java安全~RSA数字签名算法学习

数字签名算法

签名具有安全性、抗否认性的特点
，数字签名——带有密钥（公钥、私钥）的消息摘要算法，用于验证数据完整性、认证数据来源、抗否认，遵循OSI参考模型、私钥签名和公钥验证。常用数字签名算法RSA、DSA、ECDSA。

RSA算法包括MD、SHA经典算法两类如下

DSA：仅包含数字签名，不能进行加密通信的。
RSA：既能加解密，也包含数字签名。

ECDSA全名 Elliptic Curve Digital Signature Algorithm ,椭圆曲线数字签名算法
优点：速度快、强度高、签名短

RSAUtil.java

package com.pro.rsa;

import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
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 java.util.HashMap;

import org.apache.commons.codec.binary.Hex;

public class RSAUtil {
    /**
     * 生成公钥和私钥
     * @return
     * @throws NoSuchAlgorithmException
     */
    public static HashMap<String, Object> getKeys() {
        HashMap<String, Object> map = new HashMap<String, Object>();
        KeyPairGenerator generator = null;
        try {
            generator = KeyPairGenerator.getInstance("RSA");
        } catch (Exception e) {
            return null;
        }
        generator.initialize(1024);
        KeyPair keyPair = generator.generateKeyPair();
        RSAPublicKey rsapubKey = (RSAPublicKey)keyPair.getPublic();
        RSAPrivateKey rsapriKey = (RSAPrivateKey)keyPair.getPrivate();
        map.put("pubKey", rsapubKey);
        map.put("priKey", rsapriKey);
        return map;
    }
    /**
     * 私密加密
     * @param data
     * @param priKey
     * @return
     * @throws Exception
     */
    public static String encryptByPriKey(String data, RSAPrivateKey priKey){
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(priKey.getEncoded());
        KeyFactory keyFactory;
        PrivateKey key;
        Signature sign;
        byte[] result = null;
        try {
            keyFactory = KeyFactory.getInstance("RSA");
            key = keyFactory.generatePrivate(keySpec);
            sign = Signature.getInstance("MD5withRSA");
            sign.initSign(key);
            sign.update(data.getBytes());// 处理的内容
            result = sign.sign();
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("rsa sign:"+Hex.encodeHexString(result));
        System.out.println("sign len:"+result.length+",str hex:"+Hex.encodeHexString(result).length());
        return Hex.encodeHexString(result);
    }
    /**
     * 公钥验证
     * @param data
     * @param pubKey
     * @param res
     * @return
     * @throws Exception
     */
    public static boolean decryptByPubKey(String data, RSAPublicKey pubKey, String res) {
        System.out.println("res len:"+res.length());
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(pubKey.getEncoded());
        KeyFactory keyFactory;
        PublicKey key;
        Signature sign;
        boolean result = false;
        try {
            keyFactory = KeyFactory.getInstance("RSA");
            key = keyFactory.generatePublic(x509KeySpec);
            sign = Signature.getInstance("MD5withRSA");
            sign.initVerify(key);
            sign.update(data.getBytes());
            result = sign.verify(Hex.decodeHex(res.toCharArray()));
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("rsa verify:"+result);
        return result;
    }    
}

RSA.java

package com.pro.rsa;

import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.HashMap;

public class RSA {

    public final static String src = "hello world hello world hello world hello world hello world hello worldhello worldhello world hello world hello world hello world hello worldhello world hello world hello world hello world v hello world hello world hello world vhello world hello world";
    public final static String _src = "hello world hello world hello world hello world hello world hello worldhello worldhello world hello world hello world hello world hello worldhello world hello world hello world hello world v hello world hello world hello world vhello world hello world";
    public static void main(String[] args) {
        // 登录rosp返回给客户端
        HashMap<String, Object> map = RSAUtil.getKeys();
        RSAPublicKey pubKey = (RSAPublicKey) map.get("pubKey");
        RSAPrivateKey priKey = (RSAPrivateKey) map.get("priKey");
        // 客户端get提交给服务器
        String res= RSAUtil.encryptByPriKey(src, priKey);
        // 服务端验证
        RSAUtil.decryptByPubKey(_src, pubKey, res);
    }
}

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