search
LoginSignup
132

More than 5 years have passed since last update.

posted at

updated at

Pythonで暗号化と復号化

PyCryptoを使って、AES形式の暗号化を行う

$ pip install pycrypto
aes_cipher.py
import base64
from Crypto import Random
from Crypto.Cipher import AES

class AESCipher(object):
    def __init__(self, key, block_size=32):
        self.bs = block_size
        if len(key) >= len(str(block_size)):
            self.key = key[:block_size]
        else:
            self.key = self._pad(key)

    def encrypt(self, raw):
        raw = self._pad(raw)
        iv = Random.new().read(AES.block_size)
        cipher = AES.new(self.key, AES.MODE_CBC, iv)
        return base64.b64encode(iv + cipher.encrypt(raw))

    def decrypt(self, enc):
        enc = base64.b64decode(enc)
        iv = enc[:AES.block_size]
        cipher = AES.new(self.key, AES.MODE_CBC, iv)
        return self._unpad(cipher.decrypt(enc[AES.block_size:]))

    def _pad(self, s):
        return s + (self.bs - len(s) % self.bs) * chr(self.bs - len(s) % self.bs)

    def _unpad(self, s):
        return s[:-ord(s[len(s)-1:])]

後は、認証用の鍵を作成する。

$ python -c "import string, random; print(''.join([random.choice(string.ascii_letters + string.digits) for i in range(50)]))"

>>> PkDv17c6xxiqXPrvG2cUiq90VIrERfthHuViKapv6E1F7E0IgP

usage

cipher = AESCipher("PkDv17c6xxiqXPrvG2cUiq90VIrERfthHuViKapv6E1F7E0IgP")

# 暗号化
password = cipher.encrypt("hogefuga")
print(password) # -> H/LfZg82FOdHhnructCHzfYnVgCOvjgEUGXXDFpjiYLBHw4Zflk/m2N9zEVwz6eC

#復号化
print(cipher.decrypt(password)) # -> hogefuga

追記

ちょいちょいストックされていて需要がありそうなので、PyPIに登録しました。

$ pip install Simple-AES-Cipher

詳しくはGithubをご覧ください。

参考

Advanced Encryption Standard
PyCryptoで暗号化する

Register as a new user and use Qiita more conveniently

  1. You get articles that match your needs
  2. You can efficiently read back useful information
What you can do with signing up
132