確保bcprov及codec的jar包存在路徑彙總

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import java.security.Security;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.Scanner;

import javax.crypto.Cipher;

import
 
 org.apache.commons.codec.binary.Base64;


public class RSAUtils {

    private static final KeyPair keyPair = initKey();

    private static KeyPair initKey(){
        try {
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
            SecureRandom random = new
 
 SecureRandom();
            KeyPairGenerator generator = KeyPairGenerator.getInstance("RSA", "BC");
            generator.initialize(1024, random);
            return generator.generateKeyPair();
        }catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 生成public key
     * @return
 

     */
    public static String generateBase64PublicKey(){
        RSAPublicKey key = (RSAPublicKey)keyPair.getPublic();
        return new String(Base64.encodeBase64(key.getEncoded()));
    }

    /**
     * 解密
     * @param string
     * @return
     */
    public static String decryptBase64(String string) {
        return new String(decrypt(Base64.decodeBase64(string)));
    }

    private static byte[] decrypt(byte[] string) {
        try {
            Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
            Cipher cipher = Cipher.getInstance("RSA/None/PKCS1Padding", "BC");
            RSAPrivateKey pbk = (RSAPrivateKey)keyPair.getPrivate();
            cipher.init(Cipher.DECRYPT_MODE, pbk);
            byte[] plainText = cipher.doFinal(string);
            return plainText;
        }catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) {
        // 生成public key
        System.out.println(generateBase64PublicKey());

       /*
        js端 加密過程
       var publicKey = ""; //java產生的公鑰
       var encrypt = new JSEncrypt();
       encrypt.setPublicKey(publicKey);
       // 加密
       alert(encrypt.encrypt("hello"));
       */

        // 解密
        Scanner s=new Scanner(System.in);
        String str=s.nextLine();
        System.out.println(decryptBase64(str));
    }

}