RSA非对称加密和解密方法

RSA公匙和密匙生成方法

package org.markerking;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
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 abstract class RSAKey
...{

    /** *//**
     * 生成2048位的RSA公匙和私匙
     */
    public static void generator(
            String privateKeyFileName) throws Exception
    ...{
        KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
        kpg.initialize(2048);
        KeyPair kp = kpg.generateKeyPair();
        PublicKey puk = kp.getPublic();
        PrivateKey prk = kp.getPrivate();
        FileOutputStream fos1 = new FileOutputStream("publicRSAKey.dat");
        FileOutputStream fos2 = new FileOutputStream(privateKeyFileName);
        ObjectOutputStream oos1 = new ObjectOutputStream(fos1);
        ObjectOutputStream oos2 = new ObjectOutputStream(fos2);
        oos1.writeObject(puk);
        oos2.writeObject(prk);
        oos1.close();
        oos2.close();
        fos1.close();
        fos2.close();
        System.out.println("公匙生成成功!公匙文件为publicRSAKey.dat");
        System.out.println("私匙生成成功!私匙文件为" + privateKeyFileName);
    }

    /** *//**
     * 获取已经生成的公匙
     * 
     * @return RSAPublicKey
     */
    protected static RSAPublicKey getPublicKey(String publicKeyFileName)
            throws Exception
    ...{
        FileInputStream fis = new FileInputStream(publicKeyFileName);
        ObjectInputStream ois = new ObjectInputStream(fis);
        RSAPublicKey rsapuk = (RSAPublicKey) ois.readObject();
        return rsapuk;
    }

    /** *//**
     * 获取已经生成的私匙
     * 
     * @return RSAPrivateKey
     */
    protected static RSAPrivateKey getPrivateKey(String privateKeyFileName)
            throws Exception
    ...{
        FileInputStream fis = new FileInputStream(privateKeyFileName);
        ObjectInputStream ois = new ObjectInputStream(fis);
        RSAPrivateKey psaprk = (RSAPrivateKey) ois.readObject();
        return psaprk;
    }

}

调用方法

package org.markerking;

import java.math.BigInteger;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;

/** *//**
 * RSA非对称式加密与解密
 * 
 * @author MarkerKing
 * @version v1.0
 * @time 2007-2-23 21:19
 */
public class RSAUtil
...{
    /** *//**
     * 加密方法
     * 
     * @param String
     *            需要加密的数据
     * @return String 加密后的数据
     */
    public String S2RSA(String str) throws Exception
    ...{
        // 获得公匙
        RSAPublicKey rsapuk = RSAKey.getPublicKey("publicRSAKey.dat");
        // 获得公匙参数e,n
        BigInteger e = rsapuk.getPublicExponent();
        BigInteger n = rsapuk.getModulus();
        // 转换明文m
        byte[] btext = str.getBytes("GB2312");
        BigInteger m = new BigInteger(btext);
        // 计算密文
        BigInteger c = m.modPow(e, n);
        // 返回
        return c.toString();
    }

    /** *//**
     * 解密方法
     * 
     * @param String
     *            私匙文件
     * @param String
     *            加密后的字符串
     * @return String 解密后的字符串
     */
    public String RSA2S(String fileName, String rsaStr) throws Exception
    ...{
        // 获取私匙
        RSAPrivateKey rsaprk = RSAKey.getPrivateKey(fileName);
        // 获取私匙参数d,n
        BigInteger d = rsaprk.getPrivateExponent();
        BigInteger n = rsaprk.getModulus();
        // 获取密文
        BigInteger c = new BigInteger(rsaStr);
        // 解密计算
        BigInteger m = c.modPow(d, n);
        // 转换成String
        byte[] ctext = m.toByteArray();
        return new String(ctext);
    }

}