基于RSA算法的Java示例代码，展示了如何进行公钥加密、私钥解密、私钥签名和公钥验签。

非堆成加密公私钥使用学习请查看：非堆成加密公私钥使用-CSDN博客

代码实现

package com.chengxuyuan.demo;

import javax.crypto.Cipher;
import java.security.*;
import java.util.Base64;

public class RSADemo {

    public static void main (String[] args) throws Exception {
        // 生成RSA密钥对
        KeyPair keyPair = generateKeyPair ();
        PublicKey publicKey = keyPair.getPublic ();
        PrivateKey privateKey = keyPair.getPrivate ();

        String originalText = "I am a RSA demo!";

        // 公钥加密
        byte[] encryptedText = encrypt (originalText, publicKey);
        System.out.println ("公钥加密内容: " + Base64.getEncoder ().encodeToString (encryptedText));

        // 私钥解密
        String decryptedText = decrypt (encryptedText, privateKey);
        System.out.println ("私钥解密内容: " + decryptedText);

        // 私钥签名
        byte[] signature = sign (originalText, privateKey);
        System.out.println ("私钥签名内容: " + Base64.getEncoder ().encodeToString (signature));

        // 公钥验签
        boolean isVerified = verify (originalText, signature, publicKey);
        System.out.println ("验签 : " + isVerified);
    }

    /**
     * 生成RSA密钥对
     *
     * @return
     * @throws NoSuchAlgorithmException
     */
    public static KeyPair generateKeyPair () throws NoSuchAlgorithmException {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance ("RSA");
        keyPairGenerator.initialize (2048);
        return keyPairGenerator.generateKeyPair ();
    }

    /**
     * 公钥加密
     *
     * @param plainText 文本
     * @param publicKey 公钥
     * @return
     * @throws Exception
     */
    public static byte[] encrypt (String plainText, PublicKey publicKey) throws Exception {
        Cipher cipher = Cipher.getInstance ("RSA");
        cipher.init (Cipher.ENCRYPT_MODE, publicKey);
        return cipher.doFinal (plainText.getBytes ());
    }

    /**
     * 私钥解密
     *
     * @param encryptedText 加密文本
     * @param privateKey    私钥
     * @return
     * @throws Exception
     */
    public static String decrypt (byte[] encryptedText, PrivateKey privateKey) throws Exception {
        Cipher cipher = Cipher.getInstance ("RSA");
        cipher.init (Cipher.DECRYPT_MODE, privateKey);
        byte[] decryptedBytes = cipher.doFinal (encryptedText);
        return new String (decryptedBytes);
    }

    /**
     * 私钥签名
     *
     * @param plainText  文本
     * @param privateKey 私钥
     * @return
     * @throws Exception
     */
    public static byte[] sign (String plainText, PrivateKey privateKey) throws Exception {
        Signature privateSignature = Signature.getInstance ("SHA256withRSA");
        privateSignature.initSign (privateKey);
        privateSignature.update (plainText.getBytes ());
        return privateSignature.sign ();
    }

    /**
     * 公钥验签
     *
     * @param plainText 文本
     * @param signature 签名
     * @param publicKey 公钥
     * @return
     * @throws Exception
     */
    public static boolean verify (String plainText, byte[] signature, PublicKey publicKey) throws Exception {
        Signature publicSignature = Signature.getInstance ("SHA256withRSA");
        publicSignature.initVerify (publicKey);
        publicSignature.update (plainText.getBytes ());
        return publicSignature.verify (signature);
    }
}

运行结果

公钥加密内容: alFHnM0a2eiOvIhyqmByOrMIP/DblmhRnjS6gwSSz/7RN4YsJntwf/JUIHXZxGmCvH2eBHZAx8folkGIZma2MCqkMFPWYW0DkgutDWL/esikRILttHDtAohtfHaNqksR0AKedGVpq8av1bZOxFr1XYfeSNfILYgPbi/UuI4EVC/xFcfwHnEaxKgvPQHV/rbTjAHyz9phKcYpCy/r0EBwJcfEEC4ov7XbnVRmkDSRDzXYi3bwXn5WNKj97ZsN90J5WPRmLZPcD6KA4fFv/FklI9wB0BEWnFRPcfG9Q9w8PBc1Kmb6GGaSJ329ZxI6TQ4fpKuggpN5ejIACDNPk31AAw==
私钥解密内容: I am a RSA demo!
私钥签名内容: etp/Cf3tzAZqVOAqr5GMrOVnvR18hCMWNjGuTz41nqyu4iU5JxHZEW/8Fh0K4AW07qEQveRxNVhiXAKOvqai03HAT//ePUnOqJ7YU4qkLer/WSuHCgJkcB0c7w1egNsAr06m+mI9UsU6Q7TM+EWrctiJH6cSm0zfNHkVTq7fq2viGwxsmULto04dEVVP1PyiDL0PsPSTOrZ5rycoK3WoiyG1SLf127cgRjrnb1tt1h+7E3stcYSnGQdWrcpwVXWhNV3etzQaAKwkNyHkhPTXgY9v1S1YR4WLCGVfCRfPwJt91qF3C3T49B7s7ofQavbSWnIrzfVoHkjIF7ZT3c+Nig==
验签 : true