src/Util/LDSignature.php

   1 <?php
   2
   3 namespace Friendica\Util;
   4
   5 use Friendica\Util\JsonLD;
   6 use Friendica\Util\DateTimeFormat;
   7 use Friendica\Protocol\ActivityPub;
   8
   9 /**
  10  * @brief Implements JSON-LD signatures
  11  *
  12  * Ported from Osada: https://framagit.org/macgirvin/osada
  13  */
  14 class LDSignature
  15 {
  16         public static function isSigned($data)
  17         {
  18                 return !empty($data['signature']);
  19         }
  20
  21         public static function getSigner($data)
  22         {
  23                 if (!self::isSigned($data)) {
  24                         return false;
  25                 }
  26
  27 /*
  28                 $creator = $data['signature']['creator'];
  29                 $actor = JsonLD::fetchElement($data, 'actor', 'id');
  30
  31                 $url = (strpos($creator, '#') ? substr($creator, 0, strpos($creator, '#')) : $creator);
  32
  33                 $profile = ActivityPub::fetchprofile($url);
  34                 if (!empty($profile)) {
  35                         logger('Taking key from creator ' . $creator, LOGGER_DEBUG);
  36                 } elseif ($url != $actor) {
  37                         $profile = ActivityPub::fetchprofile($actor);
  38                         if (empty($profile)) {
  39                                 return false;
  40                         }
  41                         logger('Taking key from actor ' . $actor, LOGGER_DEBUG);
  42                 }
  43
  44 */
  45                 $actor = JsonLD::fetchElement($data, 'actor', 'id');
  46                 if (empty($actor)) {
  47                         return false;
  48                 }
  49
  50                 $profile = ActivityPub::fetchprofile($actor);
  51                 if (empty($profile['pubkey'])) {
  52                         return false;
  53                 }
  54                 $pubkey = $profile['pubkey'];
  55
  56                 $ohash = self::hash(self::signable_options($data['signature']));
  57                 $dhash = self::hash(self::signable_data($data));
  58
  59                 $x = Crypto::rsaVerify($ohash . $dhash, base64_decode($data['signature']['signatureValue']), $pubkey);
  60                 logger('LD-verify: ' . intval($x));
  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' => random_string(64),
  74                         'creator' => $owner['url'] . '#main-key',
  75                         'created' => DateTimeFormat::utcNow(DateTimeFormat::ATOM)
  76                 ];
  77
  78                 $ohash = self::hash(self::signable_options($options));
  79                 $dhash = self::hash(self::signable_data($data));
  80                 $options['signatureValue'] = base64_encode(Crypto::rsaSign($ohash . $dhash, $owner['uprvkey']));
  81
  82                 return array_merge($data, ['signature' => $options]);
  83         }
  84
  85         private static function signable_data($data)
  86         {
  87                 unset($data['signature']);
  88                 return $data;
  89         }
  90
  91         private static function signable_options($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 }