【web_逆向08】对称加密之AES、DES

对称解密

• 所谓对称加密就是加密和解密用的是同一个秘钥. 就好比. 我要给你邮寄一个箱子. 上面怼上锁. 提前我把钥匙给了你一把, 我一把. 那么我在邮寄之前就可以把箱子锁上. 然后快递到你那里. 你用相同的钥匙就可以打开这个箱子.

• 常见的对称加密: AES, DES, 3DES等

安装第三方模块

• pip install pycrypto => 很多人装不上....
• pip install pycryptodome => 可以装..
• AES源码

# 创建加密器
# 秘钥必须是 16, 24, 32位字节...
# 99%的网站使用的aes都是16位秘钥..

# mode: AES的加密方式
# 常见的mode:
# ECB,  可以没有iv
# CBC,  必须有iv. 长度是16字节..
def new(key, mode, *args, **kwargs):
    """Create a new AES cipher.

    Args:
      key(bytes/bytearray/memoryview):
        The secret key to use in the symmetric cipher.

        It must be 16 (*AES-128)*, 24 (*AES-192*) or 32 (*AES-256*) bytes long.

        For ``MODE_SIV`` only, it doubles to 32, 48, or 64 bytes.
      mode (a ``MODE_*`` constant):
        The chaining mode to use for encryption or decryption.
        If in doubt, use ``MODE_EAX``.

    Keyword Args:
      iv (bytes/bytearray/memoryview):
        (Only applicable for ``MODE_CBC``, ``MODE_CFB``, ``MODE_OFB``,
        and ``MODE_OPENPGP`` modes).

        The initialization vector to use for encryption or decryption.

        For ``MODE_CBC``, ``MODE_CFB``, and ``MODE_OFB`` it must be 16 bytes long.

        For ``MODE_OPENPGP`` mode only,
        it must be 16 bytes long for encryption
        and 18 bytes for decryption (in the latter case, it is
        actually the *encrypted* IV which was prefixed to the ciphertext).

        If not provided, a random byte string is generated (you must then
        read its value with the :attr:`iv` attribute).
    """

使用案例

from Crypto.Cipher import AES
from Crypto.Util.Padding import pad,unpad
import base64,json

## 加密
def encrypt(s:str):
    # 准备加密器
    aes = AES.new(key=b'1234567890123456',mode=AES.MODE_CBC,iv=b'qwertyuioplkjhgf')
    #将需要加密的数据处理成字节
    bs = s.encode()
    # 要求数据的长度必须是16的倍数.不够的需要填充.
    bs_pad = pad(bs,16)  # 默认的填充方式 pkcs7
    # 加密
    mi_wen = aes.encrypt(bs_pad)

    #加密后是字节，需要使用base64编码后 还原成字符串
    ret = base64.b64encode(mi_wen).decode()
    return ret   #  rIRmEG7oqVCFOEvaCjTMlXH+BjhluQVp6l/Hq6guEHM=


## 解密
def decrypt(s:str):
    # 创建解密器
    aes2 = AES.new(key=b'1234567890123456',mode=AES.MODE_CBC,iv=b'qwertyuioplkjhgf')

    # 将密文转换成字节
    mi_bs = base64.b64decode(s)
    #解密
    ming_bs = aes2.decrypt(mi_bs)
    #解密后，去除填充---解码成字符串
    ret2 = unpad(ming_bs,16).decode('utf-8')
    return ret2

if __name__ == '__main__':
    dic = {
        "name": "xwl",
        "password": 18
    }
    s = json.dumps(dic,separators=(',', ':'))
    miwen = encrypt(s)
    print(f'miwen===>{miwen}')

    mingwen = decrypt(miwen)
    print(f'mingwen===>>>{mingwen}')


""""
运行结果
miwen===>rIRmEG7oqVCFOEvaCjTMlXH+BjhluQVp6l/Hq6guEHM=
mingwen===>>>{"name":"xwl","password":18}
"""

DES加密

• 与AES几乎一致

from Crypto.Cipher import DES, AES, DES3
from Crypto.Util.Padding import pad, unpad
import base64

# s = "雪中悍刀行"
# des = DES.new(key=b'12345678', mode=DES.MODE_CBC, iv=b'55511122')
# result = des.encrypt(pad(s.encode("utf-8"), 8))
# print(base64.b64encode(result).decode())

# # DES解密
# s = "KTF6QlkTXPN1qhcBtm6mUzZh4XLqzJsw"
# des = DES.new(key=b'12345678', mode=DES.MODE_CBC, iv=b'55511122')
# ming_bs = des.decrypt(base64.b64decode(s))
# print(unpad(ming_bs, 8).decode("utf-8"))