RSA加解密代码示例

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

public class RSAEncrypt {
    //用于封装随机产生的公钥与私钥
    private static Map<Integer, String> keyMap = new HashMap<Integer, String>();
    public static void main(String[] args) throws Exception {
        /**
         * 在程序中，我们首先利用genKeyPair()函数生成公钥和私钥并将其保存到Map集合中。
         * 然后，基于产生的公钥对明文进行加密。
         * 针对已经已经加密的密文，我们再次使用私钥解密，得到明文
         * */
        //生成公钥和私钥
        genKeyPair();

        //获取当前系统时间
        long start = System.currentTimeMillis();
        int counts = 100000;
        for (int i = 0; i < counts; i++) {
            //加密字符串
            String message = "张三123zhangsan";
            System.out.println("随机生成的公钥为:" + keyMap.get(0) + "
" + "公钥长度:" + keyMap.get(0).length());
            System.out.println("随机生成的私钥为:" + keyMap.get(1) + "
" + "私钥长度:" + keyMap.get(1).length());
            String messageEn = encrypt(message,keyMap.get(0));
            System.out.println(message + "	加密后的字符串为:" + messageEn + "
" + "加密后的字符串长度：" + messageEn.length());
            String messageDe = decrypt(messageEn,keyMap.get(1));
            System.out.println("还原后的字符串为:" + messageDe);
        }
        long end = System.currentTimeMillis();
        System.out.println("10万条数据平均耗时:" + (end - start) / counts + "ms。");
        System.out.println("10万条数据总共耗时:" + (end - start) + "ms。");
    }

    /**
     * 随机生成密钥对
     * @throws NoSuchAlgorithmException
     */
    public static void genKeyPair() throws NoSuchAlgorithmException {
        // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        // 初始化密钥对生成器，密钥大小为96-1024位
        keyPairGen.initialize(1024,new SecureRandom());
        // 生成一个密钥对，保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公钥
        String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
        // 得到私钥字符串
        String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
        // 将公钥和私钥保存到Map
        keyMap.put(0,publicKeyString);  //0表示公钥
        keyMap.put(1,privateKeyString);  //1表示私钥
    }
    /**
     * RSA公钥加密
     *
     * @param str
     *            加密字符串
     * @param publicKey
     *            公钥
     * @return 密文
     * @throws Exception
     *             加密过程中的异常信息
     */
    public static String encrypt( String str, String publicKey ) throws Exception{
        //base64编码的公钥
        byte[] decoded = Base64.decodeBase64(publicKey);
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        //RSA加密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
        return outStr;
    }

    /**
     * RSA私钥解密
     *
     * @param str
     *            加密字符串
     * @param privateKey
     *            私钥
     * @return 铭文
     * @throws Exception
     *             解密过程中的异常信息
     */
    public static String decrypt(String str, String privateKey) throws Exception{
        //64位解码加密后的字符串
        byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
        //base64编码的私钥
        byte[] decoded = Base64.decodeBase64(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        //RSA解密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, priKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }
}