package com.kaishengit.security;

import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import org.apache.commons.codec.binary.Base64;

/**
 * 不对称加密帮助类
 * @author kdj
 * 创建时间:2018年4月13日
 */
public class AsymmetricUtil {

    public static void main(String[] args) {
        try {
            String securityStr = "要加密的字符串！！！";
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            //公钥和私钥
            RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
            RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
            
            
            //生成秘钥的字符串
            String rsaPublicKeyStr = Base64.encodeBase64String(rsaPublicKey.getEncoded());
            String rsaPrivateKeyStr = Base64.encodeBase64String(rsaPrivateKey.getEncoded());
            
            //------私钥加密，公钥解密
            String encodeStr = RSAEncodeForPrivate(rsaPrivateKeyStr, securityStr);
            System.out.println("私钥加密:"+encodeStr);
            System.out.println("公钥解密:"+RSADecodeForPublic(rsaPublicKeyStr, encodeStr));
            
            
            //------公钥加密，私钥解密
            encodeStr = RSAEncodeForPublic(rsaPublicKeyStr, securityStr);
            System.out.println("公钥加密:"+encodeStr);
            System.out.println("私钥解密:"+RSADecodeForPrivate(rsaPrivateKeyStr, encodeStr));
        } catch (Exception e) {
            e.printStackTrace();
        }
        
    }
    
    /**
     * 私钥加密
     * @param key 私钥
     * @param securityStr 要加密的字符串
     * @return
     * @throws Exception 
     */
    public static String RSAEncodeForPrivate(String key,String securityStr) throws Exception{
        byte[] rsaPrivateKeyByte = Base64.decodeBase64(key);
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKeyByte);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(securityStr.getBytes());
        String resultStr = Base64.encodeBase64String(result);
        return resultStr;
    }
    
    /**
     * 公钥解密
     * @param key 公钥
     * @param securityStr 加密的字符串
     * @return
     */
    public static String RSADecodeForPublic(String key,String securityStr) throws Exception{
        byte[] rsaPublicKeyByte = Base64.decodeBase64(key);
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKeyByte);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(Base64.decodeBase64(securityStr));
        String resultStr = new String(result);
        return resultStr;
    }
    
    
    
    
    
    
    
    /**
     * 公钥加密
     * @param key 公钥
     * @param securityStr 加密的字符串
     * @return
     */
    public static String RSAEncodeForPublic(String key,String securityStr) throws Exception{
        byte[] rsaPublicKeyByte = Base64.decodeBase64(key);
        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKeyByte);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] result = cipher.doFinal(securityStr.getBytes());
        return Base64.encodeBase64String(result);
    }
    
    
    /**
     * 私钥解密
     * @param key 私钥
     * @param securityStr 要加密的字符串
     * @return
     * @throws Exception 
     */
    public static String RSADecodeForPrivate(String key,String securityStr) throws Exception{
        byte[] rsaPrivateKeyByte = Base64.decodeBase64(key);
        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKeyByte);
        KeyFactory keyFactory = KeyFactory.getInstance("RSA");
        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, privateKey);
        byte[] result = cipher.doFinal(Base64.decodeBase64(securityStr));
        return new String(result);
    }
    
    
}