89 lines
2.1 KiB
PHP
89 lines
2.1 KiB
PHP
<?php
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namespace Vn\Web;
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use Exception;
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/**
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* Basic class to encode, decode and verify JWT tokens. It implements the HS256
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* algorithm from the RFC 7519 standard.
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**/
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class Jwt
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{
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/**
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* Creates a new JWT token with the passed $payload and $key.
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*
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* @param {Array} $payload The data to encode
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* @param {string} $key The key used to sign the token
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* @return {string} The new JWT token
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**/
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static function encode ($payload, $key)
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{
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$header = [
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'alg' => 'HS256',
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'typ' => 'JWT'
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];
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$b64Header = self::jsonB64Encode ($header);
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$b64Payload = self::jsonB64Encode ($payload);
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$b64Signature = self::getSignature ($b64Header, $b64Payload, $key);
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return "$b64Header.$b64Payload.$b64Signature";
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}
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/**
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* Validates and extracts the data from a JWT token.
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*
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* @param {Array} $token The JWT token
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* @param {string} $key The key used to validate the token
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* @return {string} The JWT validated and decoded data
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**/
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static function decode ($token, $key)
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{
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$parts = explode ('.', $token);
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if (count($parts) !== 3)
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throw new Exception ('Bad JWT token');
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$b64Header = $parts[0];
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$b64Payload = $parts[1];
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$b64Signature = $parts[2];
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$header = self::jsonB64Decode ($b64Header);
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$payload = self::jsonB64Decode ($b64Payload);
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if ($b64Signature != self::getSignature ($b64Header, $b64Payload, $key))
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throw new Exception ('Bad token signature');
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return $payload;
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}
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static function getSignature ($b64Header, $b64Payload, $key)
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{
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$signature = hash_hmac ('sha256', "$b64Header.$b64Payload", $key, TRUE);
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return self::base64UrlEncode ($signature);
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}
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static function jsonB64Encode ($data)
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{
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return self::base64UrlEncode (json_encode ($data));
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}
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static function jsonB64Decode ($data)
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{
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return json_decode (self::base64UrlDecode ($data), TRUE);
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}
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static function base64UrlEncode ($data)
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{
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return rtrim (strtr (base64_encode ($data), '+/', '-_'), '=');
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}
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static function base64UrlDecode ($data)
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{
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$remainder = strlen ($data) % 4;
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$data = strtr ($data, '-_', '+/');
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return base64_decode (str_pad ($data, $remainder, '=', STR_PAD_RIGHT));
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}
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}
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