使用CryptoJS解密AES/CBC/PKCS5Padding [英] Decrypt AES/CBC/PKCS5Padding with CryptoJS

问题描述

我使用Java javax.crypto API生成了128位的 AES/CBC/PKCS5Padding 密钥.这是我使用的算法:

I generate 128bit AES/CBC/PKCS5Padding key using Java javax.crypto API. Here is the algorithm that I use:

public static String encryptAES(String data, String secretKey) {
    try {
        byte[] secretKeys = Hashing.sha1().hashString(secretKey, Charsets.UTF_8)
                .toString().substring(0, 16)
                .getBytes(Charsets.UTF_8);

        final SecretKey secret = new SecretKeySpec(secretKeys, "AES");

        final Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, secret);

        final AlgorithmParameters params = cipher.getParameters();

        final byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();
        final byte[] cipherText = cipher.doFinal(data.getBytes(Charsets.UTF_8));

        return DatatypeConverter.printHexBinary(iv) + DatatypeConverter.printHexBinary(cipherText);
    } catch (Exception e) {
        throw Throwables.propagate(e);
    }
}


public static String decryptAES(String data, String secretKey) {
    try {
        byte[] secretKeys = Hashing.sha1().hashString(secretKey, Charsets.UTF_8)
                .toString().substring(0, 16)
                .getBytes(Charsets.UTF_8);

        // grab first 16 bytes - that's the IV
        String hexedIv = data.substring(0, 32);

        // grab everything else - that's the cipher-text (encrypted message)
        String hexedCipherText = data.substring(32);

        byte[] iv = DatatypeConverter.parseHexBinary(hexedIv);
        byte[] cipherText = DatatypeConverter.parseHexBinary(hexedCipherText);

        final Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

        cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(secretKeys, "AES"), new IvParameterSpec(iv));

        return new String(cipher.doFinal(cipherText), Charsets.UTF_8);
    } catch (BadPaddingException e) {
        throw new IllegalArgumentException("Secret key is invalid");
    }catch (Exception e) {
        throw Throwables.propagate(e);
    }
}

通过这些方法，我可以使用secretKey轻松加密和解密消息.由于Java默认具有128位AES加密，因此它将使用SHA1生成原始密钥的哈希，并使用哈希的前16个字节将其用作AES中的密钥.然后以HEX格式转储IV和cipherText.

I can easily encrypt and decrypt messages using secretKey with these methods. Since Java has 128bit AES encryption by default, it generates a hash of the original secret key with SHA1 and takes the first 16-bytes of the hash to use it as secret key in AES. Then it dumps the IV and cipherText in HEX format.

例如 encryptAES("test"，"test")生成 CB5E759CE5FEAFEFCC9BABBFD84DC80C0291ED4917CF1402FF03B8E12716E44C ，我想用CryptoJS解密此密钥.

For example encryptAES("test", "test") generates CB5E759CE5FEAFEFCC9BABBFD84DC80C0291ED4917CF1402FF03B8E12716E44C and I want to decrypt this key with CryptoJS.

这是我的尝试:

var str = 'CB5E759CE5FEAFEFCC9BABBFD84DC80C0291ED4917CF1402FF03B8E12716E44C';

CryptJS.AES.decrypt( 
CryptJS.enc.Hex.parse(str.substring(32)),
CryptJS.SHA1("test").toString().substring(0,16),  
{
  iv: CryptJS.enc.Hex.parse(str.substring(0,32)),
  mode: CryptJS.mode.CBC,
  formatter: CryptJS.enc.Hex, 
  blockSize: 16,  
  padding: CryptJS.pad.Pkcs7 
}).toString()

但是它返回一个空字符串.

However it returns an empty string.

推荐答案

问题是您将64位密钥用作128位密钥. Hashing.sha1().hashString(secretKey，Charsets.UTF_8)是

The problem is that you're using a 64 bit key as a 128 bit. Hashing.sha1().hashString(secretKey, Charsets.UTF_8) is an instance of HashCode and its toString method is described as such:

按顺序返回一个字符串，该字符串包含asBytes()的每个字节，为小写的两位数字无符号十六进制数.

Returns a string containing each byte of asBytes(), in order, as a two-digit unsigned hexadecimal number in lower case.

它是十六进制编码的字符串.如果仅使用该字符串的16个字符并将其用作键，则只有64位的熵而不是128位.您确实应该直接使用 HashCode#asBytes().

It is a Hex-encoded string. If you take only 16 characters of that string and use it as a key, you only have 64 bits of entropy and not 128 bits. You really should be using HashCode#asBytes() directly.

无论如何，CryptoJS代码的问题有很多:

Anyway, the problem with the CryptoJS code is manyfold:

• 密文必须是一个 CipherParams 对象，但是如果它在 ciphertext 属性中包含作为WordArray的密文字节就足够了.
• 密钥必须以WordArray而不是字符串的形式传递.否则，将使用与OpenSSL兼容的(EVP_BytesToKey)密钥派生函数从字符串(假定为密码)中派生密钥和IV.
• 附加选项不是必需的，因为它们是默认值，或者它们是错误的，因为blockSize是用字而不是字节计算的.

• The ciphertext must be a CipherParams object, but it is enough if it contains the ciphertext bytes as a WordArray in the ciphertext property.
• The key must be passed in as a WordArray instead of a string. Otherwise, an OpenSSL-compatible (EVP_BytesToKey) key derivation function is used to derive the key and IV from the string (assumed to be a password).
• Additional options are either unnecessary, because they are defaults, or they are wrong, because the blockSize is calculated in words and not bytes.

以下是与损坏的Java代码兼容的CryptoJS代码:

Here is CryptoJS code that is compatible with your broken Java code:

var str = 'CB5E759CE5FEAFEFCC9BABBFD84DC80C0291ED4917CF1402FF03B8E12716E44C';

console.log("Result: " + CryptoJS.AES.decrypt({
    ciphertext: CryptoJS.enc.Hex.parse(str.substring(32))
}, CryptoJS.enc.Utf8.parse(CryptoJS.SHA1("test").toString().substring(0,16)),  
{
  iv: CryptoJS.enc.Hex.parse(str.substring(0,32)),
}).toString(CryptoJS.enc.Utf8))

<script src="https://cdn.rawgit.com/CryptoStore/crypto-js/3.1.2/build/rollups/sha1.js"></script>
<script src="https://cdn.rawgit.com/CryptoStore/crypto-js/3.1.2/build/rollups/aes.js"></script>

以下是与固定Java代码兼容的CryptoJS代码:

Here is CryptoJS code that is compatible with the fixed Java code:

var str = 'F6A5230232062D2F0BDC2080021E997C6D07A733004287544C9DDE7708975525';

console.log("Result: " + CryptoJS.AES.decrypt({
    ciphertext: CryptoJS.enc.Hex.parse(str.substring(32))
}, CryptoJS.enc.Hex.parse(CryptoJS.SHA1("test").toString().substring(0,32)),  
{
  iv: CryptoJS.enc.Hex.parse(str.substring(0,32)),
}).toString(CryptoJS.enc.Utf8))

<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/rollups/sha1.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/rollups/aes.js"></script>

CryptoJS中的等效加密代码如下所示:

The equivalent encryption code in CryptoJS would look like this:

function encrypt(plaintext, password){
    var iv = CryptoJS.lib.WordArray.random(128/8);
    var key = CryptoJS.enc.Hex.parse(CryptoJS.SHA1(password).toString().substring(0,32));
    var ct = CryptoJS.AES.encrypt(plaintext, key, { iv: iv });
    return iv.concat(ct.ciphertext).toString();
}

console.log("ct: " + encrypt("plaintext", "test"));

<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/rollups/sha1.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/rollups/aes.js"></script>

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