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<?php
namespace OAuth2\Encryption;
use Exception;
use InvalidArgumentException;
/**
* @link https://github.com/F21/jwt
* @author F21
*/
class Jwt implements EncryptionInterface
{
/**
* @param $payload
* @param $key
* @param string $algo
* @return string
*/
public function encode($payload, $key, $algo = 'HS256')
{
$header = $this->generateJwtHeader($payload, $algo);
$segments = array(
$this->urlSafeB64Encode(json_encode($header)),
$this->urlSafeB64Encode(json_encode($payload))
);
$signing_input = implode('.', $segments);
$signature = $this->sign($signing_input, $key, $algo);
$segments[] = $this->urlsafeB64Encode($signature);
return implode('.', $segments);
}
/**
* @param string $jwt
* @param null $key
* @param array|bool $allowedAlgorithms
* @return bool|mixed
*/
public function decode($jwt, $key = null, $allowedAlgorithms = true)
{
if (!strpos($jwt, '.')) {
return false;
}
$tks = explode('.', $jwt);
if (count($tks) != 3) {
return false;
}
list($headb64, $payloadb64, $cryptob64) = $tks;
if (null === ($header = json_decode($this->urlSafeB64Decode($headb64), true))) {
return false;
}
if (null === $payload = json_decode($this->urlSafeB64Decode($payloadb64), true)) {
return false;
}
$sig = $this->urlSafeB64Decode($cryptob64);
if ((bool) $allowedAlgorithms) {
if (!isset($header['alg'])) {
return false;
}
// check if bool arg supplied here to maintain BC
if (is_array($allowedAlgorithms) && !in_array($header['alg'], $allowedAlgorithms)) {
return false;
}
if (!$this->verifySignature($sig, "$headb64.$payloadb64", $key, $header['alg'])) {
return false;
}
}
return $payload;
}
/**
* @param $signature
* @param $input
* @param $key
* @param string $algo
* @return bool
* @throws InvalidArgumentException
*/
private function verifySignature($signature, $input, $key, $algo = 'HS256')
{
// use constants when possible, for HipHop support
switch ($algo) {
case'HS256':
case'HS384':
case'HS512':
return $this->hash_equals(
$this->sign($input, $key, $algo),
$signature
);
case 'RS256':
return openssl_verify($input, $signature, $key, defined('OPENSSL_ALGO_SHA256') ? OPENSSL_ALGO_SHA256 : 'sha256') === 1;
case 'RS384':
return @openssl_verify($input, $signature, $key, defined('OPENSSL_ALGO_SHA384') ? OPENSSL_ALGO_SHA384 : 'sha384') === 1;
case 'RS512':
return @openssl_verify($input, $signature, $key, defined('OPENSSL_ALGO_SHA512') ? OPENSSL_ALGO_SHA512 : 'sha512') === 1;
default:
throw new InvalidArgumentException("Unsupported or invalid signing algorithm.");
}
}
/**
* @param $input
* @param $key
* @param string $algo
* @return string
* @throws Exception
*/
private function sign($input, $key, $algo = 'HS256')
{
switch ($algo) {
case 'HS256':
return hash_hmac('sha256', $input, $key, true);
case 'HS384':
return hash_hmac('sha384', $input, $key, true);
case 'HS512':
return hash_hmac('sha512', $input, $key, true);
case 'RS256':
return $this->generateRSASignature($input, $key, defined('OPENSSL_ALGO_SHA256') ? OPENSSL_ALGO_SHA256 : 'sha256');
case 'RS384':
return $this->generateRSASignature($input, $key, defined('OPENSSL_ALGO_SHA384') ? OPENSSL_ALGO_SHA384 : 'sha384');
case 'RS512':
return $this->generateRSASignature($input, $key, defined('OPENSSL_ALGO_SHA512') ? OPENSSL_ALGO_SHA512 : 'sha512');
default:
throw new Exception("Unsupported or invalid signing algorithm.");
}
}
/**
* @param $input
* @param $key
* @param string $algo
* @return mixed
* @throws Exception
*/
private function generateRSASignature($input, $key, $algo)
{
if (!openssl_sign($input, $signature, $key, $algo)) {
throw new Exception("Unable to sign data.");
}
return $signature;
}
/**
* @param string $data
* @return string
*/
public function urlSafeB64Encode($data)
{
$b64 = base64_encode($data);
$b64 = str_replace(array('+', '/', "\r", "\n", '='),
array('-', '_'),
$b64);
return $b64;
}
/**
* @param string $b64
* @return mixed|string
*/
public function urlSafeB64Decode($b64)
{
$b64 = str_replace(array('-', '_'),
array('+', '/'),
$b64);
return base64_decode($b64);
}
/**
* Override to create a custom header
*/
protected function generateJwtHeader($payload, $algorithm)
{
return array(
'typ' => 'JWT',
'alg' => $algorithm,
);
}
/**
* @param string $a
* @param string $b
* @return bool
*/
protected function hash_equals($a, $b)
{
if (function_exists('hash_equals')) {
return hash_equals($a, $b);
}
$diff = strlen($a) ^ strlen($b);
for ($i = 0; $i < strlen($a) && $i < strlen($b); $i++) {
$diff |= ord($a[$i]) ^ ord($b[$i]);
}
return $diff === 0;
}
}
|
