我们在做技术接口时，尤其对外提供时，为了提高服务接口的安全（防爆破，防重放，防篡改等）一般会采用接口验证的方式，但是在验证的时候为了提升参数请求前后的安全，我们会采用加密。普通加密基本都是对称的，不能逆向。

下面，我介绍一种RSA的算法，通过这个加密算法实现接口请求前后的数字签名验证。具体实现流程为：

下面我将RSA的签名算法代码分享下，下载即用：

public class RSAEncrypt {


    private static Map keyMap = new HashMap();  //用于封装随机产生的公钥与私钥

    private static String pirvateKey="MIIBUwIBADANBgkqhkiG9w0BAQEFAASCAT0wggE5AgEAAkEAgS8Vf8eKVf9YoqoyhFy4hHgYpNkSkrrmkJrfrKeZHfZWFx2cCoon74QZ3qw15VV9jMD5DWaPdMVAVx5HckNURwIDAQABAkBpS6Fwd4pwMiNi4usuLA1SHDmqFC0pYCISd8odBratTjRv6w9OH+A/CIKDir4DZ0PsS9qh0mxb0bthRQ9vS0wBAiEAx+y2VcrbnOZNQSWUONZcVKIHazkrAWXOBR8mQfJnOUcCIQClavCvg0SesKWv65vs2ZR0quQnaFdcCMh7B4GM2DCNAQIgAsXgvY3jv+hd1/J6fNNUUoQw0Cbp1sofsmh9Mlr3XY8CIFEyGex9Cay/VsTwaLws3PMbgxxY2jDB2u6Q86VX5RUBAiBhoiUOYrxrS77ifDFm1KYFHRPyZNStYJhcVu4U5kwwIA==";
    private static String publicKey="MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAIEvFX/HilX/WKKqMoRcuIR4GKTZEpK65pCa36ynmR32VhcdnAqKJ++EGd6sNeVVfYzA+Q1mj3TFQFceR3JDVEcCAwEAAQ==";
    private static String ssb="fSAUUCYm3FI3EYJWZRPXnI1dbwcLT3bFUqL5Wsdv24QtLmYmrN2i5WRKQgGxMTewRJ78Obf1Zke9rTpE+23zzw==";

    public static void main(String[] args) throws Exception {
        //生成公钥和私钥
        //genKeyPair();
        //String randomStr= RandomStrUtil.getRandom(24, RandomStrUtil.TYPE.LETTER_CAPITAL_NUMBER);
        String uuid=UUIDUtil.getUUID();
        String hashCode=String.valueOf(uuid.hashCode());
        System.out.println("hashcode="+hashCode);
        long time=System.currentTimeMillis();
        //System.out.println("随机hash"+hashCode);
        //加密字符串
        String message = time+"@=@"+uuid;
        //System.out.println("随机生成的公钥为:" + publicKey);
        //System.out.println("随机生成的私钥为:" + pirvateKey);
        String messageEn = encrypt(message,publicKey);
        System.out.println("加密后的字符串为:" + messageEn);
        String messageDe = decrypt(messageEn,pirvateKey);
        System.out.println("源文数据="+message);
        System.out.println("解密数据=" + messageDe);

        String bs=messageDe.split("@=@")[1];
        System.out.println(bs);
    }
    /**
     * 随机生成密钥对
     * @throws NoSuchAlgorithmException
     */
    public static void genKeyPair() throws NoSuchAlgorithmException {
        // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        // 初始化密钥对生成器，密钥大小为96-1024位
        keyPairGen.initialize(1024,new SecureRandom());
        // 生成一个密钥对，保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();
        // 得到私钥
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        // 得到公钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

        String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
        System.out.println("公钥="+publicKeyString);
        // 得到私钥字符串
        String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
        System.out.println("私钥="+privateKeyString);
        // 将公钥和私钥保存到Map
        //0表示公钥
        keyMap.put(0,publicKeyString);
        //1表示私钥
        keyMap.put(1,privateKeyString);
    }
    /**
     * RSA公钥加密
     *
     * @param str
     *            加密字符串
     * @param publicKey
     *            公钥
     * @return 密文
     * @throws Exception
     *             加密过程中的异常信息
     */
    public static String encrypt( String str, String publicKey ) throws Exception{
        //base64编码的公钥
        byte[] decoded = Base64.decodeBase64(publicKey);
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        //RSA加密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
        return outStr;
    }
    /**
     * RSA私钥解密
     *
     * @param str
     *            加密字符串
     * @param privateKey
     *            私钥
     * @return 铭文
     * @throws Exception
     *             解密过程中的异常信息
     */
    public static String decrypt(String str, String privateKey) throws Exception{
        //64位解码加密后的字符串
        byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
        //base64编码的私钥
        byte[] decoded = Base64.decodeBase64(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        //RSA解密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, priKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }
}