加密算法---RSA 非对称加密原理及使用

缺乏、安全感 2023-09-24 20:53 124阅读 0赞

### 加密算法---RSA 非对称加密原理及使用 ###

*  一 非对称加密原理介绍
 *  二 加密解密测试
 *   *  2.1 加密解密工具类
     *  2.2 测试

# 一 非对称加密原理介绍 #

非对称加密算法中，有两个密钥：公钥和私钥。它们是一对，如果用公钥进行加密，只有用对应的私钥才能解密；如果用私钥进行加密，只有用对应的公钥才能解密。  
    非对称加密算法实现机密信息的交换过程为：甲方生成一对密钥并将其中一个作为公钥向其他方公开；得到该公钥的乙方使用该密钥对机密信息进行加密后发送给甲方；甲方再用自己的另一个专用密钥对加密后的信息进行解密。  
    最有名的非对称加密算法当属 RSA 了，本文将对 RSA 算法的加/解密过程进行详细剖析。  
    非对称加密拥有两把密钥。  
      
[RSA —— 经典的非对称加密算法][RSA _]

# 二 加密解密测试 #

## 2.1 加密解密工具类 ##

import lombok.extern.slf4j.Slf4j;
    
    import javax.crypto.Cipher;
    import javax.crypto.KeyGenerator;
    import javax.crypto.SecretKey;
    import javax.crypto.SecretKeyFactory;
    import javax.crypto.spec.DESKeySpec;
    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;
    
    @Slf4j
    public class EncryptUtils {
        
    
        /**
         * sha 加密
         *
         * @param str
         * @return
         */
        public static String sha(String str) {
        
            String sha256Str = "";
    
            try {
        
                MessageDigest sha256Deget = MessageDigest.getInstance("SHA-256");
                byte[] sha256Encode = sha256Deget.digest(str.getBytes());
                sha256Str = ByteToHexStr(sha256Encode);
            } catch (Exception e) {
        
                log.info("FRLOG:SHA256加密异常:：", e.getMessage());
            }
    
            return sha256Str;
        }
    
        /**
         * byte数组转16进制字符串
         *
         * @param bytes
         * @return
         */
        private static String ByteToHexStr(byte[] bytes) {
        
            String hexStr = "";
    
            for (int i = 0; i < bytes.length; i++) {
        
                int temp = bytes[i] & 0xff;
                String tempHex = Integer.toHexString(temp);
                if (tempHex.length() < 2) {
        
                    hexStr += "0" + tempHex;
                } else {
        
                    hexStr += tempHex;
                }
            }
    
            return hexStr;
        }
    /**--------------------------对称加密aes----------------------------------*/
        /**
         * aes 加密
         *
         * @param str
         * @param privateKey
         * @return
         */
        public static String aesEncrypt(String str, String privateKey) {
        
            try {
        
                // 生成密钥对象
                SecretKey secKey = generateAesKey(privateKey.getBytes());
    
                // 获取 AES 密码器
                Cipher cipher = Cipher.getInstance("AES");
                // 初始化密码器（加密模型）
                cipher.init(Cipher.ENCRYPT_MODE, secKey);
    
                // 加密数据, 返回密文
                byte[] cipherBytes = cipher.doFinal(str.getBytes());
    //            return new BASE64Encoder().encodeBuffer(cipherBytes);
                return Base64.getEncoder().encodeToString(cipherBytes);
            } catch (Throwable e) {
        
                log.info("aes 加密异常", e.getMessage());
            }
    
            return null;
        }
    
    
        /**
         * aes 解密
         *
         * @param str
         * @param privateKey
         * @return
         */
        public static String aesDecrypt(String str, String privateKey) {
        
            try {
        
                // 生成密钥对象
                SecretKey secKey = generateAesKey(privateKey.getBytes());
    
                // 获取 AES 密码器
                Cipher cipher = Cipher.getInstance("AES");
                // 初始化密码器（加密模型）
                cipher.init(Cipher.DECRYPT_MODE, secKey);
                byte[] decode = Base64.getDecoder().decode(str);
                // 加密数据, 返回密文
                byte[] cipherBytes = cipher.doFinal(decode);
                return new String(cipherBytes);
            } catch (Throwable e) {
        
                log.info("aes 解密异常 ", e.getMessage());
            }
    
            return null;
        }
    
        /**
         * 生成密钥对象
         */
        private static SecretKey generateAesKey(byte[] key) throws Exception {
        
            // 创建安全随机数生成器
            SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
            // 设置 密钥key的字节数组 作为安全随机数生成器的种子
            random.setSeed(key);
    
            // 创建 AES算法生成器
            KeyGenerator gen = KeyGenerator.getInstance("AES");
            // 初始化算法生成器
            gen.init(128, random);
    
            // 生成 AES密钥对象, 也可以直接创建密钥对象: return new SecretKeySpec(key, ALGORITHM);
            return gen.generateKey();
        }
    /**-------------------------- base64加密 ----------------------------------*/
        /**
         * base64加密
         *
         * @param key
         * @return
         */
        public static String base64Encode(byte[] key) {
        
            String result = Base64.getEncoder().encodeToString(key);
            return result;
        }
    
    
        /**
         * base64解密
         *
         * @param key
         * @return
         */
        public static byte[] base64DecodeB(String key) {
        
            byte[] result = null;
            result = Base64.getDecoder().decode(key);
            return result;
        }
    
        /**
         * 是否被base64加密过
         *
         * @param str
         * @return
         */
        public static boolean isBase64(String str) {
        
            if (str == null || str.trim().length() == 0) {
        
                return false;
            } else {
        
                if (str.length() % 4 != 0) {
        
                    return false;
                }
    
                char[] strChars = str.toCharArray();
    
                for (char c : strChars) {
        
                    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '+' || c == '/' || c == '=') {
        
                        continue;
                    } else {
        
                        return false;
                    }
                }
    
                return true;
            }
        }
    /**-------------------------- 对称加密des ----------------------------------*/
        /**
         * des加密
         *
         * @param datasource
         * @param password
         * @return
         */
        public static String desEncrypt(String datasource, String password) {
        
            try {
        
                SecureRandom random = new SecureRandom();
                DESKeySpec desKey = new DESKeySpec(password.getBytes());
                // 创建一个密匙工厂，然后用它把DESKeySpec转换成
                SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
                SecretKey securekey = keyFactory.generateSecret(desKey);
                // Cipher对象实际完成加密操作
                Cipher cipher = Cipher.getInstance("DES");
                // 用密匙初始化Cipher对象
                cipher.init(Cipher.ENCRYPT_MODE, securekey, random);
                // 现在，获取数据并加密
                // 正式执行加密操作
                return base64Encode(cipher.doFinal(datasource.getBytes()));
            } catch (Throwable e) {
        
                log.info("des 加密异常", e.getMessage());
            }
    
            return null;
        }
    
        /**
         * des 解密
         *
         * @param src
         * @param password
         * @return
         * @throws Exception
         */
        public static String desDecrypt(String src, String password) {
        
            try {
        
                // DES算法要求有一个可信任的随机数源
                SecureRandom random = new SecureRandom();
                // 创建一个DESKeySpec对象
                DESKeySpec desKey = new DESKeySpec(password.getBytes("UTF-8"));
                // 创建一个密匙工厂
                SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
                // 将DESKeySpec对象转换成SecretKey对象
                SecretKey securekey = keyFactory.generateSecret(desKey);
                // Cipher对象实际完成解密操作
                Cipher cipher = Cipher.getInstance("DES");
                // 用密匙初始化Cipher对象
                cipher.init(Cipher.DECRYPT_MODE, securekey, random);
                // 真正开始解密操作
                return new String(cipher.doFinal(base64DecodeB(src)));
            } catch (Throwable e) {
        
                log.info("des 解密异常", e.getMessage());
            }
            return null;
        }
    /**-------------------------- 非对称加密RSA ----------------------------------*/
        /**
         * 随机生成RSA密钥对
         *
         * @return privateKey, publicKey
         * @throws NoSuchAlgorithmException
         */
        public static Map<String, String> genRSAKeyPair() throws NoSuchAlgorithmException {
        
            // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
            KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
            // 初始化密钥对生成器，密钥大小为96-1024位
            keyPairGen.initialize(1024, new SecureRandom());
            // 生成一个密钥对，保存在keyPair中
            KeyPair keyPair = keyPairGen.generateKeyPair();
            // 得到私钥
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
            // 得到公钥
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
            String publicKeyString = base64Encode(publicKey.getEncoded());
            // 得到私钥字符串
            String privateKeyString = base64Encode(privateKey.getEncoded());
            // 将公钥和私钥保存到Map
            Map<String, String> result = new HashMap<String, String>();
            result.put("publicKey", publicKeyString.replaceAll("\n", "").replace("\r", "").trim());
            result.put("privateKey", privateKeyString.replaceAll("\n", "").replace("\r", "").trim());
    
            return result;
        }
    
        /**
         * rsa 加密
         *
         * @param str
         * @param publicKey
         * @return
         * @throws Exception
         */
        public static String rsaEncrypt(String str, String publicKey) throws Exception {
        
            //base64编码的公钥
            byte[] decoded = base64DecodeB(publicKey);
            RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
            //RSA加密
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.ENCRYPT_MODE, pubKey);
            String outStr = base64Encode(cipher.doFinal(str.getBytes("UTF-8")));
            return outStr;
        }
    
        /**
         * rsa解密
         *
         * @param str
         * @param privateKey
         * @return
         * @throws Exception
         */
        public static String rsaDecrypt(String str, String privateKey) throws Exception {
        
            //64位解码加密后的字符串
            byte[] inputByte = base64DecodeB(str);
            //base64编码的私钥
            byte[] decoded = base64DecodeB(privateKey);
            RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
            //RSA解密
            Cipher cipher = Cipher.getInstance("RSA");
            cipher.init(Cipher.DECRYPT_MODE, priKey);
            String outStr = new String(cipher.doFinal(inputByte));
            return outStr;
        }
    
    }

## 2.2 测试 ##

1、生成公钥私钥  
2、用公钥加密、私钥解密

@Test
        void rsaTest() throws Exception {
            //生成公钥私钥
            Map<String, String> keys = EncryptUtils.genRSAKeyPair();
            String publicKey = keys.get("publicKey");
            String privateKey = keys.get("privateKey");
            System.out.println(publicKey);
            System.out.println(privateKey);
    
    
            Map<String, java.io.Serializable> map = new HashMap<>(2);
            map.put("username", "xiamaofa");
            map.put("timestamp", 111111111);
            //公钥加密
            String encrypt = EncryptUtils.rsaEncrypt(map.toString(), publicKey);
            //私钥解密
            String decrypt = EncryptUtils.rsaDecrypt(encrypt, privateKey);
            System.out.println(encrypt);
            System.out.println(decrypt);
    
        }

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    {username=xiamaofa, timestamp=111111111}

[RSA _]: https://zhuanlan.zhihu.com/p/450180396