Java 非对称加密RSA应用实现

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import java.util.Base64;
import javax.crypto.Cipher;
 
public class RSACipher {
 
    public static void main(String[] args) throws Exception {
        // 生成密钥对
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
        keyPairGenerator.initialize(2048, new SecureRandom());
        KeyPair keyPair = keyPairGenerator.generateKeyPair();
 
        // 公钥和私钥
        byte[] publicKey = keyPair.getPublic().getEncoded();
        byte[] privateKey = keyPair.getPrivate().getEncoded();
 
        // 编码为Base64
        String publicKeyEncoded = Base64.getEncoder().encodeToString(publicKey);
        String privateKeyEncoded = Base64.getEncoder().encodeToString(privateKey);
 
        System.out.println("公钥:\n" + publicKeyEncoded);
        System.out.println("私钥:\n" + privateKeyEncoded);
 
        // 加密和解密
        String data = "Hello, World!";
        String encryptedData = encrypt(publicKeyEncoded, data);
        String decryptedData = decrypt(privateKeyEncoded, encryptedData);
 
        System.out.println("加密数据:\n" + encryptedData);
        System.out.println("解密数据:\n" + decryptedData);
    }
 
    private static String encrypt(String publicKeyEncoded, String data) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, getPublicKey(publicKeyEncoded));
        byte[] encryptedData = cipher.doFinal(data.getBytes());
        return Base64.getEncoder().encodeToString(encryptedData);
    }
 
    private static String decrypt(String privateKeyEncoded, String encryptedData) throws Exception {
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, getPrivateKey(privateKeyEncoded));
        byte[] decryptedData = cipher.doFinal(Base64.getDecoder().decode(encryptedData));
        return new String(decryptedData);
    }
 
    private static java.security.PublicKey getPublicKey(String publicKeyEncoded) throws Exception {
        byte[] publicKeyDecoded = Base64.getDecoder().decode(publicKeyEncoded);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyDecoded);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        return keyFactory.generatePublic(keySpec);
    }
 
    private static java.security.PrivateKey g