408 lines
9.7 KiB
PHP
408 lines
9.7 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\Core\Config;
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use Friendica\Database\DBA;
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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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* @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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/**
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* @brief RFC5843
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*
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* Disabled until Friendica's ActivityPub implementation
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* is ready.
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*
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* @see https://tools.ietf.org/html/rfc5843
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*
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* @param string $body The value to create the digest for
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* @param boolean $set (optional, default true)
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* If set send a Digest HTTP header
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*
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* @return string The generated digest of $body
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*/
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// public static function generateDigest($body, $set = true)
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// {
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// $digest = base64_encode(hash('sha256', $body, true));
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//
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// if($set) {
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// header('Digest: SHA-256=' . $digest);
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// }
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// return $digest;
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// }
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// See draft-cavage-http-signatures-08
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public static function verify($data, $key = '')
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{
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$body = $data;
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$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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'content_signed' => false,
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'content_valid' => false
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];
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// Decide if $data arrived via controller submission or curl.
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if (is_array($data) && $data['header']) {
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if (!$data['success']) {
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return $result;
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}
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$h = new HTTPHeaders($data['header']);
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$headers = $h->fetch();
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$body = $data['body'];
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} else {
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$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] = $v;
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}
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}
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}
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$sig_block = null;
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if (array_key_exists('signature', $headers)) {
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$sig_block = self::parseSigheader($headers['signature']);
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} elseif (array_key_exists('authorization', $headers)) {
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$sig_block = self::parseSigheader($headers['authorization']);
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}
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if (!$sig_block) {
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logger('no signature provided.');
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return $result;
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}
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// Warning: This log statement includes binary data
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// logger('sig_block: ' . print_r($sig_block,true), LOGGER_DATA);
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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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$algorithm = null;
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if ($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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$algorithm = 'sha512';
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}
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if ($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('Got keyID ' . $sig_block['keyId']);
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// We don't use Activity Pub at the moment.
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// if (!$key) {
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// $result['signer'] = $sig_block['keyId'];
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// $key = self::getActivitypubKey($sig_block['keyId']);
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// }
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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('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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if (in_array('digest', $signed_headers)) {
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$result['content_signed'] = true;
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$digest = explode('=', $headers['digest']);
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if ($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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$hashalg = 'sha512';
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}
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// The explode operation will have stripped the '=' padding, so compare against unpadded base64.
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if (rtrim(base64_encode(hash($hashalg, $body, true)), '=') === $digest[1]) {
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$result['content_valid'] = true;
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}
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}
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logger('Content_Valid: ' . $result['content_valid']);
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return $result;
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}
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/**
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* Fetch the public key for Activity Pub contact.
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*
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* @param string|int The identifier (contact addr or contact ID).
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* @return string|boolean The public key or false on failure.
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*/
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private static function getActivitypubKey($id)
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{
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if (strpos($id, 'acct:') === 0) {
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$contact = DBA::selectFirst('contact', ['pubkey'], ['uid' => 0, 'addr' => str_replace('acct:', '', $id)]);
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} else {
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$contact = DBA::selectFirst('contact', ['pubkey'], ['id' => $id, 'network' => 'activitypub']);
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}
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if (DBA::isResult($contact)) {
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return $contact['pubkey'];
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}
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if(function_exists('as_fetch')) {
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$r = as_fetch($id);
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}
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if ($r) {
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$j = json_decode($r, true);
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if (array_key_exists('publicKey', $j) && array_key_exists('publicKeyPem', $j['publicKey'])) {
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if ((array_key_exists('id', $j['publicKey']) && $j['publicKey']['id'] !== $id) && $j['id'] !== $id) {
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return false;
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}
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return $j['publicKey']['publicKeyPem'];
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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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* @brief
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*
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* @param string $request
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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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* @param boolean $send_headers (optional, default false)
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* If set send a HTTP header
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* @param boolean $auth (optional, default false)
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* @param string $alg (optional, default 'sha256')
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* @param string $crypt_key (optional, default null)
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* @param string $crypt_algo (optional, default 'aes256ctr')
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*
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* @return array
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*/
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public static function createSig($request, $head, $prvkey, $keyid = 'Key', $send_headers = false, $auth = false, $alg = 'sha256', $crypt_key = null, $crypt_algo = 'aes256ctr')
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{
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$return_headers = [];
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if ($alg === 'sha256') {
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$algorithm = 'rsa-sha256';
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}
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if ($alg === 'sha512') {
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$algorithm = 'rsa-sha512';
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}
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$x = self::sign($request, $head, $prvkey, $alg);
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$headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
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. '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
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if ($crypt_key) {
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$x = Crypto::encapsulate($headerval, $crypt_key, $crypt_algo);
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$headerval = 'iv="' . $x['iv'] . '",key="' . $x['key'] . '",alg="' . $x['alg'] . '",data="' . $x['data'] . '"';
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}
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if ($auth) {
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$sighead = 'Authorization: Signature ' . $headerval;
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} else {
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$sighead = 'Signature: ' . $headerval;
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}
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if ($head) {
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foreach ($head as $k => $v) {
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if ($send_headers) {
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// This is for ActivityPub implementation.
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// Since the Activity Pub implementation isn't
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// ready at the moment, we comment it out.
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// header($k . ': ' . $v);
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} else {
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$return_headers[] = $k . ': ' . $v;
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}
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}
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}
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if ($send_headers) {
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// This is for ActivityPub implementation.
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// Since the Activity Pub implementation isn't
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// ready at the moment, we comment it out.
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// header($sighead);
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} else {
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$return_headers[] = $sighead;
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}
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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 string $request
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* @param array $head
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* @param string $prvkey
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* @param string $alg (optional) default 'sha256'
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*
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* @return array
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*/
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private static function sign($request, $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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if ($request) {
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$headers = '(request-target)' . ': ' . trim($request) . "\n";
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$fields = '(request-target)';
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}
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if ($head) {
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foreach ($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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}
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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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