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\ItemURI;
  31 use Friendica\Model\User;
  32 use Friendica\Network\HTTPClient\Client\HttpClientAccept;
  33 use Friendica\Network\HTTPClient\Client\HttpClientOptions;
  34
  35 /**
  36  * Implements HTTP Signatures per draft-cavage-http-signatures-07.
  37  *
  38  * Ported from Hubzilla: https://framagit.org/hubzilla/core/blob/master/Zotlabs/Web/HTTPSig.php
  39  *
  40  * Other parts of the code for HTTP signing are taken from the Osada project.
  41  * https://framagit.org/macgirvin/osada
  42  *
  43  * @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
  44  */
  45
  46 class HTTPSignature
  47 {
  48         // See draft-cavage-http-signatures-08
  49         /**
  50          * Verifies a magic request
  51          *
  52          * @param $key
  53          *
  54          * @return array with verification data
  55          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
  56          */
  57         public static function verifyMagic($key)
  58         {
  59                 $headers   = null;
  60                 $spoofable = false;
  61                 $result = [
  62                         'signer'         => '',
  63                         'header_signed'  => false,
  64                         'header_valid'   => false
  65                 ];
  66
  67                 // Decide if $data arrived via controller submission or curl.
  68                 $headers = [];
  69                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()).' '.$_SERVER['REQUEST_URI'];
  70
  71                 foreach ($_SERVER as $k => $v) {
  72                         if (strpos($k, 'HTTP_') === 0) {
  73                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
  74                                 $headers[$field] = $v;
  75                         }
  76                 }
  77
  78                 $sig_block = null;
  79
  80                 $sig_block = self::parseSigheader($headers['authorization']);
  81
  82                 if (!$sig_block) {
  83                         Logger::notice('no signature provided.');
  84                         return $result;
  85                 }
  86
  87                 $result['header_signed'] = true;
  88
  89                 $signed_headers = $sig_block['headers'];
  90                 if (!$signed_headers) {
  91                         $signed_headers = ['date'];
  92                 }
  93
  94                 $signed_data = '';
  95                 foreach ($signed_headers as $h) {
  96                         if (array_key_exists($h, $headers)) {
  97                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
  98                         }
  99                         if (strpos($h, '.')) {
 100                                 $spoofable = true;
 101                         }
 102                 }
 103
 104                 $signed_data = rtrim($signed_data, "\n");
 105
 106                 $algorithm = 'sha512';
 107
 108                 if ($key && function_exists($key)) {
 109                         $result['signer'] = $sig_block['keyId'];
 110                         $key = $key($sig_block['keyId']);
 111                 }
 112
 113                 Logger::info('Got keyID ' . $sig_block['keyId']);
 114
 115                 if (!$key) {
 116                         return $result;
 117                 }
 118
 119                 $x = Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm);
 120
 121                 Logger::info('verified: ' . $x);
 122
 123                 if (!$x) {
 124                         return $result;
 125                 }
 126
 127                 if (!$spoofable) {
 128                         $result['header_valid'] = true;
 129                 }
 130
 131                 return $result;
 132         }
 133
 134         /**
 135          * @param array   $head
 136          * @param string  $prvkey
 137          * @param string  $keyid (optional, default 'Key')
 138          *
 139          * @return array
 140          */
 141         public static function createSig($head, $prvkey, $keyid = 'Key')
 142         {
 143                 $return_headers = [];
 144                 if (!empty($head)) {
 145                         $return_headers = $head;
 146                 }
 147
 148                 $alg = 'sha512';
 149                 $algorithm = 'rsa-sha512';
 150
 151                 $x = self::sign($head, $prvkey, $alg);
 152
 153                 $headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
 154                         . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
 155
 156                 $return_headers['Authorization'] = ['Signature ' . $headerval];
 157
 158                 return $return_headers;
 159         }
 160
 161         /**
 162          * @param array  $head
 163          * @param string $prvkey
 164          * @param string $alg (optional) default 'sha256'
 165          *
 166          * @return array
 167          */
 168         private static function sign($head, $prvkey, $alg = 'sha256')
 169         {
 170                 $ret = [];
 171                 $headers = '';
 172                 $fields  = '';
 173
 174                 foreach ($head as $k => $v) {
 175                         if (is_array($v)) {
 176                                 $v = implode(', ', $v);
 177                         }
 178                         $headers .= strtolower($k) . ': ' . trim($v) . "\n";
 179                         if ($fields) {
 180                                 $fields .= ' ';
 181                         }
 182                         $fields .= strtolower($k);
 183                 }
 184                 // strip the trailing linefeed
 185                 $headers = rtrim($headers, "\n");
 186
 187                 $sig = base64_encode(Crypto::rsaSign($headers, $prvkey, $alg));
 188
 189                 $ret['headers']   = $fields;
 190                 $ret['signature'] = $sig;
 191
 192                 return $ret;
 193         }
 194
 195         /**
 196          * @param string $header
 197          * @return array associative array with
 198          *   - \e string \b keyID
 199          *   - \e string \b created
 200          *   - \e string \b expires
 201          *   - \e string \b algorithm
 202          *   - \e array  \b headers
 203          *   - \e string \b signature
 204          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 205          */
 206         public static function parseSigheader($header)
 207         {
 208                 // Remove obsolete folds
 209                 $header = preg_replace('/\n\s+/', ' ', $header);
 210
 211                 $token = "[!#$%&'*+.^_`|~0-9A-Za-z-]";
 212
 213                 $quotedString = '"(?:\\\\.|[^"\\\\])*"';
 214
 215                 $regex = "/($token+)=($quotedString|$token+)/ism";
 216
 217                 $matches = [];
 218                 preg_match_all($regex, $header, $matches, PREG_SET_ORDER);
 219
 220                 $headers = [];
 221                 foreach ($matches as $match) {
 222                         $headers[$match[1]] = trim($match[2] ?: $match[3], '"');
 223                 }
 224
 225                 // if the header is encrypted, decrypt with (default) site private key and continue
 226                 if (!empty($headers['iv'])) {
 227                         $header = self::decryptSigheader($headers, DI::config()->get('system', 'prvkey'));
 228                         return self::parseSigheader($header);
 229                 }
 230
 231                 $return = [
 232                         'keyId'     => $headers['keyId'] ?? '',
 233                         'algorithm' => $headers['algorithm'] ?? 'rsa-sha256',
 234                         'created'   => $headers['created'] ?? null,
 235                         'expires'   => $headers['expires'] ?? null,
 236                         'headers'   => explode(' ', $headers['headers'] ?? ''),
 237                         'signature' => base64_decode(preg_replace('/\s+/', '', $headers['signature'] ?? '')),
 238                 ];
 239
 240                 if (!empty($return['signature']) && !empty($return['algorithm']) && empty($return['headers'])) {
 241                         $return['headers'] = ['date'];
 242                 }
 243
 244                 return $return;
 245         }
 246
 247         /**
 248          * @param array  $headers Signature headers
 249          * @param string $prvkey  The site private key
 250          * @return string Decrypted signature string
 251          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 252          */
 253         private static function decryptSigheader(array $headers, string $prvkey)
 254         {
 255                 if (!empty($headers['iv']) && !empty($headers['key']) && !empty($headers['data'])) {
 256                         return Crypto::unencapsulate($headers, $prvkey);
 257                 }
 258
 259                 return '';
 260         }
 261
 262         /*
 263          * Functions for ActivityPub
 264          */
 265
 266         /**
 267          * Transmit given data to a target for a user
 268          *
 269          * @param array   $data   Data that is about to be send
 270          * @param string  $target The URL of the inbox
 271          * @param integer $uid    User id of the sender
 272          *
 273          * @return boolean Was the transmission successful?
 274          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 275          */
 276         public static function transmit($data, $target, $uid)
 277         {
 278                 $owner = User::getOwnerDataById($uid);
 279
 280                 if (!$owner) {
 281                         return;
 282                 }
 283
 284                 $content = json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
 285
 286                 // Header data that is about to be signed.
 287                 $host = parse_url($target, PHP_URL_HOST);
 288                 $path = parse_url($target, PHP_URL_PATH);
 289                 $digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
 290                 $content_length = strlen($content);
 291                 $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 292
 293                 $headers = [
 294                         'Date' => $date,
 295                         'Content-Length' => $content_length,
 296                         'Digest' => $digest,
 297                         'Host' => $host
 298                 ];
 299
 300                 $signed_data = "(request-target): post " . $path . "\ndate: ". $date . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
 301
 302                 $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 303
 304                 $headers['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date content-length digest host",signature="' . $signature . '"';
 305
 306                 $headers['Content-Type'] = 'application/activity+json';
 307
 308                 $postResult = DI::httpClient()->post($target, $content, $headers);
 309                 $return_code = $postResult->getReturnCode();
 310
 311                 Logger::info('Transmit to ' . $target . ' returned ' . $return_code);
 312
 313                 $success = ($return_code >= 200) && ($return_code <= 299);
 314
 315                 self::setInboxStatus($target, $success);
 316
 317                 return $success;
 318         }
 319
 320         /**
 321          * Set the delivery status for a given inbox
 322          *
 323          * @param string  $url     The URL of the inbox
 324          * @param boolean $success Transmission status
 325          * @param boolean $shared  The inbox is a shared inbox
 326          */
 327         static public function setInboxStatus($url, $success, $shared = false)
 328         {
 329                 $now = DateTimeFormat::utcNow();
 330
 331                 $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 332                 if (!DBA::isResult($status)) {
 333                         DBA::insert('inbox-status', ['url' => $url, 'uri-id' => ItemURI::getIdByURI($url), 'created' => $now, 'shared' => $shared], Database::INSERT_IGNORE);
 334                         $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 335                 }
 336
 337                 if ($success) {
 338                         $fields = ['success' => $now];
 339                 } else {
 340                         $fields = ['failure' => $now];
 341                 }
 342
 343                 if ($status['failure'] > DBA::NULL_DATETIME) {
 344                         $new_previous_stamp = strtotime($status['failure']);
 345                         $old_previous_stamp = strtotime($status['previous']);
 346
 347                         // Only set "previous" with at least one day difference.
 348                         // We use this to assure to not accidentally archive too soon.
 349                         if (($new_previous_stamp - $old_previous_stamp) >= 86400) {
 350                                 $fields['previous'] = $status['failure'];
 351                         }
 352                 }
 353
 354                 if (!$success) {
 355                         if ($status['success'] <= DBA::NULL_DATETIME) {
 356                                 $stamp1 = strtotime($status['created']);
 357                         } else {
 358                                 $stamp1 = strtotime($status['success']);
 359                         }
 360
 361                         $stamp2 = strtotime($now);
 362                         $previous_stamp = strtotime($status['previous']);
 363
 364                         // Archive the inbox when there had been failures for five days.
 365                         // Additionally ensure that at least one previous attempt has to be in between.
 366                         if ((($stamp2 - $stamp1) >= 86400 * 5) && ($previous_stamp > $stamp1)) {
 367                                 $fields['archive'] = true;
 368                         }
 369                 } else {
 370                         $fields['archive'] = false;
 371                 }
 372
 373                 if (empty($status['uri-id'])) {
 374                         $fields['uri-id'] = ItemURI::getIdByURI($url);
 375                 }
 376
 377                 DBA::update('inbox-status', $fields, ['url' => $url]);
 378         }
 379
 380         /**
 381          * Fetches JSON data for a user
 382          *
 383          * @param string  $request request url
 384          * @param integer $uid     User id of the requester
 385          *
 386          * @return array JSON array
 387          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 388          */
 389         public static function fetch($request, $uid)
 390         {
 391                 $curlResult = self::fetchRaw($request, $uid);
 392
 393                 if (empty($curlResult)) {
 394                         return false;
 395                 }
 396
 397                 if (!$curlResult->isSuccess() || empty($curlResult->getBody())) {
 398                         return false;
 399                 }
 400
 401                 $content = json_decode($curlResult->getBody(), true);
 402                 if (empty($content) || !is_array($content)) {
 403                         return false;
 404                 }
 405
 406                 return $content;
 407         }
 408
 409         /**
 410          * Fetches raw data for a user
 411          *
 412          * @param string  $request request url
 413          * @param integer $uid     User id of the requester
 414          * @param boolean $binary  TRUE if asked to return binary results (file download) (default is "false")
 415          * @param array   $opts    (optional parameters) assoziative array with:
 416          *                         'accept_content' => supply Accept: header with 'accept_content' as the value
 417          *                         'timeout' => int Timeout in seconds, default system config value or 60 seconds
 418          *                         'nobody' => only return the header
 419          *                         'cookiejar' => path to cookie jar file
 420          *
 421          * @return \Friendica\Network\HTTPClient\Capability\ICanHandleHttpResponses CurlResult
 422          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 423          */
 424         public static function fetchRaw($request, $uid = 0, $opts = [HttpClientOptions::ACCEPT_CONTENT => [HttpClientAccept::JSON_AS]])
 425         {
 426                 $header = [];
 427
 428                 if (!empty($uid)) {
 429                         $owner = User::getOwnerDataById($uid);
 430                         if (!$owner) {
 431                                 return;
 432                         }
 433                 } else {
 434                         $owner = User::getSystemAccount();
 435                         if (!$owner) {
 436                                 return;
 437                         }
 438                 }
 439
 440                 if (!empty($owner['uprvkey'])) {
 441                         // Header data that is about to be signed.
 442                         $host = parse_url($request, PHP_URL_HOST);
 443                         $path = parse_url($request, PHP_URL_PATH);
 444                         $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 445
 446                         $header['Date'] = $date;
 447                         $header['Host'] = $host;
 448
 449                         $signed_data = "(request-target): get " . $path . "\ndate: ". $date . "\nhost: " . $host;
 450
 451                         $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 452
 453                         $header['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date host",signature="' . $signature . '"';
 454                 }
 455
 456                 $curl_opts                             = $opts;
 457                 $curl_opts[HttpClientOptions::HEADERS] = $header;
 458
 459                 if (!empty($opts['nobody'])) {
 460                         $curlResult = DI::httpClient()->head($request, $curl_opts);
 461                 } else {
 462                         $curlResult = DI::httpClient()->get($request, HttpClientAccept::JSON_AS, $curl_opts);
 463                 }
 464                 $return_code = $curlResult->getReturnCode();
 465
 466                 Logger::info('Fetched for user ' . $uid . ' from ' . $request . ' returned ' . $return_code);
 467
 468                 return $curlResult;
 469         }
 470
 471         /**
 472          * Gets a signer from a given HTTP request
 473          *
 474          * @param $content
 475          * @param $http_headers
 476          *
 477          * @return string Signer
 478          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 479          */
 480         public static function getSigner($content, $http_headers)
 481         {
 482                 if (empty($http_headers['HTTP_SIGNATURE'])) {
 483                         Logger::debug('No HTTP_SIGNATURE header');
 484                         return false;
 485                 }
 486
 487                 if (!empty($content)) {
 488                         $object = json_decode($content, true);
 489                         if (empty($object)) {
 490                                 Logger::info('No object');
 491                                 return false;
 492                         }
 493
 494                         $actor = JsonLD::fetchElement($object, 'actor', 'id');
 495                 } else {
 496                         $actor = '';
 497                 }
 498
 499                 $headers = [];
 500                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()) . ' ' . parse_url($http_headers['REQUEST_URI'], PHP_URL_PATH);
 501
 502                 // First take every header
 503                 foreach ($http_headers as $k => $v) {
 504                         $field = str_replace('_', '-', strtolower($k));
 505                         $headers[$field] = $v;
 506                 }
 507
 508                 // Now add every http header
 509                 foreach ($http_headers as $k => $v) {
 510                         if (strpos($k, 'HTTP_') === 0) {
 511                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
 512                                 $headers[$field] = $v;
 513                         }
 514                 }
 515
 516                 $sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 517
 518                 // Add fields from the signature block to the header. See issue 8845
 519                 if (!empty($sig_block['created']) && empty($headers['(created)'])) {
 520                         $headers['(created)'] = $sig_block['created'];
 521                 }
 522
 523                 if (!empty($sig_block['expires']) && empty($headers['(expires)'])) {
 524                         $headers['(expires)'] = $sig_block['expires'];
 525                 }
 526
 527                 if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
 528                         Logger::info('No headers or keyId');
 529                         return false;
 530                 }
 531
 532                 $signed_data = '';
 533                 foreach ($sig_block['headers'] as $h) {
 534                         if (array_key_exists($h, $headers)) {
 535                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 536                         } else {
 537                                 Logger::info('Requested header field not found', ['field' => $h, 'header' => $headers]);
 538                         }
 539                 }
 540                 $signed_data = rtrim($signed_data, "\n");
 541
 542                 if (empty($signed_data)) {
 543                         Logger::info('Signed data is empty');
 544                         return false;
 545                 }
 546
 547                 $algorithm = null;
 548
 549                 // Wildcard value where signing algorithm should be derived from keyId
 550                 // @see https://tools.ietf.org/html/draft-ietf-httpbis-message-signatures-00#section-4.1
 551                 // Defaulting to SHA256 as it seems to be the prevalent implementation
 552                 // @see https://arewehs2019yet.vpzom.click
 553                 if ($sig_block['algorithm'] === 'hs2019') {
 554                         $algorithm = 'sha256';
 555                 }
 556
 557                 if ($sig_block['algorithm'] === 'rsa-sha256') {
 558                         $algorithm = 'sha256';
 559                 }
 560
 561                 if ($sig_block['algorithm'] === 'rsa-sha512') {
 562                         $algorithm = 'sha512';
 563                 }
 564
 565                 if (empty($algorithm)) {
 566                         Logger::info('No alagorithm');
 567                         return false;
 568                 }
 569
 570                 $key = self::fetchKey($sig_block['keyId'], $actor);
 571                 if (empty($key)) {
 572                         Logger::info('Empty key');
 573                         return false;
 574                 }
 575
 576                 if (!empty($key['url']) && !empty($key['type']) && ($key['type'] == 'Tombstone')) {
 577                         Logger::info('Actor is a tombstone', ['key' => $key]);
 578
 579                         if (!Contact::isLocal($key['url'])) {
 580                                 // We now delete everything that we possibly knew from this actor
 581                                 Contact::deleteContactByUrl($key['url']);
 582                         }
 583                         return null;
 584                 }
 585
 586                 if (empty($key['pubkey'])) {
 587                         Logger::info('Empty pubkey');
 588                         return false;
 589                 }
 590
 591                 if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key['pubkey'], $algorithm)) {
 592                         Logger::info('Verification failed', ['signed_data' => $signed_data, 'algorithm' => $algorithm, 'header' => $sig_block['headers'], 'http_headers' => $http_headers]);
 593                         return false;
 594                 }
 595
 596                 $hasGoodSignedContent = false;
 597
 598                 // Check the digest when it is part of the signed data
 599                 if (!empty($content) && in_array('digest', $sig_block['headers'])) {
 600                         $digest = explode('=', $headers['digest'], 2);
 601                         if ($digest[0] === 'SHA-256') {
 602                                 $hashalg = 'sha256';
 603                         }
 604                         if ($digest[0] === 'SHA-512') {
 605                                 $hashalg = 'sha512';
 606                         }
 607
 608                         /// @todo add all hashes from the rfc
 609
 610                         if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
 611                                 Logger::info('Digest does not match');
 612                                 return false;
 613                         }
 614
 615                         $hasGoodSignedContent = true;
 616                 }
 617
 618                 if (in_array('date', $sig_block['headers']) && !empty($headers['date'])) {
 619                         $created = strtotime($headers['date']);
 620                 } elseif (in_array('(created)', $sig_block['headers']) && !empty($sig_block['created'])) {
 621                         $created = $sig_block['created'];
 622                 } else {
 623                         $created = 0;
 624                 }
 625
 626                 if (in_array('(expires)', $sig_block['headers']) && !empty($sig_block['expires'])) {
 627                         $expired = min($sig_block['expires'], $created + 300);
 628                 } else {
 629                         $expired = $created + 300;
 630                 }
 631
 632                 //  Check if the signed date field is in an acceptable range
 633                 if (!empty($created)) {
 634                         $current = time();
 635
 636                         // Calculate with a grace period of 60 seconds to avoid slight time differences between the servers
 637                         if (($created - 60) > $current) {
 638                                 Logger::notice('Signature created in the future', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 639                                 return false;
 640                         }
 641
 642                         if ($current > $expired) {
 643                                 Logger::notice('Signature expired', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 644                                 return false;
 645                         }
 646
 647                         Logger::debug('Valid creation date', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 648                         $hasGoodSignedContent = true;
 649                 }
 650
 651                 // Check the content-length when it is part of the signed data
 652                 if (in_array('content-length', $sig_block['headers'])) {
 653                         if (strlen($content) != $headers['content-length']) {
 654                                 Logger::info('Content length does not match');
 655                                 return false;
 656                         }
 657                 }
 658
 659                 // Ensure that the authentication had been done with some content
 660                 // Without this check someone could authenticate with fakeable data
 661                 if (!$hasGoodSignedContent) {
 662                         Logger::info('No good signed content');
 663                         return false;
 664                 }
 665
 666                 return $key['url'];
 667         }
 668
 669         /**
 670          * fetches a key for a given id and actor
 671          *
 672          * @param $id
 673          * @param $actor
 674          *
 675          * @return array with actor url and public key
 676          * @throws \Exception
 677          */
 678         private static function fetchKey($id, $actor)
 679         {
 680                 $url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
 681
 682                 $profile = APContact::getByURL($url);
 683                 if (!empty($profile)) {
 684                         Logger::info('Taking key from id', ['id' => $id]);
 685                         return ['url' => $url, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 686                 } elseif ($url != $actor) {
 687                         $profile = APContact::getByURL($actor);
 688                         if (!empty($profile)) {
 689                                 Logger::info('Taking key from actor', ['actor' => $actor]);
 690                                 return ['url' => $actor, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 691                         }
 692                 }
 693
 694                 Logger::notice('Key could not be fetched', ['url' => $url, 'actor' => $actor]);
 695                 return false;
 696         }
 697 }