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\Core\Protocol;
  26 use Friendica\Database\Database;
  27 use Friendica\Database\DBA;
  28 use Friendica\DI;
  29 use Friendica\Model\APContact;
  30 use Friendica\Model\Contact;
  31 use Friendica\Model\GServer;
  32 use Friendica\Model\ItemURI;
  33 use Friendica\Model\User;
  34 use Friendica\Network\HTTPClient\Capability\ICanHandleHttpResponses;
  35 use Friendica\Network\HTTPClient\Client\HttpClientAccept;
  36 use Friendica\Network\HTTPClient\Client\HttpClientOptions;
  37
  38 /**
  39  * Implements HTTP Signatures per draft-cavage-http-signatures-07.
  40  *
  41  * Ported from Hubzilla: https://framagit.org/hubzilla/core/blob/master/Zotlabs/Web/HTTPSig.php
  42  *
  43  * Other parts of the code for HTTP signing are taken from the Osada project.
  44  * https://framagit.org/macgirvin/osada
  45  *
  46  * @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
  47  */
  48
  49 class HTTPSignature
  50 {
  51         // See draft-cavage-http-signatures-08
  52         /**
  53          * Verifies a magic request
  54          *
  55          * @param $key
  56          *
  57          * @return array with verification data
  58          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
  59          */
  60         public static function verifyMagic(string $key): array
  61         {
  62                 $headers   = null;
  63                 $spoofable = false;
  64                 $result = [
  65                         'signer'         => '',
  66                         'header_signed'  => false,
  67                         'header_valid'   => false
  68                 ];
  69
  70                 // Decide if $data arrived via controller submission or curl.
  71                 $headers = [];
  72                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()).' '.$_SERVER['REQUEST_URI'];
  73
  74                 foreach ($_SERVER as $k => $v) {
  75                         if (strpos($k, 'HTTP_') === 0) {
  76                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
  77                                 $headers[$field] = $v;
  78                         }
  79                 }
  80
  81                 $sig_block = null;
  82
  83                 $sig_block = self::parseSigheader($headers['authorization']);
  84
  85                 if (!$sig_block) {
  86                         Logger::notice('no signature provided.');
  87                         return $result;
  88                 }
  89
  90                 $result['header_signed'] = true;
  91
  92                 $signed_headers = $sig_block['headers'];
  93                 if (!$signed_headers) {
  94                         $signed_headers = ['date'];
  95                 }
  96
  97                 $signed_data = '';
  98                 foreach ($signed_headers as $h) {
  99                         if (array_key_exists($h, $headers)) {
 100                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 101                         }
 102                         if (strpos($h, '.')) {
 103                                 $spoofable = true;
 104                         }
 105                 }
 106
 107                 $signed_data = rtrim($signed_data, "\n");
 108
 109                 $algorithm = 'sha512';
 110
 111                 if ($key && function_exists($key)) {
 112                         $result['signer'] = $sig_block['keyId'];
 113                         $key = $key($sig_block['keyId']);
 114                 }
 115
 116                 Logger::info('Got keyID ' . $sig_block['keyId']);
 117
 118                 if (!$key) {
 119                         return $result;
 120                 }
 121
 122                 $x = Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm);
 123
 124                 Logger::info('verified: ' . $x);
 125
 126                 if (!$x) {
 127                         return $result;
 128                 }
 129
 130                 if (!$spoofable) {
 131                         $result['header_valid'] = true;
 132                 }
 133
 134                 return $result;
 135         }
 136
 137         /**
 138          * @param array   $head
 139          * @param string  $prvkey
 140          * @param string  $keyid (optional, default 'Key')
 141          *
 142          * @return array
 143          */
 144         public static function createSig(array $head, string $prvkey, string $keyid = 'Key'): array
 145         {
 146                 $return_headers = [];
 147                 if (!empty($head)) {
 148                         $return_headers = $head;
 149                 }
 150
 151                 $alg = 'sha512';
 152                 $algorithm = 'rsa-sha512';
 153
 154                 $x = self::sign($head, $prvkey, $alg);
 155
 156                 $headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
 157                         . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
 158
 159                 $return_headers['Authorization'] = ['Signature ' . $headerval];
 160
 161                 return $return_headers;
 162         }
 163
 164         /**
 165          * @param array  $head
 166          * @param string $prvkey
 167          * @param string $alg (optional) default 'sha256'
 168          *
 169          * @return array
 170          */
 171         private static function sign(array $head, string $prvkey, string $alg = 'sha256'): array
 172         {
 173                 $ret = [];
 174                 $headers = '';
 175                 $fields  = '';
 176
 177                 foreach ($head as $k => $v) {
 178                         if (is_array($v)) {
 179                                 $v = implode(', ', $v);
 180                         }
 181                         $headers .= strtolower($k) . ': ' . trim($v) . "\n";
 182                         if ($fields) {
 183                                 $fields .= ' ';
 184                         }
 185                         $fields .= strtolower($k);
 186                 }
 187                 // strip the trailing linefeed
 188                 $headers = rtrim($headers, "\n");
 189
 190                 $sig = base64_encode(Crypto::rsaSign($headers, $prvkey, $alg));
 191
 192                 $ret['headers']   = $fields;
 193                 $ret['signature'] = $sig;
 194
 195                 return $ret;
 196         }
 197
 198         /**
 199          * @param string $header
 200          * @return array associative array with
 201          *   - \e string \b keyID
 202          *   - \e string \b created
 203          *   - \e string \b expires
 204          *   - \e string \b algorithm
 205          *   - \e array  \b headers
 206          *   - \e string \b signature
 207          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 208          */
 209         public static function parseSigheader(string $header): array
 210         {
 211                 // Remove obsolete folds
 212                 $header = preg_replace('/\n\s+/', ' ', $header);
 213
 214                 $token = "[!#$%&'*+.^_`|~0-9A-Za-z-]";
 215
 216                 $quotedString = '"(?:\\\\.|[^"\\\\])*"';
 217
 218                 $regex = "/($token+)=($quotedString|$token+)/ism";
 219
 220                 $matches = [];
 221                 preg_match_all($regex, $header, $matches, PREG_SET_ORDER);
 222
 223                 $headers = [];
 224                 foreach ($matches as $match) {
 225                         $headers[$match[1]] = trim($match[2] ?: $match[3], '"');
 226                 }
 227
 228                 // if the header is encrypted, decrypt with (default) site private key and continue
 229                 if (!empty($headers['iv'])) {
 230                         $header = self::decryptSigheader($headers, DI::config()->get('system', 'prvkey'));
 231                         return self::parseSigheader($header);
 232                 }
 233
 234                 $return = [
 235                         'keyId'     => $headers['keyId'] ?? '',
 236                         'algorithm' => $headers['algorithm'] ?? 'rsa-sha256',
 237                         'created'   => $headers['created'] ?? null,
 238                         'expires'   => $headers['expires'] ?? null,
 239                         'headers'   => explode(' ', $headers['headers'] ?? ''),
 240                         'signature' => base64_decode(preg_replace('/\s+/', '', $headers['signature'] ?? '')),
 241                 ];
 242
 243                 if (!empty($return['signature']) && !empty($return['algorithm']) && empty($return['headers'])) {
 244                         $return['headers'] = ['date'];
 245                 }
 246
 247                 return $return;
 248         }
 249
 250         /**
 251          * @param array  $headers Signature headers
 252          * @param string $prvkey  The site private key
 253          * @return string Decrypted signature string
 254          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 255          */
 256         private static function decryptSigheader(array $headers, string $prvkey): string
 257         {
 258                 if (!empty($headers['iv']) && !empty($headers['key']) && !empty($headers['data'])) {
 259                         return Crypto::unencapsulate($headers, $prvkey);
 260                 }
 261
 262                 return '';
 263         }
 264
 265         /*
 266          * Functions for ActivityPub
 267          */
 268
 269         /**
 270          * Post given data to a target for a user, returns the result class
 271          *
 272          * @param array  $data   Data that is about to be sent
 273          * @param string $target The URL of the inbox
 274          * @param array  $owner  Sender owner-view record
 275          *
 276          * @return ICanHandleHttpResponses
 277          */
 278         public static function post(array $data, string $target, array $owner): ICanHandleHttpResponses
 279         {
 280                 $content = json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
 281
 282                 // Header data that is about to be signed.
 283                 $host = parse_url($target, PHP_URL_HOST);
 284                 $path = parse_url($target, PHP_URL_PATH);
 285                 $digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
 286                 $content_length = strlen($content);
 287                 $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 288
 289                 $headers = [
 290                         'Date' => $date,
 291                         'Content-Length' => $content_length,
 292                         'Digest' => $digest,
 293                         'Host' => $host
 294                 ];
 295
 296                 $signed_data = "(request-target): post " . $path . "\ndate: ". $date . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
 297
 298                 $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 299
 300                 $headers['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date content-length digest host",signature="' . $signature . '"';
 301
 302                 $headers['Content-Type'] = 'application/activity+json';
 303
 304                 $postResult = DI::httpClient()->post($target, $content, $headers, DI::config()->get('system', 'curl_timeout'));
 305                 $return_code = $postResult->getReturnCode();
 306
 307                 Logger::info('Transmit to ' . $target . ' returned ' . $return_code);
 308
 309                 self::setInboxStatus($target, ($return_code >= 200) && ($return_code <= 299));
 310
 311                 return $postResult;
 312         }
 313
 314         /**
 315          * Transmit given data to a target for a user
 316          *
 317          * @param array  $data   Data that is about to be sent
 318          * @param string $target The URL of the inbox
 319          * @param array  $owner  Sender owner-vew record
 320          *
 321          * @return boolean Was the transmission successful?
 322          */
 323         public static function transmit(array $data, string $target, array $owner): bool
 324         {
 325                 $postResult = self::post($data, $target, $owner);
 326                 $return_code = $postResult->getReturnCode();
 327
 328                 return ($return_code >= 200) && ($return_code <= 299);
 329         }
 330
 331         /**
 332          * Set the delivery status for a given inbox
 333          *
 334          * @param string  $url     The URL of the inbox
 335          * @param boolean $success Transmission status
 336          * @param boolean $shared  The inbox is a shared inbox
 337          * @param int     $gsid    Server ID
 338          * @throws \Exception
 339          */
 340         static public function setInboxStatus(string $url, bool $success, bool $shared = false, int $gsid = null)
 341         {
 342                 $now = DateTimeFormat::utcNow();
 343
 344                 $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 345                 if (!DBA::isResult($status)) {
 346                         $insertFields = ['url' => $url, 'uri-id' => ItemURI::getIdByURI($url), 'created' => $now, 'shared' => $shared];
 347                         if (!empty($gsid)) {
 348                                 $insertFields['gsid'] = $gsid;
 349                         }
 350                         DBA::insert('inbox-status', $insertFields, Database::INSERT_IGNORE);
 351
 352                         $status = DBA::selectFirst('inbox-status', [], ['url' => $url]);
 353                         if (empty($status)) {
 354                                 Logger::warning('Unable to insert inbox-status row', $insertFields);
 355                                 return;
 356                         }
 357                 }
 358
 359                 if ($success) {
 360                         $fields = ['success' => $now];
 361                 } else {
 362                         $fields = ['failure' => $now];
 363                 }
 364
 365                 if (!empty($gsid)) {
 366                         $fields['gsid'] = $gsid;
 367                 }
 368
 369                 if ($status['failure'] > DBA::NULL_DATETIME) {
 370                         $new_previous_stamp = strtotime($status['failure']);
 371                         $old_previous_stamp = strtotime($status['previous']);
 372
 373                         // Only set "previous" with at least one day difference.
 374                         // We use this to assure to not accidentally archive too soon.
 375                         if (($new_previous_stamp - $old_previous_stamp) >= 86400) {
 376                                 $fields['previous'] = $status['failure'];
 377                         }
 378                 }
 379
 380                 if (!$success) {
 381                         if ($status['success'] <= DBA::NULL_DATETIME) {
 382                                 $stamp1 = strtotime($status['created']);
 383                         } else {
 384                                 $stamp1 = strtotime($status['success']);
 385                         }
 386
 387                         $stamp2 = strtotime($now);
 388                         $previous_stamp = strtotime($status['previous']);
 389
 390                         // Archive the inbox when there had been failures for five days.
 391                         // Additionally ensure that at least one previous attempt has to be in between.
 392                         if ((($stamp2 - $stamp1) >= 86400 * 5) && ($previous_stamp > $stamp1)) {
 393                                 $fields['archive'] = true;
 394                         }
 395                 } else {
 396                         $fields['archive'] = false;
 397                 }
 398
 399                 if (empty($status['uri-id'])) {
 400                         $fields['uri-id'] = ItemURI::getIdByURI($url);
 401                 }
 402
 403                 DBA::update('inbox-status', $fields, ['url' => $url]);
 404
 405                 if (!empty($status['gsid'])) {
 406                         if ($success) {
 407                                 GServer::setReachableById($status['gsid'], Protocol::ACTIVITYPUB);
 408                         } elseif ($status['shared']) {
 409                                 GServer::setFailureById($status['gsid']);
 410                         }
 411                 }
 412         }
 413
 414         /**
 415          * Fetches JSON data for a user
 416          *
 417          * @param string  $request request url
 418          * @param integer $uid     User id of the requester
 419          *
 420          * @return array JSON array
 421          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 422          */
 423         public static function fetch(string $request, int $uid): array
 424         {
 425                 try {
 426                         $curlResult = self::fetchRaw($request, $uid);
 427                 } catch (\Exception $exception) {
 428                         Logger::notice('Error fetching url', ['url' => $request, 'exception' => $exception]);
 429                         return [];
 430                 }
 431
 432                 if (empty($curlResult)) {
 433                         return [];
 434                 }
 435
 436                 if (!$curlResult->isSuccess() || empty($curlResult->getBody())) {
 437                         return [];
 438                 }
 439
 440                 $content = json_decode($curlResult->getBody(), true);
 441                 if (empty($content) || !is_array($content)) {
 442                         return [];
 443                 }
 444
 445                 return $content;
 446         }
 447
 448         /**
 449          * Fetches raw data for a user
 450          *
 451          * @param string  $request request url
 452          * @param integer $uid     User id of the requester
 453          * @param boolean $binary  TRUE if asked to return binary results (file download) (default is "false")
 454          * @param array   $opts    (optional parameters) associative array with:
 455          *                         'accept_content' => supply Accept: header with 'accept_content' as the value
 456          *                         'timeout' => int Timeout in seconds, default system config value or 60 seconds
 457          *                         'nobody' => only return the header
 458          *                         'cookiejar' => path to cookie jar file
 459          *
 460          * @return \Friendica\Network\HTTPClient\Capability\ICanHandleHttpResponses CurlResult
 461          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 462          */
 463         public static function fetchRaw(string $request, int $uid = 0, array $opts = [HttpClientOptions::ACCEPT_CONTENT => [HttpClientAccept::JSON_AS]])
 464         {
 465                 $header = [];
 466
 467                 if (!empty($uid)) {
 468                         $owner = User::getOwnerDataById($uid);
 469                         if (!$owner) {
 470                                 return;
 471                         }
 472                 } else {
 473                         $owner = User::getSystemAccount();
 474                         if (!$owner) {
 475                                 return;
 476                         }
 477                 }
 478
 479                 if (!empty($owner['uprvkey'])) {
 480                         // Header data that is about to be signed.
 481                         $host = parse_url($request, PHP_URL_HOST);
 482                         $path = parse_url($request, PHP_URL_PATH);
 483                         $date = DateTimeFormat::utcNow(DateTimeFormat::HTTP);
 484
 485                         $header['Date'] = $date;
 486                         $header['Host'] = $host;
 487
 488                         $signed_data = "(request-target): get " . $path . "\ndate: ". $date . "\nhost: " . $host;
 489
 490                         $signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
 491
 492                         $header['Signature'] = 'keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) date host",signature="' . $signature . '"';
 493                 }
 494
 495                 $curl_opts                             = $opts;
 496                 $curl_opts[HttpClientOptions::HEADERS] = $header;
 497
 498                 if (!empty($opts['nobody'])) {
 499                         $curlResult = DI::httpClient()->head($request, $curl_opts);
 500                 } else {
 501                         $curlResult = DI::httpClient()->get($request, HttpClientAccept::JSON_AS, $curl_opts);
 502                 }
 503                 $return_code = $curlResult->getReturnCode();
 504
 505                 Logger::info('Fetched for user ' . $uid . ' from ' . $request . ' returned ' . $return_code);
 506
 507                 return $curlResult;
 508         }
 509
 510         /**
 511          * Fetch the apcontact entry of the keyId in the given header
 512          *
 513          * @param array $http_headers
 514          *
 515          * @return array APContact entry
 516          */
 517         public static function getKeyIdContact(array $http_headers): array
 518         {
 519                 if (empty($http_headers['HTTP_SIGNATURE'])) {
 520                         Logger::debug('No HTTP_SIGNATURE header', ['header' => $http_headers]);
 521                         return [];
 522                 }
 523
 524                 $sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 525
 526                 if (empty($sig_block['keyId'])) {
 527                         Logger::debug('No keyId', ['sig_block' => $sig_block]);
 528                         return [];
 529                 }
 530
 531                 $url = (strpos($sig_block['keyId'], '#') ? substr($sig_block['keyId'], 0, strpos($sig_block['keyId'], '#')) : $sig_block['keyId']);
 532                 return APContact::getByURL($url);
 533         }
 534
 535         /**
 536          * Gets a signer from a given HTTP request
 537          *
 538          * @param string $content
 539          * @param array $http_headers
 540          *
 541          * @return string|null|false Signer
 542          * @throws \Friendica\Network\HTTPException\InternalServerErrorException
 543          */
 544         public static function getSigner(string $content, array $http_headers)
 545         {
 546                 if (empty($http_headers['HTTP_SIGNATURE'])) {
 547                         Logger::debug('No HTTP_SIGNATURE header');
 548                         return false;
 549                 }
 550
 551                 if (!empty($content)) {
 552                         $object = json_decode($content, true);
 553                         if (empty($object)) {
 554                                 Logger::info('No object');
 555                                 return false;
 556                         }
 557
 558                         $actor = JsonLD::fetchElement($object, 'actor', 'id') ?? '';
 559                 } else {
 560                         $actor = '';
 561                 }
 562
 563                 $headers = [];
 564                 $headers['(request-target)'] = strtolower(DI::args()->getMethod()) . ' ' . parse_url($http_headers['REQUEST_URI'], PHP_URL_PATH);
 565
 566                 // First take every header
 567                 foreach ($http_headers as $k => $v) {
 568                         $field = str_replace('_', '-', strtolower($k));
 569                         $headers[$field] = $v;
 570                 }
 571
 572                 // Now add every http header
 573                 foreach ($http_headers as $k => $v) {
 574                         if (strpos($k, 'HTTP_') === 0) {
 575                                 $field = str_replace('_', '-', strtolower(substr($k, 5)));
 576                                 $headers[$field] = $v;
 577                         }
 578                 }
 579
 580                 $sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
 581
 582                 // Add fields from the signature block to the header. See issue 8845
 583                 if (!empty($sig_block['created']) && empty($headers['(created)'])) {
 584                         $headers['(created)'] = $sig_block['created'];
 585                 }
 586
 587                 if (!empty($sig_block['expires']) && empty($headers['(expires)'])) {
 588                         $headers['(expires)'] = $sig_block['expires'];
 589                 }
 590
 591                 if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
 592                         Logger::info('No headers or keyId');
 593                         return false;
 594                 }
 595
 596                 $signed_data = '';
 597                 foreach ($sig_block['headers'] as $h) {
 598                         if (array_key_exists($h, $headers)) {
 599                                 $signed_data .= $h . ': ' . $headers[$h] . "\n";
 600                         } else {
 601                                 Logger::info('Requested header field not found', ['field' => $h, 'header' => $headers]);
 602                         }
 603                 }
 604                 $signed_data = rtrim($signed_data, "\n");
 605
 606                 if (empty($signed_data)) {
 607                         Logger::info('Signed data is empty');
 608                         return false;
 609                 }
 610
 611                 $algorithm = null;
 612
 613                 // Wildcard value where signing algorithm should be derived from keyId
 614                 // @see https://tools.ietf.org/html/draft-ietf-httpbis-message-signatures-00#section-4.1
 615                 // Defaulting to SHA256 as it seems to be the prevalent implementation
 616                 // @see https://arewehs2019yet.vpzom.click
 617                 if ($sig_block['algorithm'] === 'hs2019') {
 618                         $algorithm = 'sha256';
 619                 }
 620
 621                 if ($sig_block['algorithm'] === 'rsa-sha256') {
 622                         $algorithm = 'sha256';
 623                 }
 624
 625                 if ($sig_block['algorithm'] === 'rsa-sha512') {
 626                         $algorithm = 'sha512';
 627                 }
 628
 629                 if (empty($algorithm)) {
 630                         Logger::info('No algorithm');
 631                         return false;
 632                 }
 633
 634                 $key = self::fetchKey($sig_block['keyId'], $actor);
 635                 if (empty($key)) {
 636                         Logger::info('Empty key');
 637                         return false;
 638                 }
 639
 640                 if (!empty($key['url']) && !empty($key['type']) && ($key['type'] == 'Tombstone')) {
 641                         Logger::info('Actor is a tombstone', ['key' => $key]);
 642
 643                         if (!Contact::isLocal($key['url'])) {
 644                                 // We now delete everything that we possibly knew from this actor
 645                                 Contact::deleteContactByUrl($key['url']);
 646                         }
 647                         return null;
 648                 }
 649
 650                 if (empty($key['pubkey'])) {
 651                         Logger::info('Empty pubkey');
 652                         return false;
 653                 }
 654
 655                 if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key['pubkey'], $algorithm)) {
 656                         Logger::info('Verification failed', ['signed_data' => $signed_data, 'algorithm' => $algorithm, 'header' => $sig_block['headers'], 'http_headers' => $http_headers]);
 657                         return false;
 658                 }
 659
 660                 $hasGoodSignedContent = false;
 661
 662                 // Check the digest when it is part of the signed data
 663                 if (!empty($content) && in_array('digest', $sig_block['headers'])) {
 664                         $digest = explode('=', $headers['digest'], 2);
 665                         if ($digest[0] === 'SHA-256') {
 666                                 $hashalg = 'sha256';
 667                         }
 668                         if ($digest[0] === 'SHA-512') {
 669                                 $hashalg = 'sha512';
 670                         }
 671
 672                         /// @todo add all hashes from the rfc
 673
 674                         if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
 675                                 Logger::info('Digest does not match');
 676                                 return false;
 677                         }
 678
 679                         $hasGoodSignedContent = true;
 680                 }
 681
 682                 if (in_array('date', $sig_block['headers']) && !empty($headers['date'])) {
 683                         $created = strtotime($headers['date']);
 684                 } elseif (in_array('(created)', $sig_block['headers']) && !empty($sig_block['created'])) {
 685                         $created = $sig_block['created'];
 686                 } else {
 687                         $created = 0;
 688                 }
 689
 690                 if (in_array('(expires)', $sig_block['headers']) && !empty($sig_block['expires'])) {
 691                         $expired = min($sig_block['expires'], $created + 300);
 692                 } else {
 693                         $expired = $created + 300;
 694                 }
 695
 696                 //  Check if the signed date field is in an acceptable range
 697                 if (!empty($created)) {
 698                         $current = time();
 699
 700                         // Calculate with a grace period of 60 seconds to avoid slight time differences between the servers
 701                         if (($created - 60) > $current) {
 702                                 Logger::notice('Signature created in the future', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 703                                 return false;
 704                         }
 705
 706                         if ($current > $expired) {
 707                                 Logger::notice('Signature expired', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 708                                 return false;
 709                         }
 710
 711                         Logger::debug('Valid creation date', ['created' => date(DateTimeFormat::MYSQL, $created), 'expired' => date(DateTimeFormat::MYSQL, $expired), 'current' => date(DateTimeFormat::MYSQL, $current)]);
 712                         $hasGoodSignedContent = true;
 713                 }
 714
 715                 // Check the content-length when it is part of the signed data
 716                 if (in_array('content-length', $sig_block['headers'])) {
 717                         if (strlen($content) != $headers['content-length']) {
 718                                 Logger::info('Content length does not match');
 719                                 return false;
 720                         }
 721                 }
 722
 723                 // Ensure that the authentication had been done with some content
 724                 // Without this check someone could authenticate with fakeable data
 725                 if (!$hasGoodSignedContent) {
 726                         Logger::info('No good signed content');
 727                         return false;
 728                 }
 729
 730                 return $key['url'];
 731         }
 732
 733         /**
 734          * fetches a key for a given id and actor
 735          *
 736          * @param string $id
 737          * @param string $actor
 738          *
 739          * @return array with actor url and public key
 740          * @throws \Exception
 741          */
 742         private static function fetchKey(string $id, string $actor): array
 743         {
 744                 $url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
 745
 746                 $profile = APContact::getByURL($url);
 747                 if (!empty($profile)) {
 748                         Logger::info('Taking key from id', ['id' => $id]);
 749                         return ['url' => $url, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 750                 } elseif ($url != $actor) {
 751                         $profile = APContact::getByURL($actor);
 752                         if (!empty($profile)) {
 753                                 Logger::info('Taking key from actor', ['actor' => $actor]);
 754                                 return ['url' => $actor, 'pubkey' => $profile['pubkey'], 'type' => $profile['type']];
 755                         }
 756                 }
 757
 758                 Logger::notice('Key could not be fetched', ['url' => $url, 'actor' => $actor]);
 759                 return [];
 760         }
 761 }