3DES加解密报错 Invalid key length: 32 bytes

淩亂°似流年 2022-05-31 14:50 187阅读 0赞

开发过程中用到3DES对敏感信息进行加密，秘钥用的是32位的，报出如下异常

Exception in thread "main" java.security.InvalidKeyException: Invalid key length: 32 bytes
        at com.sun.crypto.provider.DESedeCipher.engineGetKeySize(DESedeCipher.java:370)
        at javax.crypto.Cipher.passCryptoPermCheck(Cipher.java:1067)
        at javax.crypto.Cipher.checkCryptoPerm(Cipher.java:1025)
        at javax.crypto.Cipher.implInit(Cipher.java:801)
        at javax.crypto.Cipher.chooseProvider(Cipher.java:864)
        at javax.crypto.Cipher.init(Cipher.java:1249)
        at javax.crypto.Cipher.init(Cipher.java:1186)
        at com.adtec.des.des_temp.encryptThreeDESECB(des_temp.java:33)
        at com.adtec.des.des_temp.main(des_temp.java:61)

加密代码如下：

/** * * @param src 加密内容 * @param key 秘钥 32位长度 * @return 加密后的内容 * @throws Exception */
        public static byte[] encryptThreeDESECB(final String src, final String key) throws Exception {
    
            SecretKey securekey = new SecretKeySpec(key.getBytes(), "DESede");
    
            final Cipher cipher = Cipher.getInstance("DESede/ECB/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, securekey);
            final byte[] b = cipher.doFinal(src.getBytes());
    
            return b;
    
        }

测试用例

public static void main(String[] args) throws Exception {
            String key = "11112222333344445555666677778888";
            // 加密流程
            String telePhone = "123456";
            byte[] telePhone_encrypt = null;
            telePhone_encrypt = encryptThreeDESECB(URLEncoder.encode(telePhone, "UTF-8"), key);
            System.out.println(new String(telePhone_encrypt));
            // 解密流程
            String tele_decrypt = decryptThreeDESECB(telePhone_encrypt, key);
            System.out.println("解密:" + tele_decrypt);
        }

感觉不应该有问题啊？？？  
试着将秘钥长度减为24位  
![这里写图片描述][70]

这就可以了，但这是不可以的，系统不是我一个人操作，我用前24位加密，别人不知道，用后24位解密，就会导致结果不一致，无法解密。

知道我看见了另外一个方法：

/** * * @param src 加密内容 * @param key 秘钥 32位长度 * @return 加密后的内容 * @throws Exception */
        public static byte[] encryptThreeDESECB(final String src, final String key) throws Exception {
            final DESedeKeySpec dks = new DESedeKeySpec(key.getBytes("UTF-8"));
    
            final SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DESede");
            final SecretKey securekey = keyFactory.generateSecret(dks);
            final Cipher cipher = Cipher.getInstance("DESede/ECB/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, securekey);
            final byte[] b = cipher.doFinal(src.getBytes());
    
            return b;
    
        }

其他的一模一样

![这里写图片描述][70 1]

解密代码也一样

/** * * @param telePhone_encrypt 密文 * @param key 秘钥 32位长度 * @return 解密后明文 * @throws Exception */
        public static String decryptThreeDESECB(byte[] telePhone_encrypt, final String key) throws Exception {
            // --解密的key
            final DESedeKeySpec dks = new DESedeKeySpec(key.getBytes("UTF-8"));
            final SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DESede");
            final SecretKey securekey = keyFactory.generateSecret(dks);
    
            // --Chipher对象解密
            final Cipher cipher = Cipher.getInstance("DESede/ECB/PKCS5Padding");
            cipher.init(Cipher.DECRYPT_MODE, securekey);
            final byte[] retByte = cipher.doFinal(telePhone_encrypt);
    
            return new String(retByte);
        }

仔细看了一下有一行代码有重大嫌疑

final DESedeKeySpec dks = new DESedeKeySpec(key.getBytes("UTF-8"));

看一眼源码  
![这里写图片描述][70 2]

大概说的是，它用前24位构建DESedeKeySpec对象

再看看其DESedeKeySpec内部是如何实现的，打卡jdk的源码

/** * Uses the first 24 bytes in <code>key</code>, beginning at * <code>offset</code>, as the DES-EDE key * * @param key the buffer with the DES-EDE key * @param offset the offset in <code>key</code>, where the DES-EDE key * starts * * @exception InvalidKeyException if the given key has a wrong size */
    DESedeKey(byte[] key, int offset) throws InvalidKeyException {
    
        if (key==null || ((key.length-offset)<DESedeKeySpec.DES_EDE_KEY_LEN)) {
            throw new InvalidKeyException("Wrong key size");
        }
        this.key = new byte[DESedeKeySpec.DES_EDE_KEY_LEN];
        System.arraycopy(key, offset, this.key, 0,
                         DESedeKeySpec.DES_EDE_KEY_LEN);
        DESKeyGenerator.setParityBit(this.key, 0);
        DESKeyGenerator.setParityBit(this.key, 8);
        DESKeyGenerator.setParityBit(this.key, 16);
    
        // Use the cleaner to zero the key when no longer referenced
        final byte[] k = this.key;
        CleanerFactory.cleaner().register(this,
                () -> java.util.Arrays.fill(k, (byte)0x00));
    }

看到一个关键的东西：**DESedeKeySpec.DES\_EDE\_KEY\_LEN**  
![这里写图片描述][70 3]

果然长度是24

从底层源码

if (key==null || ((key.length-offset)<DESedeKeySpec.DES_EDE_KEY_LEN)) {
            throw new InvalidKeyException("Wrong key size");
        }

可以看出，如果秘钥为空或者小于24位会抛出**Wrong key size**，试一下  
![这里写图片描述][70 4]

再试一下超过32位的  
![这里写图片描述][70 5]

至此就可以发现了，后面这张加密方法，秘钥长度不能小于24，可以大于24，但是其实现的时候只截取了前24位

总结，推荐使用第二中加密方法，因为是底层截取的，不是我们手动截取的，无论是加密方还是解密方都遵循这个规则

[70]: /images/20220531/81f3cee5fe3b4293bb4c5a74d78ca854.png
[70 1]: /images/20220531/77f19742388f4abfa975311dc2a0496a.png
[70 2]: /images/20220531/19a3e033728d4806b089bff9e402681c.png
[70 3]: /images/20220531/9f490810506849c4adb83772283609d6.png
[70 4]: /images/20220531/e3387d1041e14772a7bbfd1b45105faf.png
[70 5]: /images/20220531/e6f9a559f8dd490ea8bb25bf7b1cc6c0.png