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);


    }




}