如何从公钥生成私钥

正文

<groupId>joda-time</groupId>
        <artifactId>joda-time</artifactId>
    </dependency>

## 5.所需拷贝工具


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### JwtUtils:

package com.czxy.utils;
import io.jsonwebtoken.Claims;
 import io.jsonwebtoken.JwtBuilder;
 import io.jsonwebtoken.Jwts;
 import io.jsonwebtoken.SignatureAlgorithm;
 import org.apache.commons.beanutils.BeanUtils;
 import org.joda.time.DateTime;import java.beans.BeanInfo;
 import java.beans.IntrospectionException;
 import java.beans.Introspector;
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.InvocationTargetException;
 import java.security.PrivateKey;
 import java.security.PublicKey;/**
• Created by liangtong.
/
 public class JwtUtils {
 /*• 私钥加密token
• @param data 需要加密的数据（载荷内容）
• @param expireMinutes 过期时间，单位：分钟
• @param privateKey 私钥
• @return
 */
 public static String generateToken(Object data, int expireMinutes, PrivateKey privateKey) {
 try {
 //1 获得jwt构建对象
 JwtBuilder jwtBuilder = Jwts.builder();
 //2 设置数据
 if( data == null ) {
 throw new RuntimeException(“数据不能为空”);
 }
 BeanInfo beanInfo = Introspector.getBeanInfo(data.getClass());
 PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
 for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
 // 获得属性名
 String name = propertyDescriptor.getName();
 // 获得属性值
 Object value = propertyDescriptor.getReadMethod().invoke(data);
 if(value != null) {
 jwtBuilder.claim(name,value);
 }
 }
 //3 设置过期时间
 jwtBuilder.setExpiration(DateTime.now().plusMinutes(expireMinutes).toDate());
 //4 设置加密
 jwtBuilder.signWith(SignatureAlgorithm.RS256, privateKey);
 //5 构建
 return jwtBuilder.compact();
 } catch (Exception e) {
 throw new RuntimeException(e);
 }
 }/**
• 通过公钥解析token
• @param token 需要解析的数据
• @param publicKey 公钥
• @param beanClass 封装的JavaBean
• @return
• @throws Exception
 */
 public static T getObjectFromToken(String token, PublicKey publicKey,Class beanClass) throws Exception {
 //1 获得解析后内容
 Claims body = Jwts.parser().setSigningKey(publicKey).parseClaimsJws(token).getBody();
 //2 将内容封装到对象JavaBean
 T bean = beanClass.newInstance();
 BeanInfo beanInfo = Introspector.getBeanInfo(beanClass);
 PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
 for (PropertyDescriptor propertyDescriptor : propertyDescriptors) {
 // 获得属性名
 String name = propertyDescriptor.getName();
 // 通过属性名，获得对应解析的数据
 Object value = body.get(name);
 if(value != null) {
 // 将获得的数据封装到对应的JavaBean中
 BeanUtils.setProperty(bean,name,value);
 }
 }
 return bean;
 }
 }

### RsaUtils:

package com.czxy.utils;
import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.security.*;
 import java.security.spec.PKCS8EncodedKeySpec;
 import java.security.spec.X509EncodedKeySpec;/**
• Created by liangtong.
 */
 public class RsaUtils {
/**• 从文件中读取公钥
• 
• @param filename 公钥保存路径，相对于classpath
• @return 公钥对象
• @throws Exception
 */
 public static PublicKey getPublicKey(String filename) throws Exception {
 byte[] bytes = readFile(filename);
 return getPublicKey(bytes);
 }/**
• 从文件中读取密钥
• 
• @param filename 私钥保存路径，相对于classpath
• @return 私钥对象
• @throws Exception
 */
 public static PrivateKey getPrivateKey(String filename) throws Exception {
 byte[] bytes = readFile(filename);
 return getPrivateKey(bytes);
 }/**
• 获取公钥
• 
• @param bytes 公钥的字节形式
• @return
• @throws Exception
 */
 public static PublicKey getPublicKey(byte[] bytes) throws Exception {
 X509EncodedKeySpec spec = new X509EncodedKeySpec(bytes);
 KeyFactory factory = KeyFactory.getInstance(“RSA”);
 return factory.generatePublic(spec);
 }/**
• 获取密钥
• 
• @param bytes 私钥的字节形式
• @return
• @throws Exception
 */
 public static PrivateKey getPrivateKey(byte[] bytes) throws Exception {
 PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(bytes);
 KeyFactory factory = KeyFactory.getInstance(“RSA”);
 return factory.generatePrivate(spec);
 }/**
• 根据密文，生存rsa公钥和私钥,并写入指定文件
• 
• @param publicKeyFilename 公钥文件路径
• @param privateKeyFilename 私钥文件路径
• @param secret 生成密钥的密文
• @throws Exception
 */
 public static void generateKey(String publicKeyFilename, String privateKeyFilename, String secret) throws Exception {
 KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(“RSA”);
 SecureRandom secureRandom = new SecureRandom(secret.getBytes());
 keyPairGenerator.initialize(1024, secureRandom);
 KeyPair keyPair = keyPairGenerator.genKeyPair();
 // 获取公钥并写出
 byte[] publicKeyBytes = keyPair.getPublic().getEncoded();
 writeFile(publicKeyFilename, publicKeyBytes);
 // 获取私钥并写出
 byte[] privateKeyBytes = keyPair.getPrivate().getEncoded();
 writeFile(privateKeyFilename, privateKeyBytes);
 }private static byte[] readFile(String fileName) throws Exception {
 return Files.readAllBytes(new File(fileName).toPath());
 }private static void writeFile(String destPath, byte[] bytes) throws IOException {
 File dest = new File(destPath);

//创建父文件夹
 if(!dest.getParentFile().exists()){
     dest.getParentFile().mkdirs();
 }
 //创建需要的文件
 if (!dest.exists()) {
     dest.createNewFile();
 }

 Files.write(dest.toPath(), bytes);

}

}