一 背景介绍

数字签名：带有密钥（公钥、私钥）的消息摘要算法。验证数据完整性、认证数据来源、抗否认。私钥签名、公钥验证。常用算法：RSA、DSA、ECDSA

二 RSA介绍

包括MD和SHA两类

三 Java代码实现

package com.imooc.security.rsa2;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.PrivateKey;import java.security.PublicKey;import java.security.Signature;import java.security.interfaces.RSAPrivateKey;import java.security.interfaces.RSAPublicKey;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import org.apache.commons.codec.binary.Hex;public class ImoocRSA {    private static String src = "cakin security rsa";    public static void main(String[] args) {        jdkRSA();    }    public static void jdkRSA() {        try {            //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();            //2.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(src.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(src.getBytes());            boolean bool = signature.verify(result);            System.out.println("jdk rsa verify : " + bool);        } catch (Exception e) {            e.printStackTrace();        }    }}

四 实现效果

jdk rsa sign : 64b62967438d05f8f9837a089aaecd3b1379fd8eef89b924632536deb95d94d8389da456014ee953a1ac1befe44612c61b750b48c8574b98a9855a07a724e7e4jdk rsa verify : true