


    def encrypt(self, plaintext):
        if not plaintext:
            return ''

        context = self._createContext(1)
        ciphertext = m2.cipher_update(context, plaintext)
        m2.cipher_ctx_free(context)
        self.IV = ciphertext[-(self.block_size):]
        return ciphertext


    def decrypt(self, ciphertext):
        if not ciphertext:
            return ''

        context = self._createContext(0)
        plaintext = m2.cipher_update(context, ciphertext + '\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
        plaintext = plaintext[:len(ciphertext)]
        m2.cipher_ctx_free(context)
        self.IV = ciphertext[-(self.block_size):]
        return plaintext


DES3 = OpenSSL_TripleDES

def _main():
    key = _key_prep('this is my key')
    plaintext = 'abcd' * 80
    old = encrypt(key, plaintext)
    new = _encrypt(key, plaintext)
    print (old, new), old == new
    print (decrypt(key, new), _decrypt(key, old))
    print 'yay'

if __name__ == '__main__':
    _main()