为什么我不能在别人的AES解密中解密我的AES加密消息?

时间:2012-08-31 19:32:40

标签: python aes pycrypto

from Crypto.Cipher import AES
import os

key = 'mysecretpassword'
iv = os.urandom(16)
plaintext1 = 'Secret Message A'
encobj = AES.new(key, AES.MODE_CBC, iv)
ciphertext1 = encobj.encrypt(plaintext1) 
encryptedText = ciphertext1.encode('base64')
print encryptedText
decobj = AES.new(key, AES.MODE_CBC, iv)
print decobj.decrypt(ciphertext1)

我从代码中复制了encryptedTextkey的打印值并粘贴到以下网站。

http://www.everpassword.com/aes-encryptor

http://www.nakov.com/blog/2011/12/26/online-aes-encryptor-decryptor-javascript/

我希望它能够解密我的密码,但它没有。因此我必须使用pycrypto错误。我该如何解决?这两个站点可以相互加密和解密,但是地雷不能。这两个网站确实都使用CBC模式。

1 个答案:

答案 0 :(得分:3)

如果您查看相关网站的网页来源,您会看到它使用gibberish-aes javascript库。要想看到你必须做些什么来使其发挥作用,你必须研究它的作用。

查看其source code,它似乎使用随机盐进行加密。字符串Salted__前面的字符在它被base64编码之前形成了密文的开头。

randArr = function(num) {
    var result = [], i;
    for (i = 0; i < num; i++) {
        result = result.concat(Math.floor(Math.random() * 256));
    }
    return result;
},

enc = function(string, pass, binary) {
        // string, password in plaintext
        var salt = randArr(8),
        pbe = openSSLKey(s2a(pass, binary), salt),
        key = pbe.key,
        iv = pbe.iv,
        cipherBlocks,
        saltBlock = [[83, 97, 108, 116, 101, 100, 95, 95].concat(salt)];
        string = s2a(string, binary);
        cipherBlocks = rawEncrypt(string, key, iv);
        // Spells out 'Salted__'
        cipherBlocks = saltBlock.concat(cipherBlocks);
        return Base64.encode(cipherBlocks);
    },

对于解密,它使用在base64解码(第一个slice运算符)之后从密文的开头挑出盐的随机部分:

dec = function(string, pass, binary) {
    // string, password in plaintext
    var cryptArr = Base64.decode(string),
    salt = cryptArr.slice(8, 16),
    pbe = openSSLKey(s2a(pass, binary), salt),
    key = pbe.key,
    iv = pbe.iv;
    cryptArr = cryptArr.slice(16, cryptArr.length);
    // Take off the Salted__ffeeddcc
    string = rawDecrypt(cryptArr, key, iv, binary);
    return string;
},

现在缺少的部分是openSSLkey功能:

openSSLKey = function(passwordArr, saltArr) {
    // Number of rounds depends on the size of the AES in use
    // 3 rounds for 256
    // 2 rounds for the key, 1 for the IV
    // 2 rounds for 128
    // 1 round for the key, 1 round for the IV
    // 3 rounds for 192 since it's not evenly divided by 128 bits
    var rounds = Nr >= 12 ? 3: 2,
    key = [],
    iv = [],
    md5_hash = [],
    result = [],
    data00 = passwordArr.concat(saltArr),
    i;
    md5_hash[0] = GibberishAES.Hash.MD5(data00);
    result = md5_hash[0];
    for (i = 1; i < rounds; i++) {
        md5_hash[i] = GibberishAES.Hash.MD5(md5_hash[i - 1].concat(data00));
        result = result.concat(md5_hash[i]);
    }
    key = result.slice(0, 4 * Nk);
    iv = result.slice(4 * Nk, 4 * Nk + 16);
    return {
        key: key,
        iv: iv
    };
},

所以基本上你必须将openSSLKey函数翻译成Python并输入你的密码和盐。这创建了一个(key,iv)元组。使用它们来加密您的数据。在使用base64对字符串进行编码之前,将字符串Salted__和salt添加到密文。那么它应该可行,我想。