+from ctypes import *\r
+\r
+CIPHER_ALGORITHMS = ("DES", "DES-EDE3", "BF", "AES-128", "AES-192", "AES-256")\r
+CIPHER_MODES = ("CBC", "CFB", "OFB", "ECB")\r
+\r
+class CipherError(Exception):\r
+ pass\r
+\r
+class CipherType:\r
+\r
+ def __init__(self, libcrypto, cipher_algo, cipher_mode):\r
+ self.libcrypto = libcrypto\r
+ self.cipher_algo = cipher_algo\r
+ self.cipher_mode = cipher_mode\r
+ cipher_name = "-".join([self.cipher_algo, self.cipher_mode])\r
+ self.cipher = self.libcrypto.EVP_get_cipherbyname(cipher_name)\r
+ if self.cipher == 0:\r
+ raise CipherError, "Unknown cipher: %s" % cipher_name\r
+\r
+ def __del__(self):\r
+ pass\r
+\r
+ def algo(self):\r
+ return self.cipher_algo\r
+\r
+ def mode(self):\r
+ return self.cipher_mode\r
+\r
+class Cipher:\r
+\r
+ def __init__(self, libcrypto, cipher_type, key, iv, encrypt=True):\r
+ self.libcrypto = libcrypto\r
+ self._clean_ctx()\r
+ key_ptr = c_char_p(key)\r
+ iv_ptr = c_char_p(iv)\r
+ self.ctx = self.libcrypto.EVP_CIPHER_CTX_new(cipher_type.cipher, None, key_ptr, iv_ptr)\r
+ if self.ctx == 0:\r
+ raise CipherError, "Unable to create cipher context"\r
+ self.encrypt = encrypt\r
+ if encrypt: \r
+ enc = 1\r
+ else: \r
+ enc = 0\r
+ result = self.libcrypto.EVP_CipherInit_ex(self.ctx, cipher_type.cipher, None, key_ptr, iv_ptr, c_int(enc))\r
+ self.cipher_type = cipher_type\r
+ if result == 0:\r
+ self._clean_ctx()\r
+ raise CipherError, "Unable to initialize cipher"\r
+\r
+ def __del__(self):\r
+ self._clean_ctx()\r
+\r
+ def enable_padding(self, padding=True):\r
+ if padding:\r
+ padding_flag = 1\r
+ else:\r
+ padding_flag = 0\r
+ self.libcrypto.EVP_CIPHER_CTX_set_padding(self.ctx, padding_flag)\r
+\r
+ def update(self, data):\r
+ if self.cipher_finalized :\r
+ raise CipherError, "No updates allowed"\r
+ if type(data) != type(""):\r
+ raise TypeError, "A string is expected"\r
+ if len(data) <= 0:\r
+ return ""\r
+ self.data = self.data + data\r
+ \r
+ def finish(self, data=None):\r
+ if data is not None:\r
+ self.update(data)\r
+ return self._finish()\r
+ \r
+ def _finish(self):\r
+ if self.cipher_finalized :\r
+ raise CipherError, "Cipher operation is already completed"\r
+ self.cipher_out = create_string_buffer(len(self.data) + 32)\r
+ result = self.libcrypto.EVP_CipherUpdate(self.ctx, byref(self.cipher_out), byref(self.cipher_out_len), c_char_p(self.data), len(self.data))\r
+ if result == 0:\r
+ self._clean_ctx()\r
+ raise CipherError, "Unable to update cipher"\r
+ self.cipher_finalized = True\r
+ update_data = self.cipher_out.raw[:self.cipher_out_len.value]\r
+ result = self.libcrypto.EVP_CipherFinal_ex(self.ctx, byref(self.cipher_out), byref(self.cipher_out_len))\r
+ if result == 0:\r
+ self._clean_ctx()\r
+ raise CipherError, "Unable to finalize cipher"\r
+ final_data = self.cipher_out.raw[:self.cipher_out_len.value]\r
+ return update_data + final_data\r
+ \r
+ def _clean_ctx(self):\r
+ try:\r
+ if self.ctx is not None:\r
+ self.libcrypto.EVP_CIPHER_CTX_cleanup(self.ctx)\r
+ self.libcrypto.EVP_CIPHER_CTX_free(self.ctx)\r
+ del(self.ctx)\r
+ except AttributeError:\r
+ pass\r
+ self.cipher_out = None\r
+ self.cipher_out_len = c_long(0)\r
+ self.data = ""\r
+ self.cipher_finalized = False
\ No newline at end of file