Java安全（JCA/JSSE）：数字签名

数字签名【你的数据的数字摘要，用私钥加密，我用公钥解密成功，那说明这个数据就是你的】

你的公钥必须到公安机关或者权威机构去备案。

package com.xiongshiyan.security;

 

import java.io.ByteArrayOutputStream;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.OutputStream;

importjava.security.Key;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

importjava.security.NoSuchAlgorithmException;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.Signature;

//私钥加密 公钥解密

publicclass DataSign {

 

    /**

     * @param args

     * @throwsException

     */

    publicstaticvoid main(String[] args)throws Exception {

       //TODO Auto-generatedmethod stub

       DataSign.sign();

       DataSign.verify();

    }

 

    privatestaticvoid sign()throws Exception{

       KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");//非对称加密方式

       KeyPair keyPair = keyPairGenerator.generateKeyPair();

       PublicKey publicKey = keyPair.getPublic();

       PrivateKey privateKey = keyPair.getPrivate();

      

       Signature signature = Signature.getInstance("MD5WithRSA");

       signature.initSign(privateKey);//私钥加密md5

      

       signature.update("给你一百万，绝不反悔".getBytes());

       byte[] signed=signature.sign();

      

      

       //把加密后的数据和key一起给别人 别人拿到了之后进行恢复

       ObjectOutputStream oosKey=new ObjectOutputStream(new FileOutputStream("key3.key"));

       oosKey.writeObject(publicKey);//写入加密key

       oosKey.close();

      

       FileOutputStream oosDat=new FileOutputStream("dat3.dat");

       oosDat.write(signed);//写入加密dat

       oosDat.close();

    }

    privatestaticvoid verify()throws Exception{

       Signature signature = Signature.getInstance("MD5WithRSA");

       ObjectInputStream oisKey=new ObjectInputStream(new FileInputStream("key3.key"));

       PublicKey publicKey=(PublicKey)oisKey.readObject();

       oisKey.close();

      

       signature.initVerify(publicKey);

      

       signature.update("给你一百万，绝不反悔".getBytes());

      

       FileInputStream fisDat=new FileInputStream("dat3.dat");

       ByteArrayOutputStream baos=new ByteArrayOutputStream();

       DataSign.copyStream(fisDat, baos);

       byte[] deSecResult=baos.toByteArray();

       boolean isYours=signature.verify(deSecResult);

      

       System.out.println(isYours);

      

    }

    privatestaticvoid copyStream(InputStream is,OutputStream os) throws Exception{

       byte[] buff=newbyte[1024];

       inttotal=0;

       int len=is.read(buff);

       while(len!=-1){

           os.write(buff, 0, len);

           len=is.read(buff);

       }

    }

}