package com.geostar.gfstack.cas.util;

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

import javax.crypto.Cipher;

import java.security.*;

import java.security.interfaces.RSAPrivateKey;

import java.security.interfaces.RSAPublicKey;

import java.security.spec.PKCS8EncodedKeySpec;

import java.security.spec.X509EncodedKeySpec;

/**

 * RSA加解密工具类，实现公钥加密私钥解密和私钥解密公钥解密

 */

public class RSAUtils {

    private static final String src = "abcdefghijklmnopqrstuvwxyz";

    public static void main(String[] args) throws Exception {

        System.out.println("\n");

        RSAKeyPair keyPair = generateKeyPair();

        System.out.println("公钥：" + keyPair.getPublicKey());

        System.out.println("私钥：" + keyPair.getPrivateKey());

        System.out.println("\n");

        test1(keyPair, src);

        System.out.println("\n");

        test2(keyPair, src);

        System.out.println("\n");

    }

    /**

     * 公钥加密私钥解密

     */

    private static void test1(RSAKeyPair keyPair, String source) throws Exception {

        System.out.println("***************** 公钥加密私钥解密开始 *****************");

        String text1 = encryptByPublicKey(keyPair.getPublicKey(), source);

        String text2 = decryptByPrivateKey(keyPair.getPrivateKey(), text1);

        System.out.println("加密前：" + source);

        System.out.println("加密后：" + text1);

        System.out.println("解密后：" + text2);

        if (source.equals(text2)) {

            System.out.println("解密字符串和原始字符串一致，解密成功");

        } else {

            System.out.println("解密字符串和原始字符串不一致，解密失败");

        }

        System.out.println("***************** 公钥加密私钥解密结束 *****************");

    }

    /**

     * 私钥加密公钥解密

     *

     * @throws Exception

     */

    private static void test2(RSAKeyPair keyPair, String source) throws Exception {

        System.out.println("***************** 私钥加密公钥解密开始 *****************");

        String text1 = encryptByPrivateKey(keyPair.getPrivateKey(), source);

        String text2 = decryptByPublicKey(keyPair.getPublicKey(), text1);

        System.out.println("加密前：" + source);

        System.out.println("加密后：" + text1);

        System.out.println("解密后：" + text2);

        if (source.equals(text2)) {

            System.out.println("解密字符串和原始字符串一致，解密成功");

        } else {

            System.out.println("解密字符串和原始字符串不一致，解密失败");

        }

        System.out.println("***************** 私钥加密公钥解密结束 *****************");

    }

    /**

     * 公钥解密

     *

     * @param publicKeyText

     * @param text

     * @return

     * @throws Exception

     */

    public static String decryptByPublicKey(String publicKeyText, String text) throws Exception {

        X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));

        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(text));

        return new String(result);

    }

    /**

     * 私钥加密

     *

     * @param privateKeyText

     * @param text

     * @return

     * @throws Exception

     */

    public static String encryptByPrivateKey(String privateKeyText, String text) throws Exception {

        PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));

        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(text.getBytes());

        return Base64.encodeBase64String(result);

    }

    /**

     * 私钥解密

     *

     * @param privateKeyText

     * @param text

     * @return

     * @throws Exception

     */

    public static String decryptByPrivateKey(String privateKeyText, String text) throws Exception {

        PKCS8EncodedKeySpec pkcs8EncodedKeySpec5 = new PKCS8EncodedKeySpec(Base64.decodeBase64(privateKeyText));

        KeyFactory keyFactory = KeyFactory.getInstance("RSA");

        PrivateKey privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec5);

        Cipher cipher = Cipher.getInstance("RSA");

        cipher.init(Cipher.DECRYPT_MODE, privateKey);

        byte[] result = cipher.doFinal(Base64.decodeBase64(text));

        return new String(result);

    }

    /**

     * 公钥加密

     *

     * @param publicKeyText

     * @param text

     * @return

     */

    public static String encryptByPublicKey(String publicKeyText, String text) throws Exception {

        X509EncodedKeySpec x509EncodedKeySpec2 = new X509EncodedKeySpec(Base64.decodeBase64(publicKeyText));

        KeyFactory keyFactory = KeyFactory.getInstance("RSA");

        PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec2);

        Cipher cipher = Cipher.getInstance("RSA");

        cipher.init(Cipher.ENCRYPT_MODE, publicKey);

        byte[] result = cipher.doFinal(text.getBytes());

        return Base64.encodeBase64String(result);

    }

    /**

     * 构建RSA密钥对

     *

     * @return

     * @throws NoSuchAlgorithmException

     */

    public static RSAKeyPair generateKeyPair() throws NoSuchAlgorithmException {

        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");

        keyPairGenerator.initialize(1024);

        KeyPair keyPair = keyPairGenerator.generateKeyPair();

        RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();

        RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();

        String publicKeyString = Base64.encodeBase64String(rsaPublicKey.getEncoded());

        String privateKeyString = Base64.encodeBase64String(rsaPrivateKey.getEncoded());

        RSAKeyPair rsaKeyPair = new RSAKeyPair(publicKeyString, privateKeyString);

        return rsaKeyPair;

    }

    /**

     * RSA密钥对对象

     */

    public static class RSAKeyPair {

        private String publicKey;

        private String privateKey;

        public RSAKeyPair(String publicKey, String privateKey) {

            this.publicKey = publicKey;

            this.privateKey = privateKey;

        }

        public String getPublicKey() {

            return publicKey;

        }

        public String getPrivateKey() {

            return privateKey;

        }

    }

}