Java RSA 公钥加密私钥解密

package com.lee.utils;

import java.io.DataInputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.security.KeyFactory;

import java.security.KeyPair;

import java.security.KeyPairGenerator;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.SecureRandom;

import java.security.interfaces.RSAPrivateKey;

import java.security.interfaces.RSAPublicKey;

import java.security.spec.PKCS8EncodedKeySpec;

import java.security.spec.X509EncodedKeySpec;

import java.util.Base64;

import java.util.Date;

import javax.crypto.Cipher;

public class RSAUtil {

    private final static String PUBLIC_KEY_PATH = "c:/publicKeyFile";

    private final static String PRIVATE_KEY_PATH = "c:/privateKeyFile";

    /**

     *生成私钥  公钥

     */

    private static void geration(){

        KeyPairGenerator keyPairGenerator;

        try {

            keyPairGenerator = KeyPairGenerator.getInstance("RSA");

            SecureRandom secureRandom = new SecureRandom(new Date().toString().getBytes());

            keyPairGenerator.initialize(1024, secureRandom);

            KeyPair keyPair = keyPairGenerator.genKeyPair();

            byte[] publicKeyBytes = keyPair.getPublic().getEncoded();

            FileOutputStream fos = new FileOutputStream(PUBLIC_KEY_PATH);

            fos.write(publicKeyBytes);

            fos.close();

            byte[] privateKeyBytes = keyPair.getPrivate().getEncoded();

            fos = new FileOutputStream(PRIVATE_KEY_PATH);

            fos.write(privateKeyBytes);

            fos.close();

        } catch (Exception e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

    /**

     * 获取公钥

     * @param filename

     * @return

     * @throws Exception

     */

    public static PublicKey getPublicKey(String filename) throws Exception {

        File f = new File(filename);

        FileInputStream fis = new FileInputStream(f);

        DataInputStream dis = new DataInputStream(fis);

        byte[] keyBytes = new byte[(int)f.length()];

        dis.readFully(keyBytes);

        dis.close();

        X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);

        KeyFactory kf = KeyFactory.getInstance("RSA");

        return kf.generatePublic(spec);

    } 

    /**

     * 获取私钥

     * @param filename

     * @return

     * @throws Exception

     */

    public static PrivateKey getPrivateKey(String filename)throws Exception {

        File f = new File(filename);

        FileInputStream fis = new FileInputStream(f);

        DataInputStream dis = new DataInputStream(fis);

        byte[] keyBytes = new byte[(int)f.length()];

        dis.readFully(keyBytes);

        dis.close();

        PKCS8EncodedKeySpec spec =new PKCS8EncodedKeySpec(keyBytes);

        KeyFactory kf = KeyFactory.getInstance("RSA");

        return kf.generatePrivate(spec);

      } 

    public static void main(String[] args) {

        geration();

        String input = "!!!hello world!!!";

        RSAPublicKey pubKey;

        RSAPrivateKey privKey;

        byte[] cipherText;

        Cipher cipher;

        try {

            cipher = Cipher.getInstance("RSA");

            pubKey = (RSAPublicKey) getPublicKey(PUBLIC_KEY_PATH);

            privKey = (RSAPrivateKey) getPrivateKey(PRIVATE_KEY_PATH);

            cipher.init(Cipher.ENCRYPT_MODE, pubKey);

            cipherText = cipher.doFinal(input.getBytes());

            //加密后的东西

            System.out.println("cipher: " + new String(cipherText));

            //开始解密

            cipher.init(Cipher.DECRYPT_MODE, privKey);

            byte[] plainText = cipher.doFinal(cipherText);

            System.out.println("publickey: " + Base64.getEncoder().encode(cipherText));

            System.out.println("plain : " + new String(plainText));

        } catch (Exception e1) {

            // TODO Auto-generated catch block

            e1.printStackTrace();

        }

    }

}

Java RSA 公钥加密私钥解密的相关教程结束。