JSON Web Tokens的实现原理

{
  "typ":"JWT","alg":"HS256","exp":1491066992916
}

{
  "userid":"123456","iss":"companyName"
}

#!/usr/bin/env python
# coding: utf-8

from itsdangerous import BadTimeSignature,SignatureExpired
from itsdangerous import TimedJSONWebSignatureSerializer as Serializer

APP_SECRET_KEY="secret"
MAX_TOKEN_AGE=1800
token_generator = Serializer(APP_SECRET_KEY,expires_in=MAX_TOKEN_AGE)

def generate_auth_token(userid):
  access_token = token_generator.dumps({"userid":userid})
  return access_token
def verify_token(token):
  try:
    user_auth = token_generator.loads(token)
    print type(token_generator)
  except SignatureExpired as e:
    raise e
  except BadTimeSignature as e:
    raise e
  return user_auth

package api.test.util;

import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import lombok.extern.slf4j.Slf4j;
import net.sf.json.JSONObject;

/**
 * jwt加解密实现
 * 
 * @author zhengsc
 */
@Slf4j
public class TokenUtil {

  private String ISSUER = "companyName"; // 机构

  private String APP_SECRET_KEY = "secret"; // 密钥

  private long MAX_TOKEN_AGE = 1800; // 存活期

  /**
   * 生成userId的accessToken
   * 
   * @param userid
   * @return
   */
  public String generateAccessToken(String userid) {
    JSONObject claims = new JSONObject();
    claims.put("iss",ISSUER);
    claims.put("userid",userid);
    String accessToken = sign(claims,APP_SECRET_KEY);
    return accessToken;
  }

  /**
   * 解密程序返回userid
   * 
   * @param token
   * @return
   */
  public String verifyToken(String token) {
    String userid = "";
    try {
      String[] splitStr = token.split(".");
      String headerAndClaimsStr = splitStr[0] + "." +splitStr[1];
      String veryStr = signHmac256(headerAndClaimsStr,APP_SECRET_KEY);
      // 校验数据是否被篡改
      if (veryStr.equals(splitStr[2])) {
        String header = new String(Base64.decodeBase64(splitStr[0]),"UTF-8");
        JSONObject head = JSONObject.fromObject(header);
        long expire = head.getLong("exp") * 1000L;
        long currentTime = System.currentTimeMillis();
        if (currentTime <= expire){ // 验证accessToken的有效期
          String claims = new String(Base64.decodeBase64(splitStr[1]),"UTF-8");
          JSONObject claim = JSONObject.fromObject(claims);
          userid = (String) claim.get("userid");
        }
      }
    } catch (UnsupportedEncodingException e) {
      log.error(e.getMessage(),e);
    }

    return userid;
  }

  /**
   * 组装加密结果jwt返回
   * 
   * @param claims
   * @param appSecretKey
   * @return
   */
  private String sign(JSONObject claims,String appSecretKey) {
    String headerAndClaimsStr = getHeaderAndClaimsStr(claims);
    String signed256 = signHmac256(headerAndClaimsStr,appSecretKey);
    return headerAndClaimsStr + "." + signed256;
  }

  /**
   * 拼接请求头和声明
   * 
   * @param claims
   * @return
   */
  private String getHeaderAndClaimsStr(JSONObject claims) {
    JSONObject header = new JSONObject();
    header.put("alg","HS256");
    header.put("typ","JWT");
    header.put("exp",System.currentTimeMillis() + MAX_TOKEN_AGE * 1000L);
    String headerStr = header.toString();
    String claimsStr = claims.toString();
    String headerAndClaimsStr = Base64.encodeBase64URLSafeString(headerStr.getBytes()) + "."
        + Base64.encodeBase64URLSafeString(claimsStr.getBytes());
    return headerAndClaimsStr;
  }

  /**
   * 将headerAndClaimsStr用SHA1加密获取sign
   * 
   * @param headerAndClaimsStr
   * @param appSecretKey
   * @return
   */
  private String signHmac256(String headerAndClaimsStr,String appSecretKey) {
    SecretKey key = new SecretKeySpec(appSecretKey.getBytes(),"HmacSHA256");
    String result = null;
    try {
      Mac mac;
      mac = Mac.getInstance(key.getAlgorithm());
      mac.init(key);
      result = Base64.encodeBase64URLSafeString(mac.doFinal(headerAndClaimsStr.getBytes()));
    } catch (NoSuchAlgorithmException | InvalidKeyException e) {
      log.error(e.getMessage(),e);
    }
    return result;
  }

}