java encryption and decryption mode

1, MD5 (Message Digest Algorithm) encryption algorithm

是一种单向加密算法，只能加密不能解密，示例

/**
     * MD5 simple encryption
     * @Param Content encrypted content
     * @return String
     */
    public static String md5Encrypt(final String content) {

        MessageDigest md5 = null;
        try {
            md5 = MessageDigest.getInstance(ALGORITHM_MD5);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace ();
        }
//         md5.update (text.getBytes ());
         // Digest () Returns the last md5 hash value, the return value is 8 bit string. Because md5 hash value is a hex value of 16, 8-bit characters is actually
         // convert BigInteger 8 will function as a string of hex 16 value, is represented by a string; string of the hash value obtained 
        BigInteger = Digest new new a BigInteger (md5.digest (content.getBytes ()));
         // 32 bit 
        return digest.toString (16 );
    }

2, BASE64 encrypt / decrypt

通常用作对二进制数据进行加密，示例

/**
     * Base64 encryption
     * @Param Content content to be encrypted
     * @return byte[]
     */
    public static byte[] base64Encrypt(final String content) {
        return Base64.getEncoder().encode(content.getBytes());
    }

    /**
     * Base64 decryption
     * @Param encoderContent encrypted content
     * @return byte[]
     */
    public static byte[] base64Decrypt(final byte[] encoderContent) {
        return Base64.getDecoder().decode(encoderContent);
    }

3, DES (Data Encryption Standard) symmetric encryption / decryption

数据加密标准算法,和BASE64最明显的区别就是有一个工作密钥，该密钥既用于加密、也用于解密，并且要求密钥是一个长度至少大于8位的字符串，示例

/**
     * DES encryption
     * @param key 秘钥key
     * @Param Content content to be encrypted
     * @return byte[]
     */
    public static byte[] DESEncrypt(final String key, final String content) {
        return processCipher(content.getBytes(), getSecretKey(key), Cipher.ENCRYPT_MODE , ALGORITHM_DES);
    }

    /**
     * DES decryption
     * @param key 秘钥key
     * @Param encoderContent encrypted content
     * @return byte[]
     */
    public static byte[] DESDecrypt(final String key, final byte[] encoderContent) {
        return processCipher(encoderContent, getSecretKey(key), Cipher.DECRYPT_MODE, ALGORITHM_DES);
    }

4, RSA asymmetric encryption / decryption

非对称加密算法的典型代表，既能加密、又能解密。和对称加密算法比如DES的明显区别在于用于加密、解密的密钥是不同的。使用RSA算法，只要密钥足够长(一般要求1024bit)，加密的信息是不能被破解的。示例

/**
     * RSA encryption
     * @Param Content content to be encrypted
     * @return byte[]
     */
    public static byte[] RSAEncrypt(final String content) {
        return processCipher(content.getBytes(), keyPair.getPrivate(), Cipher.ENCRYPT_MODE , ALGORITHM_RSA);
    }

    /**
     * RSA decryption
     * @Param encoderContent encrypted content
     * @return byte[]
     */
    public static byte[] RSADecrypt(final byte[] encoderContent) {
        return processCipher(encoderContent, keyPair.getPublic(), Cipher.DECRYPT_MODE, ALGORITHM_RSA);
    }

5, SHA (Secure Hash Algorithm, Secure Hash Algorithm)

数字签名等密码学应用中重要的工具，被广泛地应用于电子商务等信息安全领域，示例

/**
     * SHA encryption
     * @Param Content content to be encrypted
     * @return String
     */
    public static String SHAEncrypt(final String content) {
        try {
            MessageDigest sha = MessageDigest.getInstance(ALGORITHM_SHA);
            byte[] sha_byte = sha.digest(content.getBytes());
            HexValue the StringBuffer = new new the StringBuffer ();
             for ( byte B: sha_byte) {
                 // in which each byte is converted to a hexadecimal string: byte data type highest bit is the sign bit, and for the operation through 0xff the conversion is a positive integer of type int. 
                Integer.toHexString toHexString = String (B & 0xFF );
                hexValue.append(toHexString.length() == 1 ? "0" + toHexString : toHexString);
            }
            return hexValue.toString();

//            StringBuffer hexValue2 = new StringBuffer();
//            for (int i = 0; i < sha_byte.length; i++) {
//                int val = ((int) sha_byte[i]) & 0xff;
//                if (val < 16) {
//                    hexValue2.append("0");
//                }
//                hexValue2.append(Integer.toHexString(val));
//            }
//            return hexValue2.toString();
        } catch (Exception e) {
            e.printStackTrace ();
        }
       return "";
    }

6, HMAC (Hash Message Authentication Code, Hash Message Authentication Code)

使用一个密钥生成一个固定大小的小数据块，即MAC，并将其加入到消息中，然后传输。接收方利用与发送方共享的密钥进行鉴别认证，示例


/**
     * HMAC encryption
     * @Param key given keys key
     * @Param Content content to be encrypted
     * @return String
     */
    public static byte[] HMACEncrypt(final String key, final String content) {
        try {
            SecretKey secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM_MAC);
            Mac mac = Mac.getInstance(secretKey.getAlgorithm());
            //初始化mac
            mac.init(secretKey);
            return mac.doFinal(content.getBytes());
        } catch (Exception e) {
            e.printStackTrace ();
        }
        return null;
    }

Test code:

public  static  void main (String [] args) {
         // MD5 simple encryption 
        String text = "text I AM" ;
        System.out.println(EnDecoderUtil.md5Encrypt(text));

        // Base64 encryption and decryption, is generally used for encrypting binary data 
        byte [] = base64Encrypt EnDecoderUtil.base64Encrypt ( "123456789" );
        String toHexString = HexUtils.toHexString(base64Encrypt);
        System.out.println(toHexString);
        byte[] base64Decrypt = EnDecoderUtil.base64Decrypt(base64Encrypt);
        System.out.println(new String(base64Decrypt));

        // the DES symmetric encryption / decryption
         // required key length of at least 8 characters 
        String key = "123456789" ;
         // encrypted 
        byte [] = encode_bytes EnDecoderUtil.DESEncrypt (key, "the Hello, the DES" );
        System.out.println(Base64.getEncoder().encodeToString(encode_bytes));
        //解密
        byte[] decode_bytes = EnDecoderUtil.DESDecrypt(key, encode_bytes);
        System.out.println(new String(decode_bytes));

        // the RSA
         // Data encrypted using a private 
        byte [] = en_byte EnDecoderUtil.RSAEncrypt ( "the Hi, the RSA" );
        System.out.println(Base64.getEncoder().encodeToString(en_byte));

        // user public key to decrypt 
        byte [] = de_byte EnDecoderUtil.RSADecrypt (en_byte);
        System.out.println(new String(de_byte));

        // server generates a private key and a digital signature from the encrypted data 
        byte [] = sign_byte EnDecoderUtil.getSignature (en_byte);
        System.out.println(Base64.getEncoder().encodeToString(sign_byte));

        // user according to the public key, the encrypted data to verify whether the data has been modified 
        Boolean verify_result = EnDecoderUtil.verifySignature (en_byte, sign_byte);
        System.out.println(verify_result);

        //SHA
        String sha = EnDecoderUtil.SHAEncrypt("Hi, RSA");
        System.out.println(sha);

        //HMAC
        byte[] mac_bytes = EnDecoderUtil.HMACEncrypt(key, "Hi, HMAC");
        System.out.println(HexUtils.toHexString(mac_bytes));
    }

 

Source reference Github