java对称加为密DESede 与 非对称加密RSA 示例

对称密钥

EncryptDecryptData.java:

package com.cjq.save;


import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;

//对称密钥
public class EncryptDecryptData {
	static String plaintext = "12345678123456781234567812345678";

	public static void main(String[] args) throws Exception {
		System.out.println("明文");
		System.out.println(plaintext);
		//转换为字节数组，指定字符串特征为UTF8，以使不同平台加、解密时不引起错误
		byte[] plaintext1 = plaintext.getBytes("UTF8");
		//创建一个密钥生成器对象，加密算法为DESede
		KeyGenerator keygen = KeyGenerator.getInstance("DESede");
		keygen.init(168);
		//获得密钥
		SecretKey secretkey = keygen.generateKey();
		
		byte[] kb = secretkey.getEncoded();
//		int i=0;
		System.out.println("密钥:");
		for(int i=0;i<kb.length;i++){
			System.out.print(kb[i]+",");
			if(i%8==7) System.out.println();
		}
		//创建要求的加密对象，加密算法为DESede
		Cipher cipher = Cipher.getInstance("DESede");
		//加密对象初始化
		cipher.init(Cipher.ENCRYPT_MODE, secretkey);
		
		byte[] encrypted = cipher.doFinal(plaintext1);
		
		System.out.println("密文:");
		for(int i=0;i<encrypted.length;i++){
			System.out.print(encrypted[i]+",");
			if(i%8==7) System.out.println();
		}
		//对象cipher初始化成解密模式
		cipher.init(Cipher.DECRYPT_MODE, secretkey);
		byte[] decrypted = cipher.doFinal(encrypted);
		
		String str = new String(decrypted);
		System.out.println("解密后的原文:");
		System.out.println(str);
		
		
		
	}

}

非对称密钥

RSAEncryptData.java

package com.cjq.save;

import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;

//非对称密钥
public class RSAEncryptData {

	public static void main(String[] args) throws Exception{
		//创建一个密钥生成器对象，选择加密算法RSA
		KeyPairGenerator keygen = KeyPairGenerator.getInstance("RSA");
		//初始化对象生成器，RSA密钥长度510－2048
		keygen.initialize(1024);
		//生成密钥对
		KeyPair kp = keygen.genKeyPair();
		//获得公钥
		PublicKey pbk = kp.getPublic();
		//获得私钥
		PrivateKey pvk = kp.getPrivate();
		//建立文件rsapbkey.dat输出流，保存公钥
		FileOutputStream fout = new FileOutputStream("rsapbkey.dat");
		//建立文件对象输出流
		ObjectOutputStream oout = new ObjectOutputStream(fout);
		//向文件rsapbkey.dat输出对象obj
		oout.writeObject(pbk);
		oout.close();
		//建立文件rsapykey.dat输出流，保存私钥
		FileOutputStream foutv= new FileOutputStream("rsapykey.dat");
		//建立文件对象输出流
		ObjectOutputStream ooutb = new ObjectOutputStream(foutv);
		//向文件rsapykey.dat输出对象
		ooutb.writeObject(pvk);
		ooutb.close();
		//获得公钥，计算指数e和模数n
		RSAPublicKey rsapbk = (RSAPublicKey)kp.getPublic();
		BigInteger e = rsapbk.getPublicExponent();
		BigInteger n = rsapbk.getModulus();
		
		String ptext="I have a friend!";
		byte[] pb = ptext.getBytes("UTF8");
		BigInteger m =new BigInteger(pb);
		//执行计算，返回密文
		BigInteger bi = m.modPow(e, n);
		
		System.out.println("bi="+bi);
		//获得私钥参数及解密
		RSAPrivateKey rsapvk = (RSAPrivateKey)kp.getPrivate();
		BigInteger dv = rsapvk.getPrivateExponent();
		BigInteger mv = rsapvk.getModulus();
		//执行计算，即解密
		BigInteger mm = bi.modPow(dv, mv);
		
		byte[] mt = mm.toByteArray();
		for(int i=0;i<mt.length;i++){
			System.out.print((char)mt[i]);
		}
		
		
	}

}