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 class LDSignature
  10 {
  11         public static function isSigned($data)
  12         {
  13                 return !empty($data['signature']);
  14         }
  15
  16         public static function getSigner($data)
  17         {
  18                 if (!self::isSigned($data)) {
  19                         return false;
  20                 }
  21
  22 /*
  23                 $creator = $data['signature']['creator'];
  24                 $actor = JsonLD::fetchElement($data, 'actor', 'id');
  25
  26                 $url = (strpos($creator, '#') ? substr($creator, 0, strpos($creator, '#')) : $creator);
  27
  28                 $profile = ActivityPub::fetchprofile($url);
  29                 if (!empty($profile)) {
  30                         logger('Taking key from creator ' . $creator, LOGGER_DEBUG);
  31                 } elseif ($url != $actor) {
  32                         $profile = ActivityPub::fetchprofile($actor);
  33                         if (empty($profile)) {
  34                                 return false;
  35                         }
  36                         logger('Taking key from actor ' . $actor, LOGGER_DEBUG);
  37                 }
  38
  39 */
  40                 $actor = JsonLD::fetchElement($data, 'actor', 'id');
  41                 if (empty($actor)) {
  42                         return false;
  43                 }
  44
  45                 $profile = ActivityPub::fetchprofile($actor);
  46                 if (empty($profile['pubkey'])) {
  47                         return false;
  48                 }
  49                 $pubkey = $profile['pubkey'];
  50
  51                 $ohash = self::hash(self::signable_options($data['signature']));
  52                 $dhash = self::hash(self::signable_data($data));
  53
  54                 $x = Crypto::rsaVerify($ohash . $dhash, base64_decode($data['signature']['signatureValue']), $pubkey);
  55                 logger('LD-verify: ' . intval($x));
  56
  57                 if (empty($x)) {
  58                         return false;
  59                 } else {
  60                         return $actor;
  61                 }
  62         }
  63
  64         public static function sign($data, $owner)
  65         {
  66                 $options = [
  67                         'type' => 'RsaSignature2017',
  68                         'nonce' => random_string(64),
  69                         'creator' => $owner['url'] . '#main-key',
  70                         'created' => DateTimeFormat::utcNow(DateTimeFormat::ATOM)
  71                 ];
  72
  73                 $ohash = self::hash(self::signable_options($options));
  74                 $dhash = self::hash(self::signable_data($data));
  75                 $options['signatureValue'] = base64_encode(Crypto::rsaSign($ohash . $dhash, $owner['uprvkey']));
  76
  77                 return array_merge($data, ['signature' => $options]);
  78         }
  79
  80
  81         private static function signable_data($data)
  82         {
  83                 unset($data['signature']);
  84                 return $data;
  85         }
  86
  87
  88         private static function signable_options($options)
  89         {
  90                 $newopts = ['@context' => 'https://w3id.org/identity/v1'];
  91                 if (!empty($options)) {
  92                         foreach ($options as $k => $v) {
  93                                 if (!in_array($k, ['type', 'id', 'signatureValue'])) {
  94                                         $newopts[$k] = $v;
  95                                 }
  96                         }
  97                 }
  98                 return $newopts;
  99         }
 100
 101         private static function hash($obj)
 102         {
 103                 return hash('sha256', JsonLD::normalize($obj));
 104         }
 105 }