python AES 加密与解密

#用aes加密，再用base64  encode
def aes_encrypt(data): 

    from Crypto.Cipher import AES
    import base64
    key=settings.aes_key  #加密时使用的key，只能是长度16,24和32的字符串
    BS = AES.block_size
    pad = lambda s: s + (BS - len(s) % BS) * chr(BS - len(s) % BS)
    cipher = AES.new(key)
    encrypted = cipher.encrypt(pad(data))  #aes加密
    result = base64.b64encode(encrypted)  #base64 encode
    return result  

#把加密的数据，用base64  decode，再用aes解密
def aes_decode(data):
    key=settings.aes_key
    from Crypto.Cipher import AES
    import os
    import base64
    unpad = lambda s : s[0:-ord(s[-1])]
    cipher = AES.new(key)
    result2 = base64.b64decode(data)
    decrypted = unpad(cipher.decrypt(result2))
    return  decrypted