/*
* Copyright (c) 2004 ???. All Rights Reserved.
* Download by http://www.codefans.net
* Version 1.0 , Created on 2004-3-10
*
*/
/**
* @author Devon
*/
/**
* 如何产生和保存密钥
*/
import java.security.*;
import java.security.spec.*;
import javax.crypto.*;
import java.io.*;
public class KeyGeneratorExample {
public static void main(String[] args) {
try{
//产生单钥加密的密钥(myKey)
KeyGenerator keyGenerator = KeyGenerator.getInstance("DESede"); //采用DESede算法
keyGenerator.init(168); //选择DESede算法,密钥长度为112位或168位
Key myKey = keyGenerator.generateKey(); //生成密钥
System.out.println("得到单钥加密密钥");
//产生双钥的密钥对(keyPair)
KeyPairGenerator keyPairGenerator=KeyPairGenerator.getInstance("RSA"); //采用RSA算法
keyPairGenerator.initialize(1024); //指定密钥长度为1024位
KeyPair keyPair = keyPairGenerator.generateKeyPair(); //生成密钥对
System.out.println("生成张三的公钥对");
//保存公钥的字节数组
File f = new File("publicKey.dat"); //保存公钥到文件publicKey.dat
FileOutputStream fout = new FileOutputStream(f);
fout.write(keyPair.getPublic().getEncoded()); //得到公钥的字节数组
fout.close(); //关闭文件输出流
System.out.println("保存公钥到文件: "+f.getAbsolutePath());
//用Java对象序列化保存私钥,通常应对私钥加密后再保存
ObjectOutputStream oout = new ObjectOutputStream(new FileOutputStream("privateKey.dat")); //保存私钥到文件privateKey.dat
oout.writeObject(keyPair.getPrivate()); //序列化私钥
oout.close(); //关闭输出流
System.err.println("保存私钥到: privateKey.dat");
//从文件中得到公钥编码的字节数组
FileInputStream fin = new FileInputStream("publicKey.dat"); //打天publicKey.dat
ByteArrayOutputStream baout = new ByteArrayOutputStream(); //用于写入文件的字节流
int aByte = 0;
while ((aByte = fin.read())!= -1) //从文件读取一个字节
{
baout.write(aByte); //写入一个字节
}
fin.close(); //关闭文件输入流
byte[] keyBytes = baout.toByteArray(); //得到公钥的字节数组
baout.close(); //关闭字节数组输出流
//从字节数组解码公钥
X509EncodedKeySpec x509KeySpec =new X509EncodedKeySpec(keyBytes);
KeyFactory keyFactory = KeyFactory.getInstance("RSA"); //指定算法RSA,得到一个KeyFactory的实例
PublicKey pubKey = keyFactory.generatePublic(x509KeySpec); //解码公钥
System.out.println("从文件中成功得到公钥");
}catch (Exception ex){ex.printStackTrace();
}
}
}
