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Java实现RSA加密算法

December 3, 2018 • Read: 908 • 密码学

RSA是一种非对称加密算法,一般采用公钥加密,私钥解密的形式

生成密钥对

首先创建KeyPairGenerator类的对象,用于生成公钥和私钥对

// 生成公钥和私钥对,基于RSA算法生成对象
KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");

然后初始化密钥对的长度,最低长度512位,并且长度不能低于明文的长度

// 初始化密钥大小为1024位
keyPairGen.initialize(1024);

利用keyPairGen对象生成密钥对,保存在KeyPair类中

KeyPair keyPair = keyPairGen.generateKeyPair();

keyPair类中获取公钥和私钥

RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();

加密(encrypt)

protected static byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) {
    if (publicKey != null) {
        try {
            // Cipher负责完成加密或解密工作,基于RSA
            Cipher cipher = Cipher.getInstance(ALGORITHM);

            // 根据公钥,对Cipher对象进行初始化
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);

            // 加密,结果保存进resultBytes,并返回
            byte[] resultBytes = cipher.doFinal(srcBytes);
            return resultBytes;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    return null;
}

解密(decrypt)

protected static byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) {
    if (publicKey != null) {
        try {
            // Cipher负责完成加密或解密工作,基于RSA
            Cipher cipher = Cipher.getInstance("RSA");

            // 根据公钥,对Cipher对象进行初始化
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);

            // 加密,结果保存进resultBytes,并返回
            byte[] resultBytes = cipher.doFinal(srcBytes);
            return resultBytes;
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    return null;
}

完整代码

import java.security.*;
import java.security.interfaces.*;
import javax.crypto.*;

public class RSA {

    private RSAPublicKey publicKey;
    private RSAPrivateKey privateKey;
    private byte[] resultBytes;
    private final static String ALGORITHM = "RSA";

    public RSA() {
        try {
            String message = "你好,我很喜欢加密算法";
            System.out.println("明文是:" + message);
            // 生成公钥和私钥对,基于RSA算法生成对象
            KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(ALGORITHM);

            // 初始化密钥对生成器,密钥大小为1024位
            keyPairGen.initialize(1024);

            // 生成一个密钥对,保存在keyPair中
            KeyPair keyPair = keyPairGen.generateKeyPair();

            // 得到公钥和私钥
            publicKey = (RSAPublicKey) keyPair.getPublic();
            privateKey = (RSAPrivateKey) keyPair.getPrivate();

            // 用公钥加密
            byte[] srcBytes = message.getBytes();
            resultBytes = RSA.encrypt(publicKey, srcBytes);
            String result = new String(resultBytes);
            System.out.println("用公钥加密后密文是:" + result);

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    protected static byte[] encrypt(RSAPublicKey publicKey, byte[] srcBytes) {
        if (publicKey != null) {
            try {
                // Cipher负责完成加密或解密工作,基于RSA
                Cipher cipher = Cipher.getInstance(ALGORITHM);

                // 根据公钥,对Cipher对象进行初始化
                cipher.init(Cipher.ENCRYPT_MODE, publicKey);

                // 加密,结果保存进resultBytes,并返回
                byte[] resultBytes = cipher.doFinal(srcBytes);
                return resultBytes;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    protected byte[] decrypt(RSAPrivateKey privateKey, byte[] encBytes) {
        if (privateKey != null) {
            try {
                Cipher cipher = Cipher.getInstance(ALGORITHM);

                // 根据私钥对Cipher对象进行初始化
                cipher.init(Cipher.DECRYPT_MODE, privateKey);

                // 解密并将结果保存进resultBytes
                byte[] decBytes = cipher.doFinal(encBytes);
                return decBytes;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    public static void main(String[] args) {
        long rsaStart = System.currentTimeMillis();
        RSA rsa = new RSA();
        byte[] decBytes = rsa.decrypt(rsa.privateKey, rsa.resultBytes);
        String dec = new String(decBytes);
        long rsaEnd = System.currentTimeMillis();
        System.out.println("用私钥解密后的结果是:" + dec);
        System.out.println("共计用时:" + (rsaEnd - rsaStart));
    }
}

运行结果见下面的GIF:

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Leave a Comment

已有 3 条评论
  1. 御魂大帝 御魂大帝

    代码写的非常漂亮,想问一下,你这个字体烟花闪烁的特效是怎样弄得呢

    1. mathor mathor

      @御魂大帝可以看这篇文章https://www.moerats.com/archives/372/@(呵呵)

    2. 御魂大帝 御魂大帝

      @mathor谢谢你的回复,@(哈哈)