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Simple Python example of AES in CBC mode.
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| from hashlib import md5 | |
| from base64 import b64decode | |
| from base64 import b64encode | |
| from Crypto import Random | |
| from Crypto.Cipher import AES | |
| # Padding for the input string --not | |
| # related to encryption itself. | |
| BLOCK_SIZE = 16 # Bytes | |
| pad = lambda s: s + (BLOCK_SIZE - len(s) % BLOCK_SIZE) * \ | |
| chr(BLOCK_SIZE - len(s) % BLOCK_SIZE) | |
| unpad = lambda s: s[:-ord(s[len(s) - 1:])] | |
| class AESCipher: | |
| """ | |
| Usage: | |
| c = AESCipher('password').encrypt('message') | |
| m = AESCipher('password').decrypt(c) | |
| Tested under Python 3 and PyCrypto 2.6.1. | |
| """ | |
| def __init__(self, key): | |
| self.key = md5(key.encode('utf8')).hexdigest() | |
| def encrypt(self, raw): | |
| raw = pad(raw) | |
| iv = Random.new().read(AES.block_size) | |
| cipher = AES.new(self.key, AES.MODE_CBC, iv) | |
| return b64encode(iv + cipher.encrypt(raw)) | |
| def decrypt(self, enc): | |
| enc = b64decode(enc) | |
| iv = enc[:16] | |
| cipher = AES.new(self.key, AES.MODE_CBC, iv) | |
| return unpad(cipher.decrypt(enc[16:])).decode('utf8') | |
| ## | |
| # MAIN | |
| # Just a test. | |
| msg = input('Message...: ') | |
| pwd = input('Password..: ') | |
| print('Ciphertext:', AESCipher(pwd).encrypt(msg)) |
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