RSAUtils工具類

package com.xiaobu.base.util;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.nio.charset.StandardCharsets;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;

/**
 * @author xiaobu
 * @version JDK1.8.0_171
 * @date on  2020/3/3 16:19
 * @description
 */
public class RSAUtils {



    /**
     * RSA最大加密明文大小 2048/8-11
     */
    private static final int MAX_ENCRYPT_BLOCK = 245;

    /**
     * RSA最大解密密文大小 2048/8
     */
    private static final int MAX_DECRYPT_BLOCK = 256;
    //定義加密方式
    public static final String KEY_RSA = "RSA";
    //定義公鑰關鍵詞
    public static final String KEY_RSA_PUBLICKEY = "RSAPublicKey";
    //定義私鑰關鍵詞
    public static final String KEY_RSA_PRIVATEKEY = "RSAPrivateKey";
    //定義簽名算法
    private final static String KEY_RSA_SIGNATURE = "MD5withRSA";

    /**
     * 生成公私密鑰對
     */
    public static Map<String, Object> init() {
        Map<String, Object> map = null;
        try {
            KeyPairGenerator generator = KeyPairGenerator.getInstance(KEY_RSA);
            //設置密鑰對的bit數，越大越安全，但速度減慢，一般使用512或1024
            generator.initialize(2048);
            KeyPair keyPair = generator.generateKeyPair();
            // 獲取公鑰
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
            // 獲取私鑰
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
            // 將密鑰對封裝爲Map
            map = new HashMap<String, Object>();
            map.put(KEY_RSA_PUBLICKEY, publicKey);
            map.put(KEY_RSA_PRIVATEKEY, privateKey);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }

        return map;
    }

    /**
     * 獲取Base64編碼的公鑰字符串
     */
    public static String getPublicKey(Map<String, Object> map) {
        String str = "";
        Key key = (Key) map.get(KEY_RSA_PUBLICKEY);
        str = encryptBase64(key.getEncoded());
        return str;
    }

    /**
     * 獲取Base64編碼的私鑰字符串
     */
    public static String getPrivateKey(Map<String, Object> map) {
        String str = "";
        Key key = (Key) map.get(KEY_RSA_PRIVATEKEY);
        str = encryptBase64(key.getEncoded());
        return str;
    }

    /**
     * BASE64 解碼
     * @param key 需要Base64解碼的字符串
     * @return 字節數組
     */
    public static byte[] decryptBase64(String key) {
        return Base64.getDecoder().decode(key);
    }

    /**
     * BASE64 編碼
     * @param key 需要Base64編碼的字節數組
     * @return 字符串
     */
    public static String encryptBase64(byte[] key) {
        return new String(Base64.getEncoder().encode(key));
    }

    /**
     * 公鑰加密
     */
    public static String encryptByPublic(String encryptingStr, String publicKeyStr){
        try {
            // 將公鑰由字符串轉爲UTF-8格式的字節數組
            byte[] publicKeyBytes = decryptBase64(publicKeyStr);
            // 獲得公鑰
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyBytes);
            // 取得待加密數據
            byte[] data = encryptingStr.getBytes(StandardCharsets.UTF_8);
            KeyFactory factory;
            factory = KeyFactory.getInstance(KEY_RSA);
            PublicKey publicKey = factory.generatePublic(keySpec);
            // 對數據加密
            Cipher cipher = Cipher.getInstance(factory.getAlgorithm());
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            // 返回加密後由Base64編碼的加密信息
            return encryptBase64(cipher.doFinal(data));
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * 私鑰解密
     */
    public static String decryptByPrivate(String encryptedStr, String privateKeyStr){
        try {
            // 對私鑰解密
            byte[] privateKeyBytes = decryptBase64(privateKeyStr);
            // 獲得私鑰
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKeyBytes);
            // 獲得待解密數據
            byte[] data = decryptBase64(encryptedStr);
            KeyFactory factory = KeyFactory.getInstance(KEY_RSA);
            PrivateKey privateKey = factory.generatePrivate(keySpec);
            // 對數據解密
            Cipher cipher = Cipher.getInstance(factory.getAlgorithm());
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            // 返回UTF-8編碼的解密信息
            return new String(cipher.doFinal(data), StandardCharsets.UTF_8);
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * 私鑰加密  如果大於245則分段加密
     */
    public static String encryptByPrivate(String encryptingStr, String privateKeyStr){
        try {
            byte[] privateKeyBytes = decryptBase64(privateKeyStr);
            // 獲得私鑰
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKeyBytes);
            // 取得待加密數據
            byte[] data = encryptingStr.getBytes(StandardCharsets.UTF_8);
            KeyFactory factory = KeyFactory.getInstance(KEY_RSA);
            PrivateKey privateKey = factory.generatePrivate(keySpec);
            // 對數據加密
            Cipher cipher = Cipher.getInstance(factory.getAlgorithm());
            cipher.init(Cipher.ENCRYPT_MODE, privateKey);
            int inputLen = data.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 對數據分段加密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                    cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(data, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_ENCRYPT_BLOCK;
            }
            byte[] encryptedData = out.toByteArray();
            out.close();
            // 返回加密後由Base64編碼的加密信息
            return encryptBase64(encryptedData);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 公鑰解密 如果大於256則分段解密
     */
    public static String decryptByPublic(String encryptedStr, String publicKeyStr){
        try {
            // 對公鑰解密
            byte[] publicKeyBytes = decryptBase64(publicKeyStr);
            // 取得公鑰
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(publicKeyBytes);
            // 取得待加密數據
            byte[] data = decryptBase64(encryptedStr);
            KeyFactory factory = KeyFactory.getInstance(KEY_RSA);
            PublicKey publicKey = factory.generatePublic(keySpec);
            // 對數據解密
            Cipher cipher = Cipher.getInstance(factory.getAlgorithm());
            cipher.init(Cipher.DECRYPT_MODE, publicKey);
            int inputLen = data.length;
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int offSet = 0;
            byte[] cache;
            int i = 0;
            // 對數據分段解密
            while (inputLen - offSet > 0) {
                if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                    cache = cipher.doFinal(data, offSet, MAX_DECRYPT_BLOCK);
                } else {
                    cache = cipher.doFinal(data, offSet, inputLen - offSet);
                }
                out.write(cache, 0, cache.length);
                i++;
                offSet = i * MAX_DECRYPT_BLOCK;
            }
            byte[] decryptedData = out.toByteArray();
            out.close();
            // 返回UTF-8編碼的解密信息
            return new String(decryptedData, StandardCharsets.UTF_8);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 用私鑰對加密數據進行簽名
     */
    public static String sign(String encryptedStr, String privateKey) {
        String str = "";
        try {
            //將私鑰加密數據字符串轉換爲字節數組
            byte[] data = encryptedStr.getBytes();
            // 解密由base64編碼的私鑰
            byte[] bytes = decryptBase64(privateKey);
            // 構造PKCS8EncodedKeySpec對象
            PKCS8EncodedKeySpec pkcs = new PKCS8EncodedKeySpec(bytes);
            // 指定的加密算法
            KeyFactory factory = KeyFactory.getInstance(KEY_RSA);
            // 取私鑰對象
            PrivateKey key = factory.generatePrivate(pkcs);
            // 用私鑰對信息生成數字簽名
            Signature signature = Signature.getInstance(KEY_RSA_SIGNATURE);
            signature.initSign(key);
            signature.update(data);
            str = encryptBase64(signature.sign());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return str;
    }

    /**
     * 校驗數字簽名
     * @return 校驗成功返回true，失敗返回false
     */
    public static boolean verify(String encryptedStr, String publicKey, String sign) {
        boolean flag = false;
        try {
            //將私鑰加密數據字符串轉換爲字節數組
            byte[] data = encryptedStr.getBytes();
            // 解密由base64編碼的公鑰
            byte[] bytes = decryptBase64(publicKey);
            // 構造X509EncodedKeySpec對象
            X509EncodedKeySpec keySpec = new X509EncodedKeySpec(bytes);
            // 指定的加密算法
            KeyFactory factory = KeyFactory.getInstance(KEY_RSA);
            // 取公鑰對象
            PublicKey key = factory.generatePublic(keySpec);
            // 用公鑰驗證數字簽名
            Signature signature = Signature.getInstance(KEY_RSA_SIGNATURE);
            signature.initVerify(key);
            signature.update(data);
            flag = signature.verify(decryptBase64(sign));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return flag;
    }


    /**
     * 功能描述:格式化公私鑰
     *公鑰字符串開頭要加上“-----BEGIN PUBLIC KEY-----\n”，結尾加上“\n-----END PUBLIC KEY-----\n”
     * 私鑰字符串開頭要加上“-----BEGIN RSA PRIVATE KEY-----\n”，結尾加上“\n-----END RSA PRIVATE KEY-----\n”
     * @author xiaobu
     * @date 2020/3/18 16:40
     * @param str 要格式的字符串, flag
     * @param  flag true爲公 false爲私
     * @return java.lang.String
     * @version 1.0
     */
    public static String formatStr(String str,boolean flag){
        StringBuilder sb = new StringBuilder(str);
        for (int i = 0,len=sb.length(); i < len; i++) {
            if(i%64==0){
                sb.insert(i, "\n");
            }
        }
        if(flag){
            sb = new StringBuilder("-----BEGIN PUBLIC KEY-----").append(sb).append("\n-----END PUBLIC KEY-----\n");
        }else {
            sb = new StringBuilder("-----BEGIN RSA PRIVATE KEY-----").append(sb).append("\n-----END RSA PRIVATE KEY-----\n");
        }
        return sb.toString();
    }



    /**
     * 測試方法
     */
    public static void main(String[] args) {
        Map<String, Object> map = new HashMap<String, Object>();
        map = RSAUtils.init();
        String  publicKey= RSAUtils.getPublicKey(map);
        String  privateKey= RSAUtils.getPrivateKey(map);
        System.out.println("publicKey = " + publicKey);
        System.out.println("privateKey = " + privateKey);
        //由前四行代碼獲得公、私密鑰
        //String publicKey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCLNbmKl9/gLn7Bef/xtUkshC1WyrLZLRpXCcFYR1gQi0isWsZBTicC4efBOkkNG3r+1ue0gvtuU/tjREFGf4Y7HaKHGb5tNCOlMNeNjM5YLRwLFqrUSsQyD4rj4eua1ltearr24R0HilnTvnQm6Z/UY0s21vdOUFQBPY0GNAa+0wIDAQAB";
        //String privateKey = "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";
        String str = "你好小布, RSA!";
        // 公鑰加密，私鑰解密
        String enStr1 = RSAUtils.encryptByPublic(str, publicKey);
        System.out.println("公鑰加密後："+enStr1);
        String deStr1 = RSAUtils.decryptByPrivate(enStr1, privateKey);
        System.out.println("私鑰解密後："+deStr1);
        // 私鑰加密，公鑰解密
        String enStr2 = RSAUtils.encryptByPrivate(str, privateKey);
        System.out.println("私鑰加密後："+enStr2);
        String deStr2 = RSAUtils.decryptByPublic(enStr2, publicKey);
        System.out.println("公鑰解密後："+deStr2);
        // 產生簽名
        String sign = sign(enStr2, privateKey);
        System.out.println("簽名:"+sign);
        // 驗證簽名
        boolean status = verify(enStr2, publicKey, sign);
        System.out.println("狀態:"+status);

    }

}