JAVA加解密 -- 数字签名算法

数字签名 – 带有密钥的消息摘要算法
作用：验证数据完整性、认证数据来源、抗否认（OSI参考模型）
私钥签名，公钥验证
RSA 包含非对称算法和数字签名算法


实现代码:

  //1.初始化密钥
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            keyPairGenerator.initialize(512);
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
            RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();

            //执行签名
            PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
            Signature signature = Signature.getInstance("MD5withRSA");
            signature.initSign(privateKey);
            signature.update(str.getBytes());
            byte[] result = signature.sign();
            System.out.println("JDK RSA SIGN:" + Hex.encodeHexString(result));

            //3.验证签名
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());
            keyFactory = keyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
            signature = Signature.getInstance("MD5withRSA");
            signature.initVerify(publicKey);
            signature.update(str.getBytes());
            boolean falg = signature.verify(result);
            System.out.println("JDK RSA VERIFY:"+falg);

DSA DSS -- 数字签名标准 DSA仅包含数字签名
ECDSA 椭圆曲线数字签名算法，JDK1.7之后才有的内容
    实现方式和RSA一致  只需将指定地方改为EC,再在首句加上Security.addProvider(new BouncyCastlePQCProvider());即可

    JAVA加解密算法源码:http://download.csdn.net/detail/jacxuan/9774737