MyShaarli/application/api/ApiUtils.php
VirtualTam 7a9daac56d API: fix JWT signature verification
Fixes https://github.com/shaarli/Shaarli/issues/737

Added:
- Base64Url utilities

Fixed:
- use URL-safe Base64 encoding/decoding functions
- use byte representations for HMAC digests
- all JWT parts are Base64Url-encoded

See:
- https://en.wikipedia.org/wiki/JSON_Web_Token
- https://tools.ietf.org/html/rfc7519
- https://scotch.io/tutorials/the-anatomy-of-a-json-web-token
- https://jwt.io/introduction/
- https://en.wikipedia.org/wiki/Base64#URL_applications
- https://secure.php.net/manual/en/function.base64-encode.php#103849

Signed-off-by: VirtualTam <virtualtam@flibidi.net>
2017-01-04 16:59:47 +01:00

49 lines
1.5 KiB
PHP

<?php
namespace Shaarli\Api;
use Shaarli\Base64Url;
use Shaarli\Api\Exceptions\ApiAuthorizationException;
/**
* REST API utilities
*/
class ApiUtils
{
/**
* Validates a JWT token authenticity.
*
* @param string $token JWT token extracted from the headers.
* @param string $secret API secret set in the settings.
*
* @throws ApiAuthorizationException the token is not valid.
*/
public static function validateJwtToken($token, $secret)
{
$parts = explode('.', $token);
if (count($parts) != 3 || strlen($parts[0]) == 0 || strlen($parts[1]) == 0) {
throw new ApiAuthorizationException('Malformed JWT token');
}
$genSign = Base64Url::encode(hash_hmac('sha512', $parts[0] .'.'. $parts[1], $secret, true));
if ($parts[2] != $genSign) {
throw new ApiAuthorizationException('Invalid JWT signature');
}
$header = json_decode(Base64Url::decode($parts[0]));
if ($header === null) {
throw new ApiAuthorizationException('Invalid JWT header');
}
$payload = json_decode(Base64Url::decode($parts[1]));
if ($payload === null) {
throw new ApiAuthorizationException('Invalid JWT payload');
}
if (empty($payload->iat)
|| $payload->iat > time()
|| time() - $payload->iat > ApiMiddleware::$TOKEN_DURATION
) {
throw new ApiAuthorizationException('Invalid JWT issued time');
}
}
}