RSA算法

package com.zzq.rsa;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStreamWriter;
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;

public class RSAUtil {

	/**
	 * @param args
	 */
	public static void main(String[] args) {

		String s = "zhuzhiqiang"; 
		createPublicPrivateKey();
		encryption(s);
		decrypt();
	}

	public static void createPublicPrivateKey() {
		
		try {
			KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
			kpg.initialize(1024);
			KeyPair kp = kpg.genKeyPair();
			
			PublicKey pbKey = kp.getPublic();
			PrivateKey prKey = kp.getPrivate();
			
			ObjectOutputStream oos1 = new ObjectOutputStream(new FileOutputStream("RSA_pub_key.dat"));
			ObjectOutputStream oos2 = new ObjectOutputStream(new FileOutputStream("RSA_pri_key.dat"));
			
			oos1.writeObject(pbKey);
			oos2.writeObject(prKey);
			
			oos1.close();
			oos2.close();
		} catch (Exception e) {
			e.printStackTrace();
			throw new RuntimeException("生成钥匙失败!");
		}
	}
	
	public static void encryption(String content) {
		
		try {
			ObjectInputStream ois = new ObjectInputStream(new FileInputStream("RSA_pub_key.dat"));
			RSAPublicKey pbk = (RSAPublicKey)ois.readObject();
			BigInteger e = pbk.getPublicExponent();
			BigInteger n = pbk.getModulus();
			
			System.out.println("e=" + e);
			System.out.println("n=" + n);
			
			byte[] text = content.getBytes("UTF-8");
//			System.out.println("text" + text.toString());
			
			BigInteger m = new BigInteger(text);
			System.out.println("text=" + m);
			
			BigInteger c = m.modPow(e, n);
			
			System.out.println("c=" + c);
			
			String s = c.toString();
			
			BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("enc_rsa.dat")));
			bw.write(s, 0, s.length());
			bw.close();
		} catch (Exception e) {
			e.printStackTrace();
			throw new RuntimeException("加密失败!");
		}
	}
	
	public static void decrypt() {
		try {
			BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("enc_rsa.dat")));
			
			String text = br.readLine();
			
			BigInteger c = new BigInteger(text);
			br.close();
			
			ObjectInputStream ois = new ObjectInputStream(new FileInputStream("RSA_pri_key.dat"));
			
			RSAPrivateKey prk = (RSAPrivateKey)ois.readObject();
			ois.close();
			BigInteger d = prk.getPrivateExponent();
			BigInteger n = prk.getModulus();
			
			System.out.println("d=" + d);
			System.out.println("n=" + n);
			
			BigInteger m = c.modPow(d, n);
			
			System.out.println("m=" + m);
			
			byte[] mt = m.toByteArray();
			
			System.out.println(new String(mt, "UTF-8"));
			
		} catch (Exception e) {
			e.printStackTrace();
			throw new RuntimeException("解密失败!");
		}
	}
}