src/Util/HTTPSignature.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\Database\Database;
  26 use Friendica\Database\DBA;
  27 use Friendica\DI;
  28 use Friendica\Model\APContact;
  29 use Friendica\Model\Contact;
  30 use Friendica\Model\User;
  31 use Friendica\Network\HTTPClient\Client\HttpClient;
  32 use Friendica\Network\HTTPClient\Client\HttpClientOptions;
  33
  34 /**
  35  * Implements HTTP Signatures per draft-cavage-http-signatures-07.
  36  *
  37  * Ported from Hubzilla: https://framagit.org/hubzilla/core/blob/master/Zotlabs/Web/HTTPSig.php
  38  *
  39  * Other parts of the code for HTTP signing are taken from the Osada project.
  40  * https://framagit.org/macgirvin/osada
  41  *
  42  * @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
  43  */
  44
  45 class HTTPSignature
  46 {
  47         // See draft-cavage-http-signatures-08
  48         /**
  49          * Verifies a magic request
  50          *
  51          * @param $key
  52          *
  53          * @return array with verification data
  54          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
  55          */
  56         public static function verifyMagic($key)
  57         {
  58                 $headers   = null;
  59                 $spoofable = false;
  60                 $result = [
  61                         'signer'         => '',
  62                         'header_signed'  => false,
  63                         'header_valid'   => false
  64                 ];
  65
  66                 // Decide if $data arrived via controller submission or curl.
  67                 $headers = [];
  68                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()).' '.$_SERVER['REQUEST_URI'];
  69
  70                 foreach ($_SERVER as $k => $v) {
  71                         if (strpos($k, 'HTTP_') === 0) {
  72                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
  73                                 $headers[$field] = $v;
  74                         }
  75                 }
  76
  77                 $sig_block = null;
  78
  79                 $sig_block = self::parseSigheader($headers['authorization']);
  80
  81                 if (!$sig_block) {
  82                         Logger::notice('no signature provided.');
  83                         return $result;
  84                 }
  85
  86                 $result['header_signed'] = true;
  87
  88                 $signed_headers = $sig_block['headers'];
  89                 if (!$signed_headers) {
  90                         $signed_headers = ['date'];
  91                 }
  92
  93                 $signed_data = '';
  94                 foreach ($signed_headers as $h) {
  95                         if (array_key_exists($h, $headers)) {
  96                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
  97                         }
  98                         if (strpos($h, '.')) {
  99                                 $spoofable = true;
 100                         }
 101                 }
 102
 103                 $signed_data = rtrim($signed_data, "\n");
 104
 105                 $algorithm = 'sha512';
 106
 107                 if ($key && function_exists($key)) {
 108                         $result['signer'] = $sig_block['keyId'];
 109                         $key = $key($sig_block['keyId']);
 110                 }
 111
 112                 Logger::info('Got keyID ' . $sig_block['keyId']);
 113
 114                 if (!$key) {
 115                         return $result;
 116                 }
 117
 118                 $x = Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm);
 119
 120                 Logger::info('verified: ' . $x);
 121
 122                 if (!$x) {
 123                         return $result;
 124                 }
 125
 126                 if (!$spoofable) {
 127                         $result['header_valid'] = true;
 128                 }
 129
 130                 return $result;
 131         }
 132
 133         /**
 134          * @param array   $head
 135          * @param string  $prvkey
 136          * @param string  $keyid (optional, default 'Key')
 137          *
 138          * @return array
 139          */
 140         public static function createSig($head, $prvkey, $keyid = 'Key')
 141         {
 142                 $return_headers = [];
 143                 if (!empty($head)) {
 144                         $return_headers = $head;
 145                 }
 146
 147                 $alg = 'sha512';
 148                 $algorithm = 'rsa-sha512';
 149
 150                 $x = self::sign($head, $prvkey, $alg);
 151
 152                 $headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
 153                         . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
 154
 155                 $return_headers['Authorization'] = ['Signature ' . $headerval];
 156
 157                 return $return_headers;
 158         }
 159
 160         /**
 161          * @param array  $head
 162          * @param string $prvkey
 163          * @param string $alg (optional) default 'sha256'
 164          *
 165          * @return array
 166          */
 167         private static function sign($head, $prvkey, $alg = 'sha256')
 168         {
 169                 $ret = [];
 170                 $headers = '';
 171                 $fields  = '';
 172
 173                 foreach ($head as $k => $v) {
 174                         if (is_array($v)) {
 175                                 $v = implode(', ', $v);
 176                         }
 177                         $headers .= strtolower($k) . ': ' . trim($v) . "\n";
 178                         if ($fields) {
 179                                 $fields .= ' ';
 180                         }
 181                         $fields .= strtolower($k);
 182                 }
 183                 // strip the trailing linefeed
 184                 $headers = rtrim($headers, "\n");
 185
 186                 $sig = base64_encode(Crypto::rsaSign($headers, $prvkey, $alg));
 187
 188                 $ret['headers']   = $fields;
 189                 $ret['signature'] = $sig;
 190
 191                 return $ret;
 192         }
 193
 194         /**
 195          * @param string $header
 196          * @return array associative array with
 197          *   - \e string \b keyID
 198          *   - \e string \b created
 199          *   - \e string \b expires
 200          *   - \e string \b algorithm
 201          *   - \e array  \b headers
 202          *   - \e string \b signature
 203          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 204          */
 205         public static function parseSigheader($header)
 206         {
 207                 // Remove obsolete folds
 208                 $header = preg_replace('/\n\s+/', ' ', $header);
 209
 210                 $token = "[!#$%&'*+.^_`|~0-9A-Za-z-]";
 211
 212                 $quotedString = '"(?:\\\\.|[^"\\\\])*"';
 213
 214                 $regex = "/($token+)=($quotedString|$token+)/ism";
 215
 216                 $matches = [];
 217                 preg_match_all($regex, $header, $matches, PREG_SET_ORDER);
 218
 219                 $headers = [];
 220                 foreach ($matches as $match) {
 221                         $headers[$match[1]] = trim($match[2] ?: $match[3], '"');
 222                 }
 223
 224                 // if the header is encrypted, decrypt with (default) site private key and continue
 225                 if (!empty($headers['iv'])) {
 226                         $header = self::decryptSigheader($headers, DI::config()->get('system', 'prvkey'));
 227                         return self::parseSigheader($header);
 228                 }
 229
 230                 $return = [
 231                         'keyId'     => $headers['keyId'] ?? '',
 232                         'algorithm' => $headers['algorithm'] ?? 'rsa-sha256',
 233                         'created'   => $headers['created'] ?? null,
 234                         'expires'   => $headers['expires'] ?? null,
 235                         'headers'   => explode(' ', $headers['headers'] ?? ''),
 236                         'signature' => base64_decode(preg_replace('/\s+/', '', $headers['signature'] ?? '')),
 237                 ];
 238
 239                 if (!empty($return['signature']) && !empty($return['algorithm']) && empty($return['headers'])) {
 240                         $return['headers'] = ['date'];
 241                 }
 242
 243                 return $return;
 244         }
 245
 246         /**
 247          * @param array  $headers Signature headers
 248          * @param string $prvkey  The site private key
 249          * @return string Decrypted signature string
 250          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 251          */
 252         private static function decryptSigheader(array $headers, string $prvkey)
 253         {
 254                 if (!empty($headers['iv']) && !empty($headers['key']) && !empty($headers['data'])) {
 255                         return Crypto::unencapsulate($headers, $prvkey);
 256                 }
 257
 258                 return '';
 259         }
 260
 261         /*
 262          * Functions for ActivityPub
 263          */
 264
 265         /**
 266          * Transmit given data to a target for a user
 267          *
 268          * @param array   $data   Data that is about to be send
 269          * @param string  $target The URL of the inbox
 270          * @param integer $uid    User id of the sender
 271          *
 272          * @return boolean Was the transmission successful?
 273          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 274          */
 275         public static function transmit($data, $target, $uid)
 276         {
 277                 $owner = User::getOwnerDataById($uid);
 278
 279                 if (!$owner) {
 280                         return;
 281                 }
 282
 283                 $content = json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
 284
 285                 // Header data that is about to be signed.
 286                 $host = parse_url($target, PHP_URL_HOST);
 287                 $path = parse_url($target, PHP_URL_PATH);
 288                 $digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
 289                 $content_length = strlen($content);
 290                 $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 291
 292                 $headers = [
 293                         'Date' => $date,
 294                         'Content-Length' => $content_length,
 295                         'Digest' => $digest,
 296                         'Host' => $host
 297                 ];
 298
 299                 $signed_data = "(request-target): post " . $path . "\ndate: ". $date . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
 300
 301                 $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 302
 303                 $headers['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date content-length digest host",signature="' . $signature . '"';
 304
 305                 $headers['Content-Type'] = 'application/activity+json';
 306
 307                 $postResult = DI::httpClient()->post($target, $content, $headers);
 308                 $return_code = $postResult->getReturnCode();
 309
 310                 Logger::info('Transmit to ' . $target . ' returned ' . $return_code);
 311
 312                 $success = ($return_code >= 200) && ($return_code <= 299);
 313
 314                 self::setInboxStatus($target, $success);
 315
 316                 return $success;
 317         }
 318
 319         /**
 320          * Set the delivery status for a given inbox
 321          *
 322          * @param string  $url     The URL of the inbox
 323          * @param boolean $success Transmission status
 324          * @param boolean $shared  The inbox is a shared inbox
 325          */
 326         static public function setInboxStatus($url, $success, $shared = false)
 327         {
 328                 $now = DateTimeFormat::utcNow();
 329
 330                 $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 331                 if (!DBA::isResult($status)) {
 332                         DBA::insert('inbox-status', ['url' => $url, 'created' => $now, 'shared' => $shared], Database::INSERT_IGNORE);
 333                         $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 334                 }
 335
 336                 if ($success) {
 337                         $fields = ['success' => $now];
 338                 } else {
 339                         $fields = ['failure' => $now];
 340                 }
 341
 342                 if ($status['failure'] > DBA::NULL_DATETIME) {
 343                         $new_previous_stamp = strtotime($status['failure']);
 344                         $old_previous_stamp = strtotime($status['previous']);
 345
 346                         // Only set "previous" with at least one day difference.
 347                         // We use this to assure to not accidentally archive too soon.
 348                         if (($new_previous_stamp - $old_previous_stamp) >= 86400) {
 349                                 $fields['previous'] = $status['failure'];
 350                         }
 351                 }
 352
 353                 if (!$success) {
 354                         if ($status['success'] <= DBA::NULL_DATETIME) {
 355                                 $stamp1 = strtotime($status['created']);
 356                         } else {
 357                                 $stamp1 = strtotime($status['success']);
 358                         }
 359
 360                         $stamp2 = strtotime($now);
 361                         $previous_stamp = strtotime($status['previous']);
 362
 363                         // Archive the inbox when there had been failures for five days.
 364                         // Additionally ensure that at least one previous attempt has to be in between.
 365                         if ((($stamp2 - $stamp1) >= 86400 * 5) && ($previous_stamp > $stamp1)) {
 366                                 $fields['archive'] = true;
 367                         }
 368                 } else {
 369                         $fields['archive'] = false;
 370                 }
 371
 372                 DBA::update('inbox-status', $fields, ['url' => $url]);
 373         }
 374
 375         /**
 376          * Fetches JSON data for a user
 377          *
 378          * @param string  $request request url
 379          * @param integer $uid     User id of the requester
 380          *
 381          * @return array JSON array
 382          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 383          */
 384         public static function fetch($request, $uid)
 385         {
 386                 $curlResult = self::fetchRaw($request, $uid);
 387
 388                 if (empty($curlResult)) {
 389                         return false;
 390                 }
 391
 392                 if (!$curlResult->isSuccess() || empty($curlResult->getBody())) {
 393                         return false;
 394                 }
 395
 396                 $content = json_decode($curlResult->getBody(), true);
 397                 if (empty($content) || !is_array($content)) {
 398                         return false;
 399                 }
 400
 401                 return $content;
 402         }
 403
 404         /**
 405          * Fetches raw data for a user
 406          *
 407          * @param string  $request request url
 408          * @param integer $uid     User id of the requester
 409          * @param boolean $binary  TRUE if asked to return binary results (file download) (default is "false")
 410          * @param array   $opts    (optional parameters) assoziative array with:
 411          *                         'accept_content' => supply Accept: header with 'accept_content' as the value
 412          *                         'timeout' => int Timeout in seconds, default system config value or 60 seconds
 413          *                         'nobody' => only return the header
 414          *                         'cookiejar' => path to cookie jar file
 415          *
 416          * @return \Friendica\Network\HTTPClient\Capability\ICanHandleHttpResponses CurlResult
 417          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 418          */
 419         public static function fetchRaw($request, $uid = 0, $opts = [HttpClientOptions::ACCEPT_CONTENT => [HttpClient::ACCEPT_JSON_AS]])
 420         {
 421                 $header = [];
 422
 423                 if (!empty($uid)) {
 424                         $owner = User::getOwnerDataById($uid);
 425                         if (!$owner) {
 426                                 return;
 427                         }
 428                 } else {
 429                         $owner = User::getSystemAccount();
 430                         if (!$owner) {
 431                                 return;
 432                         }
 433                 }
 434
 435                 if (!empty($owner['uprvkey'])) {
 436                         // Header data that is about to be signed.
 437                         $host = parse_url($request, PHP_URL_HOST);
 438                         $path = parse_url($request, PHP_URL_PATH);
 439                         $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 440
 441                         $header['Date'] = $date;
 442                         $header['Host'] = $host;
 443
 444                         $signed_data = "(request-target): get " . $path . "\ndate: ". $date . "\nhost: " . $host;
 445
 446                         $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 447
 448                         $header['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date host",signature="' . $signature . '"';
 449                 }
 450
 451                 $curl_opts                             = $opts;
 452                 $curl_opts[HttpClientOptions::HEADERS] = $header;
 453
 454                 if (!empty($opts['nobody'])) {
 455                         $curlResult = DI::httpClient()->head($request, $curl_opts);
 456                 } else {
 457                         $curlResult = DI::httpClient()->get($request, $curl_opts);
 458                 }
 459                 $return_code = $curlResult->getReturnCode();
 460
 461                 Logger::info('Fetched for user ' . $uid . ' from ' . $request . ' returned ' . $return_code);
 462
 463                 return $curlResult;
 464         }
 465
 466         /**
 467          * Gets a signer from a given HTTP request
 468          *
 469          * @param $content
 470          * @param $http_headers
 471          *
 472          * @return string Signer
 473          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 474          */
 475         public static function getSigner($content, $http_headers)
 476         {
 477                 if (empty($http_headers['HTTP_SIGNATURE'])) {
 478                         Logger::debug('No HTTP_SIGNATURE header');
 479                         return false;
 480                 }
 481
 482                 if (!empty($content)) {
 483                         $object = json_decode($content, true);
 484                         if (empty($object)) {
 485                                 Logger::info('No object');
 486                                 return false;
 487                         }
 488
 489                         $actor = JsonLD::fetchElement($object, 'actor', 'id');
 490                 } else {
 491                         $actor = '';
 492                 }
 493
 494                 $headers = [];
 495                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()) . ' ' . parse_url($http_headers['REQUEST_URI'], PHP_URL_PATH);
 496
 497                 // First take every header
 498                 foreach ($http_headers as $k => $v) {
 499                         $field = str_replace('_', '-', strtolower($k));
 500                         $headers[$field] = $v;
 501                 }
 502
 503                 // Now add every http header
 504                 foreach ($http_headers as $k => $v) {
 505                         if (strpos($k, 'HTTP_') === 0) {
 506                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
 507                                 $headers[$field] = $v;
 508                         }
 509                 }
 510
 511                 $sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 512
 513                 // Add fields from the signature block to the header. See issue 8845
 514                 if (!empty($sig_block['created']) && empty($headers['(created)'])) {
 515                         $headers['(created)'] = $sig_block['created'];
 516                 }
 517
 518                 if (!empty($sig_block['expires']) && empty($headers['(expires)'])) {
 519                         $headers['(expires)'] = $sig_block['expires'];
 520                 }
 521
 522                 if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
 523                         Logger::info('No headers or keyId');
 524                         return false;
 525                 }
 526
 527                 $signed_data = '';
 528                 foreach ($sig_block['headers'] as $h) {
 529                         if (array_key_exists($h, $headers)) {
 530                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 531                         } else {
 532                                 Logger::info('Requested header field not found', ['field' => $h, 'header' => $headers]);
 533                         }
 534                 }
 535                 $signed_data = rtrim($signed_data, "\n");
 536
 537                 if (empty($signed_data)) {
 538                         Logger::info('Signed data is empty');
 539                         return false;
 540                 }
 541
 542                 $algorithm = null;
 543
 544                 // Wildcard value where signing algorithm should be derived from keyId
 545                 // @see https://tools.ietf.org/html/draft-ietf-httpbis-message-signatures-00#section-4.1
 546                 // Defaulting to SHA256 as it seems to be the prevalent implementation
 547                 // @see https://arewehs2019yet.vpzom.click
 548                 if ($sig_block['algorithm'] === 'hs2019') {
 549                         $algorithm = 'sha256';
 550                 }
 551
 552                 if ($sig_block['algorithm'] === 'rsa-sha256') {
 553                         $algorithm = 'sha256';
 554                 }
 555
 556                 if ($sig_block['algorithm'] === 'rsa-sha512') {
 557                         $algorithm = 'sha512';
 558                 }
 559
 560                 if (empty($algorithm)) {
 561                         Logger::info('No alagorithm');
 562                         return false;
 563                 }
 564
 565                 $key = self::fetchKey($sig_block['keyId'], $actor);
 566                 if (empty($key)) {
 567                         Logger::info('Empty key');
 568                         return false;
 569                 }
 570
 571                 if (!empty($key['url']) && !empty($key['type']) && ($key['type'] == 'Tombstone')) {
 572                         Logger::info('Actor is a tombstone', ['key' => $key]);
 573
 574                         if (!Contact::isLocal($key['url'])) {
 575                                 // We now delete everything that we possibly knew from this actor
 576                                 Contact::deleteContactByUrl($key['url']);
 577                         }
 578                         return null;
 579                 }
 580
 581                 if (empty($key['pubkey'])) {
 582                         Logger::info('Empty pubkey');
 583                         return false;
 584                 }
 585
 586                 if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key['pubkey'], $algorithm)) {
 587                         Logger::info('Verification failed', ['signed_data' => $signed_data, 'algorithm' => $algorithm, 'header' => $sig_block['headers'], 'http_headers' => $http_headers]);
 588                         return false;
 589                 }
 590
 591                 $hasGoodSignedContent = false;
 592
 593                 // Check the digest when it is part of the signed data
 594                 if (!empty($content) && in_array('digest', $sig_block['headers'])) {
 595                         $digest = explode('=', $headers['digest'], 2);
 596                         if ($digest[0] === 'SHA-256') {
 597                                 $hashalg = 'sha256';
 598                         }
 599                         if ($digest[0] === 'SHA-512') {
 600                                 $hashalg = 'sha512';
 601                         }
 602
 603                         /// @todo add all hashes from the rfc
 604
 605                         if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
 606                                 Logger::info('Digest does not match');
 607                                 return false;
 608                         }
 609
 610                         $hasGoodSignedContent = true;
 611                 }
 612
 613                 if (in_array('date', $sig_block['headers']) && !empty($headers['date'])) {
 614                         $created = strtotime($headers['date']);
 615                 } elseif (in_array('(created)', $sig_block['headers']) && !empty($sig_block['created'])) {
 616                         $created = $sig_block['created'];
 617                 } else {
 618                         $created = 0;
 619                 }
 620
 621                 if (in_array('(expires)', $sig_block['headers']) && !empty($sig_block['expires'])) {
 622                         $expired = min($sig_block['expires'], $created + 300);
 623                 } else {
 624                         $expired = $created + 300;
 625                 }
 626
 627                 //  Check if the signed date field is in an acceptable range
 628                 if (!empty($created)) {
 629                         $current = time();
 630
 631                         // Calculate with a grace period of 60 seconds to avoid slight time differences between the servers
 632                         if (($created - 60) > $current) {
 633                                 Logger::notice('Signature created in the future', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 634                                 return false;
 635                         }
 636
 637                         if ($current > $expired) {
 638                                 Logger::notice('Signature expired', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 639                                 return false;
 640                         }
 641
 642                         Logger::debug('Valid creation date', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 643                         $hasGoodSignedContent = true;
 644                 }
 645
 646                 // Check the content-length when it is part of the signed data
 647                 if (in_array('content-length', $sig_block['headers'])) {
 648                         if (strlen($content) != $headers['content-length']) {
 649                                 Logger::info('Content length does not match');
 650                                 return false;
 651                         }
 652                 }
 653
 654                 // Ensure that the authentication had been done with some content
 655                 // Without this check someone could authenticate with fakeable data
 656                 if (!$hasGoodSignedContent) {
 657                         Logger::info('No good signed content');
 658                         return false;
 659                 }
 660
 661                 return $key['url'];
 662         }
 663
 664         /**
 665          * fetches a key for a given id and actor
 666          *
 667          * @param $id
 668          * @param $actor
 669          *
 670          * @return array with actor url and public key
 671          * @throws \Exception
 672          */
 673         private static function fetchKey($id, $actor)
 674         {
 675                 $url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
 676
 677                 $profile = APContact::getByURL($url);
 678                 if (!empty($profile)) {
 679                         Logger::info('Taking key from id', ['id' => $id]);
 680                         return ['url' => $url, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 681                 } elseif ($url != $actor) {
 682                         $profile = APContact::getByURL($actor);
 683                         if (!empty($profile)) {
 684                                 Logger::info('Taking key from actor', ['actor' => $actor]);
 685                                 return ['url' => $actor, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 686                         }
 687                 }
 688
 689                 Logger::notice('Key could not be fetched', ['url' => $url, 'actor' => $actor]);
 690                 return false;
 691         }
 692 }