DES加密在linux下的问题

旧城等待， 2022-05-22 03:46 141阅读 0赞

最近写了段DES加密的代码

// 指定DES加密解密所用的秘钥
        private static Key key;
        private static String KEY_STR = "dashuaigege19931130";
        static {
            try {
                KeyGenerator generator = KeyGenerator.getInstance("DES");
                generator.init(new SecureRandom(KEY_STR.getBytes()));
                key = generator.generateKey();
                generator = null;
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    
        // 对字符串进行DES加密，返回BASE64编码的加密字符串
        public static String getEncryptString(String str) {
            Base64 base64 = new Base64();
            try {
                byte[] strBytes = str.getBytes("UTF8");
                Cipher cipher = Cipher.getInstance("DES");
                cipher.init(Cipher.ENCRYPT_MODE, key);
                byte[] encryptStrBytes = cipher.doFinal(strBytes);
                return base64.encodeToString(encryptStrBytes);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    
        // 对BASE64编码的加密字符串进行解密，返回解密后的字符串
        public static String getDecryptString(String str) {
            Base64 base64 = new Base64();
            try {
                byte[] strBytes = base64.decode(str);
                Cipher cipher = Cipher.getInstance("DES");
                cipher.init(Cipher.DECRYPT_MODE, key);
                byte[] decryptStrBytes = cipher.doFinal(strBytes);
                return new String(decryptStrBytes, "UTF8");
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }

在windows环境下完美运行。但是当我把程序移到linux下的到时候，就报错了  
Caused by: javax.crypto.BadPaddingException: Given final block not properly padded. Such issues can arise if a bad key is used during decryption.  
![这里写图片描述][70]  
看堆栈是解密的时候报错了。经过检查，其实与解密问题，问题出现在了生成Key的时候。  
再来看下这段代码

KeyGenerator generator = KeyGenerator.getInstance("DES");
                generator.init(new SecureRandom(KEY_STR.getBytes()));
                key = generator.generateKey();
                generator = null;

问题就出在 **new SecureRandom(KEY\_STR.getBytes())** 上。SecureRandom类提供加密的强随机数生成器，在windows环境下每次都将会生成相同的Key值。但是在linux环境下则不同，SecureRandom尝试实现完全随机化的内部状态。因此可以对其指定算法名称

SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG" );

系统将确定环境中是否有其所请求的算法，是否有多个，是否去首选实现。  
其次再调用

secureRandom.setSeed(strKey.getBytes());

这样就能生成固定的Key值  
因此，可改为如下代码：

try {
                KeyGenerator generator = KeyGenerator.getInstance("DES");
                SecureRandom secureRandom=SecureRandom.getInstance("SHA1PRNG");
                secureRandom.setSeed(KEY_STR.getBytes());
                generator.init(secureRandom);
                key = generator.generateKey();
                generator = null;
            } catch (Exception e) {
                throw new RuntimeException(e);
            }

参考[https://wenku.baidu.com/view/b968921514791711cc791778.html][https_wenku.baidu.com_view_b968921514791711cc791778.html]

[70]: /images/20220522/584c6527f45542d894377df6c8337b75.png
[https_wenku.baidu.com_view_b968921514791711cc791778.html]: https://wenku.baidu.com/view/b968921514791711cc791778.html