src/Util/HTTPSignature.php

   1 <?php
   2 /**
   3  * @copyright Copyright (C) 2010-2023, 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\Capability\ICanHandleHttpResponses;
  33 use Friendica\Network\HTTPClient\Client\HttpClientAccept;
  34 use Friendica\Network\HTTPClient\Client\HttpClientOptions;
  35
  36 /**
  37  * Implements HTTP Signatures per draft-cavage-http-signatures-07.
  38  *
  39  * Ported from Hubzilla: https://framagit.org/hubzilla/core/blob/master/Zotlabs/Web/HTTPSig.php
  40  *
  41  * Other parts of the code for HTTP signing are taken from the Osada project.
  42  * https://framagit.org/macgirvin/osada
  43  *
  44  * @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
  45  */
  46
  47 class HTTPSignature
  48 {
  49         // See draft-cavage-http-signatures-08
  50         /**
  51          * Verifies a magic request
  52          *
  53          * @param $key
  54          *
  55          * @return array with verification data
  56          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
  57          */
  58         public static function verifyMagic(string $key): array
  59         {
  60                 $headers   = null;
  61                 $spoofable = false;
  62                 $result = [
  63                         'signer'         => '',
  64                         'header_signed'  => false,
  65                         'header_valid'   => false
  66                 ];
  67
  68                 // Decide if $data arrived via controller submission or curl.
  69                 $headers = [];
  70                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()).' '.$_SERVER['REQUEST_URI'];
  71
  72                 foreach ($_SERVER as $k => $v) {
  73                         if (strpos($k, 'HTTP_') === 0) {
  74                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
  75                                 $headers[$field] = $v;
  76                         }
  77                 }
  78
  79                 $sig_block = null;
  80
  81                 $sig_block = self::parseSigheader($headers['authorization']);
  82
  83                 if (!$sig_block) {
  84                         Logger::notice('no signature provided.');
  85                         return $result;
  86                 }
  87
  88                 $result['header_signed'] = true;
  89
  90                 $signed_headers = $sig_block['headers'];
  91                 if (!$signed_headers) {
  92                         $signed_headers = ['date'];
  93                 }
  94
  95                 $signed_data = '';
  96                 foreach ($signed_headers as $h) {
  97                         if (array_key_exists($h, $headers)) {
  98                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
  99                         }
 100                         if (strpos($h, '.')) {
 101                                 $spoofable = true;
 102                         }
 103                 }
 104
 105                 $signed_data = rtrim($signed_data, "\n");
 106
 107                 $algorithm = 'sha512';
 108
 109                 if ($key && function_exists($key)) {
 110                         $result['signer'] = $sig_block['keyId'];
 111                         $key = $key($sig_block['keyId']);
 112                 }
 113
 114                 Logger::info('Got keyID ' . $sig_block['keyId']);
 115
 116                 if (!$key) {
 117                         return $result;
 118                 }
 119
 120                 $x = Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm);
 121
 122                 Logger::info('verified: ' . $x);
 123
 124                 if (!$x) {
 125                         return $result;
 126                 }
 127
 128                 if (!$spoofable) {
 129                         $result['header_valid'] = true;
 130                 }
 131
 132                 return $result;
 133         }
 134
 135         /**
 136          * @param array   $head
 137          * @param string  $prvkey
 138          * @param string  $keyid (optional, default 'Key')
 139          *
 140          * @return array
 141          */
 142         public static function createSig(array $head, string $prvkey, string $keyid = 'Key'): array
 143         {
 144                 $return_headers = [];
 145                 if (!empty($head)) {
 146                         $return_headers = $head;
 147                 }
 148
 149                 $alg = 'sha512';
 150                 $algorithm = 'rsa-sha512';
 151
 152                 $x = self::sign($head, $prvkey, $alg);
 153
 154                 $headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
 155                         . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
 156
 157                 $return_headers['Authorization'] = ['Signature ' . $headerval];
 158
 159                 return $return_headers;
 160         }
 161
 162         /**
 163          * @param array  $head
 164          * @param string $prvkey
 165          * @param string $alg (optional) default 'sha256'
 166          *
 167          * @return array
 168          */
 169         private static function sign(array $head, string $prvkey, string $alg = 'sha256'): array
 170         {
 171                 $ret = [];
 172                 $headers = '';
 173                 $fields  = '';
 174
 175                 foreach ($head as $k => $v) {
 176                         if (is_array($v)) {
 177                                 $v = implode(', ', $v);
 178                         }
 179                         $headers .= strtolower($k) . ': ' . trim($v) . "\n";
 180                         if ($fields) {
 181                                 $fields .= ' ';
 182                         }
 183                         $fields .= strtolower($k);
 184                 }
 185                 // strip the trailing linefeed
 186                 $headers = rtrim($headers, "\n");
 187
 188                 $sig = base64_encode(Crypto::rsaSign($headers, $prvkey, $alg));
 189
 190                 $ret['headers']   = $fields;
 191                 $ret['signature'] = $sig;
 192
 193                 return $ret;
 194         }
 195
 196         /**
 197          * @param string $header
 198          * @return array associative array with
 199          *   - \e string \b keyID
 200          *   - \e string \b created
 201          *   - \e string \b expires
 202          *   - \e string \b algorithm
 203          *   - \e array  \b headers
 204          *   - \e string \b signature
 205          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 206          */
 207         public static function parseSigheader(string $header): array
 208         {
 209                 // Remove obsolete folds
 210                 $header = preg_replace('/\n\s+/', ' ', $header);
 211
 212                 $token = "[!#$%&'*+.^_`|~0-9A-Za-z-]";
 213
 214                 $quotedString = '"(?:\\\\.|[^"\\\\])*"';
 215
 216                 $regex = "/($token+)=($quotedString|$token+)/ism";
 217
 218                 $matches = [];
 219                 preg_match_all($regex, $header, $matches, PREG_SET_ORDER);
 220
 221                 $headers = [];
 222                 foreach ($matches as $match) {
 223                         $headers[$match[1]] = trim($match[2] ?: $match[3], '"');
 224                 }
 225
 226                 // if the header is encrypted, decrypt with (default) site private key and continue
 227                 if (!empty($headers['iv'])) {
 228                         $header = self::decryptSigheader($headers, DI::config()->get('system', 'prvkey'));
 229                         return self::parseSigheader($header);
 230                 }
 231
 232                 $return = [
 233                         'keyId'     => $headers['keyId'] ?? '',
 234                         'algorithm' => $headers['algorithm'] ?? 'rsa-sha256',
 235                         'created'   => $headers['created'] ?? null,
 236                         'expires'   => $headers['expires'] ?? null,
 237                         'headers'   => explode(' ', $headers['headers'] ?? ''),
 238                         'signature' => base64_decode(preg_replace('/\s+/', '', $headers['signature'] ?? '')),
 239                 ];
 240
 241                 if (!empty($return['signature']) && !empty($return['algorithm']) && empty($return['headers'])) {
 242                         $return['headers'] = ['date'];
 243                 }
 244
 245                 return $return;
 246         }
 247
 248         /**
 249          * @param array  $headers Signature headers
 250          * @param string $prvkey  The site private key
 251          * @return string Decrypted signature string
 252          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 253          */
 254         private static function decryptSigheader(array $headers, string $prvkey): string
 255         {
 256                 if (!empty($headers['iv']) && !empty($headers['key']) && !empty($headers['data'])) {
 257                         return Crypto::unencapsulate($headers, $prvkey);
 258                 }
 259
 260                 return '';
 261         }
 262
 263         /*
 264          * Functions for ActivityPub
 265          */
 266
 267         /**
 268          * Post given data to a target for a user, returns the result class
 269          *
 270          * @param array  $data   Data that is about to be sent
 271          * @param string $target The URL of the inbox
 272          * @param array  $owner  Sender owner-view record
 273          *
 274          * @return ICanHandleHttpResponses
 275          */
 276         public static function post(array $data, string $target, array $owner): ICanHandleHttpResponses
 277         {
 278                 $content = json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
 279
 280                 // Header data that is about to be signed.
 281                 $host = parse_url($target, PHP_URL_HOST);
 282                 $path = parse_url($target, PHP_URL_PATH);
 283                 $digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
 284                 $content_length = strlen($content);
 285                 $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 286
 287                 $headers = [
 288                         'Date' => $date,
 289                         'Content-Length' => $content_length,
 290                         'Digest' => $digest,
 291                         'Host' => $host
 292                 ];
 293
 294                 $signed_data = "(request-target): post " . $path . "\ndate: ". $date . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
 295
 296                 $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 297
 298                 $headers['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date content-length digest host",signature="' . $signature . '"';
 299
 300                 $headers['Content-Type'] = 'application/activity+json';
 301
 302                 $postResult = DI::httpClient()->post($target, $content, $headers, DI::config()->get('system', 'curl_timeout'));
 303                 $return_code = $postResult->getReturnCode();
 304
 305                 Logger::info('Transmit to ' . $target . ' returned ' . $return_code);
 306
 307                 self::setInboxStatus($target, ($return_code >= 200) && ($return_code <= 299));
 308
 309                 return $postResult;
 310         }
 311
 312         /**
 313          * Transmit given data to a target for a user
 314          *
 315          * @param array  $data   Data that is about to be sent
 316          * @param string $target The URL of the inbox
 317          * @param array  $owner  Sender owner-vew record
 318          *
 319          * @return boolean Was the transmission successful?
 320          */
 321         public static function transmit(array $data, string $target, array $owner): bool
 322         {
 323                 $postResult = self::post($data, $target, $owner);
 324                 $return_code = $postResult->getReturnCode();
 325
 326                 return ($return_code >= 200) && ($return_code <= 299);
 327         }
 328
 329         /**
 330          * Set the delivery status for a given inbox
 331          *
 332          * @param string  $url     The URL of the inbox
 333          * @param boolean $success Transmission status
 334          * @param boolean $shared  The inbox is a shared inbox
 335          * @param int     $gsid    Server ID
 336          * @throws \Exception
 337          */
 338         static public function setInboxStatus(string $url, bool $success, bool $shared = false, int $gsid = null)
 339         {
 340                 $now = DateTimeFormat::utcNow();
 341
 342                 $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 343                 if (!DBA::isResult($status)) {
 344                         $insertFields = ['url' => $url, 'uri-id' => ItemURI::getIdByURI($url), 'created' => $now, 'shared' => $shared];
 345                         if (!empty($gsid)) {
 346                                 $insertFields['gsid'] = $gsid;
 347                         }
 348                         if (!DBA::insert('inbox-status', $insertFields, Database::INSERT_IGNORE)) {
 349                                 Logger::warning('Unable to insert inbox-status row', $insertFields);
 350                                 return;
 351                         }
 352
 353                         $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 354                 }
 355
 356                 if ($success) {
 357                         $fields = ['success' => $now];
 358                 } else {
 359                         $fields = ['failure' => $now];
 360                 }
 361
 362                 if (!empty($gsid)) {
 363                         $fields['gsid'] = $gsid;
 364                 }
 365
 366                 if ($status['failure'] > DBA::NULL_DATETIME) {
 367                         $new_previous_stamp = strtotime($status['failure']);
 368                         $old_previous_stamp = strtotime($status['previous']);
 369
 370                         // Only set "previous" with at least one day difference.
 371                         // We use this to assure to not accidentally archive too soon.
 372                         if (($new_previous_stamp - $old_previous_stamp) >= 86400) {
 373                                 $fields['previous'] = $status['failure'];
 374                         }
 375                 }
 376
 377                 if (!$success) {
 378                         if ($status['success'] <= DBA::NULL_DATETIME) {
 379                                 $stamp1 = strtotime($status['created']);
 380                         } else {
 381                                 $stamp1 = strtotime($status['success']);
 382                         }
 383
 384                         $stamp2 = strtotime($now);
 385                         $previous_stamp = strtotime($status['previous']);
 386
 387                         // Archive the inbox when there had been failures for five days.
 388                         // Additionally ensure that at least one previous attempt has to be in between.
 389                         if ((($stamp2 - $stamp1) >= 86400 * 5) && ($previous_stamp > $stamp1)) {
 390                                 $fields['archive'] = true;
 391                         }
 392                 } else {
 393                         $fields['archive'] = false;
 394                 }
 395
 396                 if (empty($status['uri-id'])) {
 397                         $fields['uri-id'] = ItemURI::getIdByURI($url);
 398                 }
 399
 400                 DBA::update('inbox-status', $fields, ['url' => $url]);
 401         }
 402
 403         /**
 404          * Fetches JSON data for a user
 405          *
 406          * @param string  $request request url
 407          * @param integer $uid     User id of the requester
 408          *
 409          * @return array JSON array
 410          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 411          */
 412         public static function fetch(string $request, int $uid): array
 413         {
 414                 $curlResult = self::fetchRaw($request, $uid);
 415
 416                 if (empty($curlResult)) {
 417                         return [];
 418                 }
 419
 420                 if (!$curlResult->isSuccess() || empty($curlResult->getBody())) {
 421                         return [];
 422                 }
 423
 424                 $content = json_decode($curlResult->getBody(), true);
 425                 if (empty($content) || !is_array($content)) {
 426                         return [];
 427                 }
 428
 429                 return $content;
 430         }
 431
 432         /**
 433          * Fetches raw data for a user
 434          *
 435          * @param string  $request request url
 436          * @param integer $uid     User id of the requester
 437          * @param boolean $binary  TRUE if asked to return binary results (file download) (default is "false")
 438          * @param array   $opts    (optional parameters) assoziative array with:
 439          *                         'accept_content' => supply Accept: header with 'accept_content' as the value
 440          *                         'timeout' => int Timeout in seconds, default system config value or 60 seconds
 441          *                         'nobody' => only return the header
 442          *                         'cookiejar' => path to cookie jar file
 443          *
 444          * @return \Friendica\Network\HTTPClient\Capability\ICanHandleHttpResponses CurlResult
 445          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 446          */
 447         public static function fetchRaw(string $request, int $uid = 0, array $opts = [HttpClientOptions::ACCEPT_CONTENT => [HttpClientAccept::JSON_AS]])
 448         {
 449                 $header = [];
 450
 451                 if (!empty($uid)) {
 452                         $owner = User::getOwnerDataById($uid);
 453                         if (!$owner) {
 454                                 return;
 455                         }
 456                 } else {
 457                         $owner = User::getSystemAccount();
 458                         if (!$owner) {
 459                                 return;
 460                         }
 461                 }
 462
 463                 if (!empty($owner['uprvkey'])) {
 464                         // Header data that is about to be signed.
 465                         $host = parse_url($request, PHP_URL_HOST);
 466                         $path = parse_url($request, PHP_URL_PATH);
 467                         $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 468
 469                         $header['Date'] = $date;
 470                         $header['Host'] = $host;
 471
 472                         $signed_data = "(request-target): get " . $path . "\ndate: ". $date . "\nhost: " . $host;
 473
 474                         $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 475
 476                         $header['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date host",signature="' . $signature . '"';
 477                 }
 478
 479                 $curl_opts                             = $opts;
 480                 $curl_opts[HttpClientOptions::HEADERS] = $header;
 481
 482                 if (!empty($opts['nobody'])) {
 483                         $curlResult = DI::httpClient()->head($request, $curl_opts);
 484                 } else {
 485                         $curlResult = DI::httpClient()->get($request, HttpClientAccept::JSON_AS, $curl_opts);
 486                 }
 487                 $return_code = $curlResult->getReturnCode();
 488
 489                 Logger::info('Fetched for user ' . $uid . ' from ' . $request . ' returned ' . $return_code);
 490
 491                 return $curlResult;
 492         }
 493
 494         /**
 495          * Fetch the apcontact entry of the keyId in the given header
 496          *
 497          * @param array $http_headers
 498          *
 499          * @return array APContact entry
 500          */
 501         public static function getKeyIdContact(array $http_headers): array
 502         {
 503                 if (empty($http_headers['HTTP_SIGNATURE'])) {
 504                         Logger::debug('No HTTP_SIGNATURE header', ['header' => $http_headers]);
 505                         return [];
 506                 }
 507
 508                 $sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 509
 510                 if (empty($sig_block['keyId'])) {
 511                         Logger::debug('No keyId', ['sig_block' => $sig_block]);
 512                         return [];
 513                 }
 514
 515                 $url = (strpos($sig_block['keyId'], '#') ? substr($sig_block['keyId'], 0, strpos($sig_block['keyId'], '#')) : $sig_block['keyId']);
 516                 return APContact::getByURL($url);
 517         }
 518
 519         /**
 520          * Gets a signer from a given HTTP request
 521          *
 522          * @param string $content
 523          * @param array $http_headers
 524          *
 525          * @return string|null|false Signer
 526          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 527          */
 528         public static function getSigner(string $content, array $http_headers)
 529         {
 530                 if (empty($http_headers['HTTP_SIGNATURE'])) {
 531                         Logger::debug('No HTTP_SIGNATURE header');
 532                         return false;
 533                 }
 534
 535                 if (!empty($content)) {
 536                         $object = json_decode($content, true);
 537                         if (empty($object)) {
 538                                 Logger::info('No object');
 539                                 return false;
 540                         }
 541
 542                         $actor = JsonLD::fetchElement($object, 'actor', 'id') ?? '';
 543                 } else {
 544                         $actor = '';
 545                 }
 546
 547                 $headers = [];
 548                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()) . ' ' . parse_url($http_headers['REQUEST_URI'], PHP_URL_PATH);
 549
 550                 // First take every header
 551                 foreach ($http_headers as $k => $v) {
 552                         $field = str_replace('_', '-', strtolower($k));
 553                         $headers[$field] = $v;
 554                 }
 555
 556                 // Now add every http header
 557                 foreach ($http_headers as $k => $v) {
 558                         if (strpos($k, 'HTTP_') === 0) {
 559                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
 560                                 $headers[$field] = $v;
 561                         }
 562                 }
 563
 564                 $sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 565
 566                 // Add fields from the signature block to the header. See issue 8845
 567                 if (!empty($sig_block['created']) && empty($headers['(created)'])) {
 568                         $headers['(created)'] = $sig_block['created'];
 569                 }
 570
 571                 if (!empty($sig_block['expires']) && empty($headers['(expires)'])) {
 572                         $headers['(expires)'] = $sig_block['expires'];
 573                 }
 574
 575                 if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
 576                         Logger::info('No headers or keyId');
 577                         return false;
 578                 }
 579
 580                 $signed_data = '';
 581                 foreach ($sig_block['headers'] as $h) {
 582                         if (array_key_exists($h, $headers)) {
 583                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 584                         } else {
 585                                 Logger::info('Requested header field not found', ['field' => $h, 'header' => $headers]);
 586                         }
 587                 }
 588                 $signed_data = rtrim($signed_data, "\n");
 589
 590                 if (empty($signed_data)) {
 591                         Logger::info('Signed data is empty');
 592                         return false;
 593                 }
 594
 595                 $algorithm = null;
 596
 597                 // Wildcard value where signing algorithm should be derived from keyId
 598                 // @see https://tools.ietf.org/html/draft-ietf-httpbis-message-signatures-00#section-4.1
 599                 // Defaulting to SHA256 as it seems to be the prevalent implementation
 600                 // @see https://arewehs2019yet.vpzom.click
 601                 if ($sig_block['algorithm'] === 'hs2019') {
 602                         $algorithm = 'sha256';
 603                 }
 604
 605                 if ($sig_block['algorithm'] === 'rsa-sha256') {
 606                         $algorithm = 'sha256';
 607                 }
 608
 609                 if ($sig_block['algorithm'] === 'rsa-sha512') {
 610                         $algorithm = 'sha512';
 611                 }
 612
 613                 if (empty($algorithm)) {
 614                         Logger::info('No alagorithm');
 615                         return false;
 616                 }
 617
 618                 $key = self::fetchKey($sig_block['keyId'], $actor);
 619                 if (empty($key)) {
 620                         Logger::info('Empty key');
 621                         return false;
 622                 }
 623
 624                 if (!empty($key['url']) && !empty($key['type']) && ($key['type'] == 'Tombstone')) {
 625                         Logger::info('Actor is a tombstone', ['key' => $key]);
 626
 627                         if (!Contact::isLocal($key['url'])) {
 628                                 // We now delete everything that we possibly knew from this actor
 629                                 Contact::deleteContactByUrl($key['url']);
 630                         }
 631                         return null;
 632                 }
 633
 634                 if (empty($key['pubkey'])) {
 635                         Logger::info('Empty pubkey');
 636                         return false;
 637                 }
 638
 639                 if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key['pubkey'], $algorithm)) {
 640                         Logger::info('Verification failed', ['signed_data' => $signed_data, 'algorithm' => $algorithm, 'header' => $sig_block['headers'], 'http_headers' => $http_headers]);
 641                         return false;
 642                 }
 643
 644                 $hasGoodSignedContent = false;
 645
 646                 // Check the digest when it is part of the signed data
 647                 if (!empty($content) && in_array('digest', $sig_block['headers'])) {
 648                         $digest = explode('=', $headers['digest'], 2);
 649                         if ($digest[0] === 'SHA-256') {
 650                                 $hashalg = 'sha256';
 651                         }
 652                         if ($digest[0] === 'SHA-512') {
 653                                 $hashalg = 'sha512';
 654                         }
 655
 656                         /// @todo add all hashes from the rfc
 657
 658                         if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
 659                                 Logger::info('Digest does not match');
 660                                 return false;
 661                         }
 662
 663                         $hasGoodSignedContent = true;
 664                 }
 665
 666                 if (in_array('date', $sig_block['headers']) && !empty($headers['date'])) {
 667                         $created = strtotime($headers['date']);
 668                 } elseif (in_array('(created)', $sig_block['headers']) && !empty($sig_block['created'])) {
 669                         $created = $sig_block['created'];
 670                 } else {
 671                         $created = 0;
 672                 }
 673
 674                 if (in_array('(expires)', $sig_block['headers']) && !empty($sig_block['expires'])) {
 675                         $expired = min($sig_block['expires'], $created + 300);
 676                 } else {
 677                         $expired = $created + 300;
 678                 }
 679
 680                 //  Check if the signed date field is in an acceptable range
 681                 if (!empty($created)) {
 682                         $current = time();
 683
 684                         // Calculate with a grace period of 60 seconds to avoid slight time differences between the servers
 685                         if (($created - 60) > $current) {
 686                                 Logger::notice('Signature created in the future', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 687                                 return false;
 688                         }
 689
 690                         if ($current > $expired) {
 691                                 Logger::notice('Signature expired', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 692                                 return false;
 693                         }
 694
 695                         Logger::debug('Valid creation date', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 696                         $hasGoodSignedContent = true;
 697                 }
 698
 699                 // Check the content-length when it is part of the signed data
 700                 if (in_array('content-length', $sig_block['headers'])) {
 701                         if (strlen($content) != $headers['content-length']) {
 702                                 Logger::info('Content length does not match');
 703                                 return false;
 704                         }
 705                 }
 706
 707                 // Ensure that the authentication had been done with some content
 708                 // Without this check someone could authenticate with fakeable data
 709                 if (!$hasGoodSignedContent) {
 710                         Logger::info('No good signed content');
 711                         return false;
 712                 }
 713
 714                 return $key['url'];
 715         }
 716
 717         /**
 718          * fetches a key for a given id and actor
 719          *
 720          * @param string $id
 721          * @param string $actor
 722          *
 723          * @return array with actor url and public key
 724          * @throws \Exception
 725          */
 726         private static function fetchKey(string $id, string $actor): array
 727         {
 728                 $url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
 729
 730                 $profile = APContact::getByURL($url);
 731                 if (!empty($profile)) {
 732                         Logger::info('Taking key from id', ['id' => $id]);
 733                         return ['url' => $url, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 734                 } elseif ($url != $actor) {
 735                         $profile = APContact::getByURL($actor);
 736                         if (!empty($profile)) {
 737                                 Logger::info('Taking key from actor', ['actor' => $actor]);
 738                                 return ['url' => $actor, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 739                         }
 740                 }
 741
 742                 Logger::notice('Key could not be fetched', ['url' => $url, 'actor' => $actor]);
 743                 return [];
 744         }
 745 }