+<?php
+
+/**
+ * @file src/Util/HTTPSig.php
+ */
+namespace Friendica\Util;
+
+use Friendica\Core\Config;
+use Friendica\Util\Crypto;
+use Friendica\Util\HTTPHeaders;
+
+/**
+ * @brief Implements HTTP Signatures per draft-cavage-http-signatures-07.
+ *
+ * @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
+ */
+
+class HTTPSig
+{
+ /**
+ * @brief RFC5843
+ *
+ * @see https://tools.ietf.org/html/rfc5843
+ *
+ * @param string $body The value to create the digest for
+ * @param boolean $set (optional, default true)
+ * If set send a Digest HTTP header
+ * @return string The generated digest of $body
+ */
+ public static function generateDigest($body, $set = true)
+ {
+ $digest = base64_encode(hash('sha256', $body, true));
+
+ if($set) {
+ header('Digest: SHA-256=' . $digest);
+ }
+ return $digest;
+ }
+
+ // See draft-cavage-http-signatures-08
+ public static function verify($data, $key = '')
+ {
+ $body = $data;
+ $headers = null;
+ $spoofable = false;
+ $result = [
+ 'signer' => '',
+ 'header_signed' => false,
+ 'header_valid' => false,
+ 'content_signed' => false,
+ 'content_valid' => false
+ ];
+
+ // Decide if $data arrived via controller submission or curl.
+ if (is_array($data) && $data['header']) {
+ if (!$data['success']) {
+ return $result;
+ }
+
+ $h = new HTTPHeaders($data['header']);
+ $headers = $h->fetcharr();
+ $body = $data['body'];
+ } else {
+ $headers = [];
+ $headers['(request-target)'] = strtolower($_SERVER['REQUEST_METHOD']).' '.$_SERVER['REQUEST_URI'];
+
+ foreach ($_SERVER as $k => $v) {
+ if (strpos($k, 'HTTP_') === 0) {
+ $field = str_replace('_', '-', strtolower(substr($k, 5)));
+ $headers[$field] = $v;
+ }
+ }
+ }
+
+ $sig_block = null;
+
+ if (array_key_exists('signature', $headers)) {
+ $sig_block = self::parseSigheader($headers['signature']);
+ } elseif (array_key_exists('authorization', $headers)) {
+ $sig_block = self::parseSigheader($headers['authorization']);
+ }
+
+ if (!$sig_block) {
+ logger('no signature provided.');
+ return $result;
+ }
+
+ // Warning: This log statement includes binary data
+ // logger('sig_block: ' . print_r($sig_block,true), LOGGER_DATA);
+
+ $result['header_signed'] = true;
+
+ $signed_headers = $sig_block['headers'];
+ if (!$signed_headers) {
+ $signed_headers = ['date'];
+ }
+
+ $signed_data = '';
+ foreach ($signed_headers as $h) {
+ if (array_key_exists($h, $headers)) {
+ $signed_data .= $h . ': ' . $headers[$h] . "\n";
+ }
+ if (strpos($h, '.')) {
+ $spoofable = true;
+ }
+ }
+
+ $signed_data = rtrim($signed_data, "\n");
+
+ $algorithm = null;
+ if ($sig_block['algorithm'] === 'rsa-sha256') {
+ $algorithm = 'sha256';
+ }
+ if ($sig_block['algorithm'] === 'rsa-sha512') {
+ $algorithm = 'sha512';
+ }
+
+ if ($key && function_exists($key)) { /// @todo What function do we check for - maybe we check now for a method !!!
+ $result['signer'] = $sig_block['keyId'];
+ $key = $key($sig_block['keyId']);
+ }
+
+ if (!$key) {
+ return $result;
+ }
+
+ $x = Crypto::rsaVerify($signed_data, $sig_block['signature'], $key, $algorithm);
+
+ logger('verified: ' . $x, LOGGER_DEBUG);
+
+ if (!$x) {
+ return $result;
+ }
+
+ if (!$spoofable) {
+ $result['header_valid'] = true;
+ }
+
+ if (in_array('digest', $signed_headers)) {
+ $result['content_signed'] = true;
+ $digest = explode('=', $headers['digest']);
+
+ if ($digest[0] === 'SHA-256') {
+ $hashalg = 'sha256';
+ }
+ if ($digest[0] === 'SHA-512') {
+ $hashalg = 'sha512';
+ }
+
+ // The explode operation will have stripped the '=' padding, so compare against unpadded base64.
+ if (rtrim(base64_encode(hash($hashalg, $body, true)), '=') === $digest[1]) {
+ $result['content_valid'] = true;
+ }
+ }
+
+ logger('Content_Valid: ' . $result['content_valid']);
+
+ return $result;
+ }
+
+ /**
+ * @brief
+ *
+ * @param string $request
+ * @param array $head
+ * @param string $prvkey
+ * @param string $keyid (optional, default 'Key')
+ * @param boolean $send_headers (optional, default false)
+ * If set send a HTTP header
+ * @param boolean $auth (optional, default false)
+ * @param string $alg (optional, default 'sha256')
+ * @param string $crypt_key (optional, default null)
+ * @param string $crypt_algo (optional, default 'aes256ctr')
+ *
+ * @return array
+ */
+ public static function createSig($request, $head, $prvkey, $keyid = 'Key', $send_headers = false, $auth = false, $alg = 'sha256', $crypt_key = null, $crypt_algo = 'aes256ctr')
+ {
+ $return_headers = [];
+
+ if ($alg === 'sha256') {
+ $algorithm = 'rsa-sha256';
+ }
+
+ if ($alg === 'sha512') {
+ $algorithm = 'rsa-sha512';
+ }
+
+ $x = self::sign($request, $head, $prvkey, $alg);
+
+ $headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm
+ . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
+
+ if ($crypt_key) {
+ $x = Crypto::encapsulate($headerval, $crypt_key, $crypt_algo);
+ $headerval = 'iv="' . $x['iv'] . '",key="' . $x['key'] . '",alg="' . $x['alg'] . '",data="' . $x['data'] . '"';
+ }
+
+ if ($auth) {
+ $sighead = 'Authorization: Signature ' . $headerval;
+ } else {
+ $sighead = 'Signature: ' . $headerval;
+ }
+
+ if ($head) {
+ foreach ($head as $k => $v) {
+ if ($send_headers) {
+ header($k . ': ' . $v);
+ } else {
+ $return_headers[] = $k . ': ' . $v;
+ }
+ }
+ }
+
+ if ($send_headers) {
+ header($sighead);
+ } else {
+ $return_headers[] = $sighead;
+ }
+
+ return $return_headers;
+ }
+
+ /**
+ * @brief
+ *
+ * @param string $request
+ * @param array $head
+ * @param string $prvkey
+ * @param string $alg (optional) default 'sha256'
+ *
+ * @return array
+ */
+ private static function sign($request, $head, $prvkey, $alg = 'sha256')
+ {
+ $ret = [];
+ $headers = '';
+ $fields = '';
+
+ if ($request) {
+ $headers = '(request-target)' . ': ' . trim($request) . "\n";
+ $fields = '(request-target)';
+ }
+
+ if ($head) {
+ foreach ($head as $k => $v) {
+ $headers .= strtolower($k) . ': ' . trim($v) . "\n";
+ if ($fields) {
+ $fields .= ' ';
+ }
+ $fields .= strtolower($k);
+ }
+ // strip the trailing linefeed
+ $headers = rtrim($headers, "\n");
+ }
+
+ $sig = base64_encode(Crypto::rsaSign($headers, $prvkey, $alg));
+
+ $ret['headers'] = $fields;
+ $ret['signature'] = $sig;
+
+ return $ret;
+ }
+
+ /**
+ * @brief
+ *
+ * @param string $header
+ * @return array associate array with
+ * - \e string \b keyID
+ * - \e string \b algorithm
+ * - \e array \b headers
+ * - \e string \b signature
+ */
+ public static function parseSigheader($header)
+ {
+ $ret = [];
+ $matches = [];
+
+ // if the header is encrypted, decrypt with (default) site private key and continue
+ if (preg_match('/iv="(.*?)"/ism', $header, $matches)) {
+ $header = self::decryptSigheader($header);
+ }
+
+ if (preg_match('/keyId="(.*?)"/ism', $header, $matches)) {
+ $ret['keyId'] = $matches[1];
+ }
+
+ if (preg_match('/algorithm="(.*?)"/ism', $header, $matches)) {
+ $ret['algorithm'] = $matches[1];
+ }
+
+ if (preg_match('/headers="(.*?)"/ism', $header, $matches)) {
+ $ret['headers'] = explode(' ', $matches[1]);
+ }
+
+ if (preg_match('/signature="(.*?)"/ism', $header, $matches)) {
+ $ret['signature'] = base64_decode(preg_replace('/\s+/', '', $matches[1]));
+ }
+
+ if (($ret['signature']) && ($ret['algorithm']) && (!$ret['headers'])) {
+ $ret['headers'] = ['date'];
+ }
+
+ return $ret;
+ }
+
+ /**
+ * @brief
+ *
+ * @param string $header
+ * @param string $prvkey (optional), if not set use site private key
+ *
+ * @return array|string associative array, empty string if failue
+ * - \e string \b iv
+ * - \e string \b key
+ * - \e string \b alg
+ * - \e string \b data
+ */
+ private static function decryptSigheader($header, $prvkey = null)
+ {
+ $iv = $key = $alg = $data = null;
+
+ if (!$prvkey) {
+ $prvkey = Config::get('system', 'prvkey');
+ }
+
+ $matches = [];
+
+ if (preg_match('/iv="(.*?)"/ism', $header, $matches)) {
+ $iv = $matches[1];
+ }
+
+ if (preg_match('/key="(.*?)"/ism', $header, $matches)) {
+ $key = $matches[1];
+ }
+
+ if (preg_match('/alg="(.*?)"/ism', $header, $matches)) {
+ $alg = $matches[1];
+ }
+
+ if (preg_match('/data="(.*?)"/ism', $header, $matches)) {
+ $data = $matches[1];
+ }
+
+ if ($iv && $key && $alg && $data) {
+ return Crypto::unencapsulate(['iv' => $iv, 'key' => $key, 'alg' => $alg, 'data' => $data], $prvkey);
+ }
+
+ return '';
+ }
+}