496 lines
12 KiB
PHP
496 lines
12 KiB
PHP
<?php
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/**
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* @file src/Util/HTTPSignature.php
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*/
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namespace Friendica\Util;
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use Friendica\BaseObject;
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use Friendica\Core\Config;
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use Friendica\Core\Logger;
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use Friendica\Database\DBA;
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use Friendica\Model\User;
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use Friendica\Model\APContact;
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use Friendica\Protocol\ActivityPub;
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/**
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* @brief Implements HTTP Signatures per draft-cavage-http-signatures-07.
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*
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* Ported from Hubzilla: https://framagit.org/hubzilla/core/blob/master/Zotlabs/Web/HTTPSig.php
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*
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* Other parts of the code for HTTP signing are taken from the Osada project.
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* https://framagit.org/macgirvin/osada
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*
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* @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
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*/
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class HTTPSignature
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{
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// See draft-cavage-http-signatures-08
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/**
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* @brief Verifies a magic request
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*
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* @param $key
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*
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* @return array with verification data
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*/
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public static function verifyMagic($key)
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{
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$headers = null;
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$spoofable = false;
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$result = [
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'signer' => '',
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'header_signed' => false,
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'header_valid' => false
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];
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// Decide if $data arrived via controller submission or curl.
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$headers = [];
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$headers['(request-target)'] = strtolower($_SERVER['REQUEST_METHOD']).' '.$_SERVER['REQUEST_URI'];
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foreach ($_SERVER as $k => $v) {
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if (strpos($k, 'HTTP_') === 0) {
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$field = str_replace('_', '-', strtolower(substr($k, 5)));
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$headers[$field] = $v;
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}
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}
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$sig_block = null;
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$sig_block = self::parseSigheader($headers['authorization']);
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if (!$sig_block) {
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Logger::log('no signature provided.');
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return $result;
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}
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$result['header_signed'] = true;
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$signed_headers = $sig_block['headers'];
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if (!$signed_headers) {
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$signed_headers = ['date'];
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}
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$signed_data = '';
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foreach ($signed_headers as $h) {
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if (array_key_exists($h, $headers)) {
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$signed_data .= $h . ': ' . $headers[$h] . "\n";
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}
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if (strpos($h, '.')) {
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$spoofable = true;
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}
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}
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$signed_data = rtrim($signed_data, "\n");
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$algorithm = 'sha512';
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if ($key && function_exists($key)) {
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$result['signer'] = $sig_block['keyId'];
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$key = $key($sig_block['keyId']);
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}
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Logger::log('Got keyID ' . $sig_block['keyId'], Logger::DEBUG);
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if (!$key) {
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return $result;
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}
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$x = Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm);
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Logger::log('verified: ' . $x, Logger::DEBUG);
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if (!$x) {
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return $result;
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}
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if (!$spoofable) {
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$result['header_valid'] = true;
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}
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return $result;
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}
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/**
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* @brief
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*
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* @param array $head
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* @param string $prvkey
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* @param string $keyid (optional, default 'Key')
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*
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* @return array
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*/
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public static function createSig($head, $prvkey, $keyid = 'Key')
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{
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$return_headers = [];
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$alg = 'sha512';
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$algorithm = 'rsa-sha512';
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$x = self::sign($head, $prvkey, $alg);
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$headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
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. '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
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$sighead = 'Authorization: Signature ' . $headerval;
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if ($head) {
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foreach ($head as $k => $v) {
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$return_headers[] = $k . ': ' . $v;
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}
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}
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$return_headers[] = $sighead;
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return $return_headers;
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}
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/**
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* @brief
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*
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* @param array $head
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* @param string $prvkey
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* @param string $alg (optional) default 'sha256'
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*
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* @return array
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*/
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private static function sign($head, $prvkey, $alg = 'sha256')
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{
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$ret = [];
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$headers = '';
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$fields = '';
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foreach ($head as $k => $v) {
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$headers .= strtolower($k) . ': ' . trim($v) . "\n";
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if ($fields) {
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$fields .= ' ';
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}
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$fields .= strtolower($k);
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}
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// strip the trailing linefeed
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$headers = rtrim($headers, "\n");
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$sig = base64_encode(Crypto::rsaSign($headers, $prvkey, $alg));
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$ret['headers'] = $fields;
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$ret['signature'] = $sig;
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return $ret;
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}
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/**
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* @brief
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*
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* @param string $header
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* @return array associate array with
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* - \e string \b keyID
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* - \e string \b algorithm
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* - \e array \b headers
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* - \e string \b signature
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*/
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public static function parseSigheader($header)
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{
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$ret = [];
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$matches = [];
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// if the header is encrypted, decrypt with (default) site private key and continue
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if (preg_match('/iv="(.*?)"/ism', $header, $matches)) {
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$header = self::decryptSigheader($header);
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}
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if (preg_match('/keyId="(.*?)"/ism', $header, $matches)) {
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$ret['keyId'] = $matches[1];
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}
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if (preg_match('/algorithm="(.*?)"/ism', $header, $matches)) {
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$ret['algorithm'] = $matches[1];
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}
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if (preg_match('/headers="(.*?)"/ism', $header, $matches)) {
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$ret['headers'] = explode(' ', $matches[1]);
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}
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if (preg_match('/signature="(.*?)"/ism', $header, $matches)) {
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$ret['signature'] = base64_decode(preg_replace('/\s+/', '', $matches[1]));
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}
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if (($ret['signature']) && ($ret['algorithm']) && (!$ret['headers'])) {
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$ret['headers'] = ['date'];
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}
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return $ret;
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}
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/**
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* @brief
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*
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* @param string $header
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* @param string $prvkey (optional), if not set use site private key
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*
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* @return array|string associative array, empty string if failue
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* - \e string \b iv
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* - \e string \b key
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* - \e string \b alg
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* - \e string \b data
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*/
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private static function decryptSigheader($header, $prvkey = null)
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{
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$iv = $key = $alg = $data = null;
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if (!$prvkey) {
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$prvkey = Config::get('system', 'prvkey');
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}
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$matches = [];
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if (preg_match('/iv="(.*?)"/ism', $header, $matches)) {
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$iv = $matches[1];
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}
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if (preg_match('/key="(.*?)"/ism', $header, $matches)) {
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$key = $matches[1];
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}
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if (preg_match('/alg="(.*?)"/ism', $header, $matches)) {
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$alg = $matches[1];
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}
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if (preg_match('/data="(.*?)"/ism', $header, $matches)) {
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$data = $matches[1];
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}
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if ($iv && $key && $alg && $data) {
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return Crypto::unencapsulate(['iv' => $iv, 'key' => $key, 'alg' => $alg, 'data' => $data], $prvkey);
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}
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return '';
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}
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/*
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* Functions for ActivityPub
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*/
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/**
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* @brief Transmit given data to a target for a user
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*
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* @param array $data Data that is about to be send
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* @param string $target The URL of the inbox
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* @param integer $uid User id of the sender
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*
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* @return boolean Was the transmission successful?
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*/
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public static function transmit($data, $target, $uid)
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{
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$owner = User::getOwnerDataById($uid);
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if (!$owner) {
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return;
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}
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$content = json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
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// Header data that is about to be signed.
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$host = parse_url($target, PHP_URL_HOST);
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$path = parse_url($target, PHP_URL_PATH);
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$digest = 'SHA-256=' . base64_encode(hash('sha256', $content, true));
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$content_length = strlen($content);
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$headers = ['Content-Length: ' . $content_length, 'Digest: ' . $digest, 'Host: ' . $host];
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$signed_data = "(request-target): post " . $path . "\ncontent-length: " . $content_length . "\ndigest: " . $digest . "\nhost: " . $host;
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$signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
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$headers[] = 'Signature: keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) content-length digest host",signature="' . $signature . '"';
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$headers[] = 'Content-Type: application/activity+json';
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$postResult = Network::post($target, $content, $headers);
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$return_code = $postResult->getReturnCode();
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Logger::log('Transmit to ' . $target . ' returned ' . $return_code, Logger::DEBUG);
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return ($return_code >= 200) && ($return_code <= 299);
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}
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/**
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* @brief Fetches JSON data for a user
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*
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* @param string $request request url
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* @param integer $uid User id of the requester
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*
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* @return array JSON array
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*/
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public static function fetch($request, $uid)
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{
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$owner = User::getOwnerDataById($uid);
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if (!$owner) {
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return;
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}
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// Header data that is about to be signed.
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$host = parse_url($request, PHP_URL_HOST);
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$path = parse_url($request, PHP_URL_PATH);
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$headers = ['Host: ' . $host];
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$signed_data = "(request-target): get " . $path . "\nhost: " . $host;
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$signature = base64_encode(Crypto::rsaSign($signed_data, $owner['uprvkey'], 'sha256'));
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$headers[] = 'Signature: keyId="' . $owner['url'] . '#main-key' . '",algorithm="rsa-sha256",headers="(request-target) host",signature="' . $signature . '"';
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$headers[] = 'Accept: application/activity+json, application/ld+json';
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$curlResult = Network::curl($request, false, $redirects, ['header' => $headers]);
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$return_code = $curlResult->getReturnCode();
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Logger::log('Fetched for user ' . $uid . ' from ' . $request . ' returned ' . $return_code, Logger::DEBUG);
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if (!$curlResult->isSuccess() || empty($curlResult->getBody())) {
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return false;
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}
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$content = json_decode($curlResult->getBody(), true);
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if (empty($content) || !is_array($content)) {
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return false;
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}
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return $content;
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}
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/**
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* @brief Gets a signer from a given HTTP request
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*
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* @param $content
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* @param $http_headers
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*
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* @return signer string
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*/
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public static function getSigner($content, $http_headers)
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{
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$object = json_decode($content, true);
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if (empty($object)) {
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return false;
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}
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$actor = JsonLD::fetchElement($object, 'actor', 'id');
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$headers = [];
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$headers['(request-target)'] = strtolower($http_headers['REQUEST_METHOD']) . ' ' . $http_headers['REQUEST_URI'];
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// First take every header
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foreach ($http_headers as $k => $v) {
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$field = str_replace('_', '-', strtolower($k));
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$headers[$field] = $v;
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}
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// Now add every http header
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foreach ($http_headers as $k => $v) {
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if (strpos($k, 'HTTP_') === 0) {
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$field = str_replace('_', '-', strtolower(substr($k, 5)));
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$headers[$field] = $v;
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}
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}
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$sig_block = self::parseSigHeader($http_headers['HTTP_SIGNATURE']);
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if (empty($sig_block) || empty($sig_block['headers']) || empty($sig_block['keyId'])) {
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return false;
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}
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$signed_data = '';
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foreach ($sig_block['headers'] as $h) {
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if (array_key_exists($h, $headers)) {
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$signed_data .= $h . ': ' . $headers[$h] . "\n";
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}
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}
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$signed_data = rtrim($signed_data, "\n");
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if (empty($signed_data)) {
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return false;
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}
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$algorithm = null;
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if ($sig_block['algorithm'] === 'rsa-sha256') {
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$algorithm = 'sha256';
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}
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if ($sig_block['algorithm'] === 'rsa-sha512') {
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$algorithm = 'sha512';
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}
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if (empty($algorithm)) {
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return false;
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}
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$key = self::fetchKey($sig_block['keyId'], $actor);
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if (empty($key)) {
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return false;
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}
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if (!Crypto::rsaVerify($signed_data, $sig_block['signature'], $key['pubkey'], $algorithm)) {
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return false;
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}
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// Check the digest when it is part of the signed data
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if (in_array('digest', $sig_block['headers'])) {
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$digest = explode('=', $headers['digest'], 2);
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if ($digest[0] === 'SHA-256') {
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$hashalg = 'sha256';
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}
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if ($digest[0] === 'SHA-512') {
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$hashalg = 'sha512';
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}
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/// @todo add all hashes from the rfc
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if (!empty($hashalg) && base64_encode(hash($hashalg, $content, true)) != $digest[1]) {
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return false;
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}
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}
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/// @todo Check if the signed date field is in an acceptable range
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// Check the content-length when it is part of the signed data
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if (in_array('content-length', $sig_block['headers'])) {
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if (strlen($content) != $headers['content-length']) {
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return false;
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}
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}
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return $key['url'];
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}
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/**
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* @brief fetches a key for a given id and actor
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*
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* @param $id
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* @param $actor
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*
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* @return array with actor url and public key
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*/
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private static function fetchKey($id, $actor)
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{
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$url = (strpos($id, '#') ? substr($id, 0, strpos($id, '#')) : $id);
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$profile = APContact::getByURL($url);
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if (!empty($profile)) {
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Logger::log('Taking key from id ' . $id, Logger::DEBUG);
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return ['url' => $url, 'pubkey' => $profile['pubkey']];
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} elseif ($url != $actor) {
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$profile = APContact::getByURL($actor);
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if (!empty($profile)) {
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Logger::log('Taking key from actor ' . $actor, Logger::DEBUG);
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return ['url' => $actor, 'pubkey' => $profile['pubkey']];
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}
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}
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return false;
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}
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}
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