Python AES加解密

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Python AES加解密

AES加密方式有五种：ECB, CBC, CTR, CFB, OFB

从安全性角度推荐CBC加密方法，本文介绍了CBC,ECB两种加密方法的python实现

python 在 Windows下使用AES时要安装的是pycryptodome 模块 pip install pycryptodome

python 在 Linux下使用AES时要安装的是pycrypto模块 pip install pycrypto

CBC加密需要一个十六位的key(密钥)和一个十六位iv(偏移量)

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import base64
from Crypto.Cipher import AES


# AES加密解密模块
class AESUtil:

    # 每块16的bytes长度,  即是PKCS5 这种方式,  和秘钥长度一致
    __BLOCK_SIZE_16 = AES.block_size  

    @staticmethod
    def add_to_16(text):   # 转bytes 并 补齐为16的倍数
        b_text = text.encode("utf-8")
        x = AESUtil.__BLOCK_SIZE_16 - (len(b_text) % AESUtil.__BLOCK_SIZE_16)
        if x != 0:
            text = text + chr(x) * x
        return text.encode('utf-8')

    @staticmethod
    def encrypt(text: str, key: bytes, mode: str="ECB", iv: bytes=None):
        """
        AES 加密方法
        :param text: 要加密的字符串
        :param key: 密钥
        :param mode: 模式，CBC or ECB
        :param iv: 偏移量（ECB模式没有偏移量）
        :return: 返回加密的数据
        """
        aes_mode = AES.MODE_CBC if mode == "CBC" else AES.MODE_ECB
        if iv and mode == "CBC":
            cipher = AES.new(key, aes_mode, iv)
        else:
            cipher = AES.new(key, aes_mode)
        text = AESUtil.add_to_16(text)
        msg = cipher.encrypt(text)
        msg = base64.b64encode(msg)
        return msg

    @staticmethod
    def decrypt(en_str: str, key: bytes, mode: str="ECB", iv: bytes=None):
        """
        AES 解密方法
        :param en_str: 要解密的字符串
        :param key: 密钥
        :param mode: 模式，CBC or ECB
        :param iv:  偏移量（ECB模式没有偏移量）
        :return:
        """
        aes_mode = AES.MODE_CBC if mode == "CBC" else AES.MODE_ECB
        if iv and mode == "CBC":
            cipher = AES.new(key, aes_mode, iv)
        else:
            cipher = AES.new(key, aes_mode)
        decrypt_bytes = base64.b64decode(en_str)
        msg = cipher.decrypt(decrypt_bytes)
        return msg.decode("utf-8")

# 测试
if __name__ == "__main__":
    key = b"1234567812345678"
    iv = b"1234567812345678"
    res = AESUtil.encrypt("123456", key, "CBC", iv)
    print(res)  # 2eDiseYiSX62qk/WS/ZDmg==
    print(AESUtil.decrypt(res, key, "CBC", iv))  # 123456

    key = b"1234567812345678"
    iv = b"1234567812345678"
    res = AESUtil.encrypt("123456", key)
    print(res)  # mdSm0RmB+xAKrTah3DG31A==
    print(AESUtil.decrypt(res, key))  # 123456

注：有的时候使用AES解密后，最后多出一些莫名其妙的字符，当我们使用json.loads时会出错，可以使用如下方式去除末尾多余字符：

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msg = cipher.decrypt(decrypt_bytes)
msg = msg.decode('utf-8')
unpadding = ord(msg[len(msg)-1])
return msg[0:length-unpadding]