What is JWT
JWT is the abbreviation of json web token. It encrypts user information into the token, and the server does not store any user information. The server verifies the correctness of the token by using the stored key, and passes verification as long as it is correct. Token-based authentication can replace the traditional cookie+session authentication method.
JWT consists of three parts: header.payload.signature
header part:
{
"alg": "HS256",
"typ": "JWT"
}
The corresponding base64UrlEncode encoding is: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9
Description: This field is in json format. The alg field specifies the algorithm for generating the signature, the default value is HS256, and the default value of typ is JWT
The payload part:
{
"sub": "1234567890",
"name": "John Doe",
"iat": 1516239022
}
The corresponding base64UrlEncode encoding is: eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ
Description: This field is in json format, which indicates that the data of the user identity can be self-defined, which is very flexible. The user that sub faces, name name, iat issuance time. For example, the customizable examples are as follows:
{
"iss": "admin", //该JWT的签发者
"iat": 1535967430, //签发时间
"exp": 1535974630, //过期时间
"nbf": 1535967430, //该时间之前不接收处理该Token
"sub": "www.admin.com", //面向的用户
"jti": "9f10e796726e332cec401c569969e13e" //该Token唯一标识
}
signature part:
HMACSHA256(
base64UrlEncode(header) + "." +
base64UrlEncode(payload),
123456
)
The corresponding signature is: keH6T3x1z7mmhKL1T3r9sQdAxxdzB6siemGMr_6ZOwU
The resulting JWT Token is (header.payload.signature): eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.keH6T3x1z7mmhKL1T3r9sQdAxxdzB6siemGMr_6ZOwU
Description: After coding header and payload for base64UrlEncode splicing. Use the key (here 123456) to sign the HS256 algorithm.
JWT use process
- First login: the user logs in for the first time, enter the user name and password
- Password verification: the server takes out the user name and password from the database for verification
- Generate JWT: The server-side verification is passed, and the JWT is generated according to the information returned from the database and preset rules
- Return JWT: Return JWT in the HTTP RESPONSE of the server
- Request with JWT: The client initiates a request in the future, HTTP REQUEST
- The Authorizatio field in the HEADER must have a value, which is JWT
- Server authentication JWT
How PHP implements JWT
The author uses PHP 7.0.31, no nonsense, directly upload the code, create a new jwt.php, copy and paste as follows:
<?php
/**
* PHP实现jwt
*/
class Jwt {
//头部
private static $header=array(
'alg'=>'HS256', //生成signature的算法
'typ'=>'JWT' //类型
);
//使用HMAC生成信息摘要时所使用的密钥
private static $key='123456';
/**
* 获取jwt token
* @param array $payload jwt载荷 格式如下非必须
* [
* 'iss'=>'jwt_admin', //该JWT的签发者
* 'iat'=>time(), //签发时间
* 'exp'=>time()+7200, //过期时间
* 'nbf'=>time()+60, //该时间之前不接收处理该Token
* 'sub'=>'www.admin.com', //面向的用户
* 'jti'=>md5(uniqid('JWT').time()) //该Token唯一标识
* ]
* @return bool|string
*/
public static function getToken(array $payload)
{
if(is_array($payload))
{
$base64header=self::base64UrlEncode(json_encode(self::$header,JSON_UNESCAPED_UNICODE));
$base64payload=self::base64UrlEncode(json_encode($payload,JSON_UNESCAPED_UNICODE));
$token=$base64header.'.'.$base64payload.'.'.self::signature($base64header.'.'.$base64payload,self::$key,self::$header['alg']);
return $token;
}else{
return false;
}
}
/**
* 验证token是否有效,默认验证exp,nbf,iat时间
* @param string $Token 需要验证的token
* @return bool|string
*/
public static function verifyToken(string $Token)
{
$tokens = explode('.', $Token);
if (count($tokens) != 3)
return false;
list($base64header, $base64payload, $sign) = $tokens;
//获取jwt算法
$base64decodeheader = json_decode(self::base64UrlDecode($base64header), JSON_OBJECT_AS_ARRAY);
if (empty($base64decodeheader['alg']))
return false;
//签名验证
if (self::signature($base64header . '.' . $base64payload, self::$key, $base64decodeheader['alg']) !== $sign)
return false;
$payload = json_decode(self::base64UrlDecode($base64payload), JSON_OBJECT_AS_ARRAY);
//签发时间大于当前服务器时间验证失败
if (isset($payload['iat']) && $payload['iat'] > time())
return false;
//过期时间小宇当前服务器时间验证失败
if (isset($payload['exp']) && $payload['exp'] < time())
return false;
//该nbf时间之前不接收处理该Token
if (isset($payload['nbf']) && $payload['nbf'] > time())
return false;
return $payload;
}
/**
* base64UrlEncode https://jwt.io/ 中base64UrlEncode编码实现
* @param string $input 需要编码的字符串
* @return string
*/
private static function base64UrlEncode(string $input)
{
return str_replace('=', '', strtr(base64_encode($input), '+/', '-_'));
}
/**
* base64UrlEncode https://jwt.io/ 中base64UrlEncode解码实现
* @param string $input 需要解码的字符串
* @return bool|string
*/
private static function base64UrlDecode(string $input)
{
$remainder = strlen($input) % 4;
if ($remainder) {
$addlen = 4 - $remainder;
$input .= str_repeat('=', $addlen);
}
return base64_decode(strtr($input, '-_', '+/'));
}
/**
* HMACSHA256签名 https://jwt.io/ 中HMACSHA256签名实现
* @param string $input 为base64UrlEncode(header).".".base64UrlEncode(payload)
* @param string $key
* @param string $alg 算法方式
* @return mixed
*/
private static function signature(string $input, string $key, string $alg = 'HS256')
{
$alg_config=array(
'HS256'=>'sha256'
);
return self::base64UrlEncode(hash_hmac($alg_config[$alg], $input, $key,true));
}
}
//***********测试和官网是否匹配begin****************************
$payload=array('sub'=>'1234567890','name'=>'John Doe','iat'=>1516239022);
$jwt=new Jwt;
$token=$jwt->getToken($payload);
echo "<pre>";
echo $token;
//对token进行验证签名
$getPayload=$jwt->verifyToken($token);
echo "<br><br>";
var_dump($getPayload);
echo "<br><br>";
//测试和官网是否匹配end
//自己使用测试begin
$payload_test=array('iss'=>'admin','iat'=>time(),'exp'=>time()+7200,'nbf'=>time(),'sub'=>'www.admin.com','jti'=>md5(uniqid('JWT').time()));;
$token_test=Jwt::getToken($payload_test);
echo "<pre>";
echo $token_test;
//对token进行验证签名
$getPayload_test=Jwt::verifyToken($token_test);
echo "<br><br>";
var_dump($getPayload_test);
echo "<br><br>";
//自己使用时候end