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

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

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MapMap<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

 @Testvoid 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}