src/Util/LDSignature.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2022, the Friendica project
   4  *
   5  * @license GNU AGPL version 3 or any later version
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU Affero General Public License as
   9  * published by the Free Software Foundation, either version 3 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU Affero General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Affero General Public License
  18  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19  *
  20  */
  21
  22 namespace Friendica\Util;
  23
  24 use Friendica\Core\Logger;
  25 use Friendica\Model\APContact;
  26
  27 /**
  28  * Implements JSON-LD signatures
  29  *
  30  * Ported from Osada: https://framagit.org/macgirvin/osada
  31  */
  32 class LDSignature
  33 {
  34         public static function isSigned($data)
  35         {
  36                 return !empty($data['signature']);
  37         }
  38
  39         public static function getSigner($data)
  40         {
  41                 if (!self::isSigned($data)) {
  42                         return false;
  43                 }
  44
  45                 $actor = JsonLD::fetchElement($data, 'actor', 'id');
  46                 if (empty($actor) || !is_string($actor)) {
  47                         return false;
  48                 }
  49
  50                 $profile = APContact::getByURL($actor);
  51                 if (empty($profile['pubkey'])) {
  52                         return false;
  53                 }
  54                 $pubkey = $profile['pubkey'];
  55
  56                 $ohash = self::hash(self::signableOptions($data['signature']));
  57                 $dhash = self::hash(self::signableData($data));
  58
  59                 $x = Crypto::rsaVerify($ohash . $dhash, base64_decode($data['signature']['signatureValue']), $pubkey);
  60                 Logger::notice('LD-verify', ['verified' => (int)$x, 'actor' => $profile['url']]);
  61
  62                 if (empty($x)) {
  63                         return false;
  64                 } else {
  65                         return $actor;
  66                 }
  67         }
  68
  69         public static function sign($data, $owner)
  70         {
  71                 $options = [
  72                         'type' => 'RsaSignature2017',
  73                         'nonce' => Strings::getRandomHex(64),
  74                         'creator' => $owner['url'] . '#main-key',
  75                         'created' => DateTimeFormat::utcNow(DateTimeFormat::ATOM)
  76                 ];
  77
  78                 $ohash = self::hash(self::signableOptions($options));
  79                 $dhash = self::hash(self::signableData($data));
  80                 $options['signatureValue'] = base64_encode(Crypto::rsaSign($ohash . $dhash, $owner['uprvkey']));
  81
  82                 return array_merge($data, ['signature' => $options]);
  83         }
  84
  85         private static function signableData($data)
  86         {
  87                 unset($data['signature']);
  88                 return $data;
  89         }
  90
  91         private static function signableOptions($options)
  92         {
  93                 $newopts = ['@context' => 'https://w3id.org/identity/v1'];
  94
  95                 unset($options['type']);
  96                 unset($options['id']);
  97                 unset($options['signatureValue']);
  98
  99                 return array_merge($newopts, $options);
 100         }
 101
 102         private static function hash($obj)
 103         {
 104                 return hash('sha256', JsonLD::normalize($obj));
 105         }
 106 }