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-rw-r--r--Zotlabs/Web/HTTPSig.php220
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+<?php
+
+namespace Zotlabs\Web;
+
+/**
+ * Implements HTTP Signatures per draft-cavage-http-signatures-07
+ */
+
+
+class HTTPSig {
+
+ // See RFC5843
+
+ static function generate_digest($body,$set = true) {
+ $digest = base64_encode(hash('sha256',$body,true));
+
+ if($set) {
+ header('Digest: SHA-256=' . $digest);
+ }
+ return $digest;
+ }
+
+ // See draft-cavage-http-signatures-07
+
+ static function verify($data,$key = '') {
+
+ $body = $data;
+ $headers = null;
+
+ // decide if $data arrived via controller submission or curl
+ if(is_array($data) && $data['header']) {
+ if(! $data['success'])
+ return false;
+ $h = new \Zotlabs\Web\HTTPHeaders($data['header']);
+ $headers = $h->fetcharr();
+ $body = $data['body'];
+ }
+
+ else {
+ $headers = [];
+ $headers['(request-target)'] =
+ $_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)) {
+ $sig_block = self::parse_sigheader($headers['signature']);
+ }
+ elseif(array_key_exists('authorization',$headers)) {
+ $sig_block = self::parse_sigheader($headers['authorization']);
+ }
+
+ if(! $sig_block)
+ return null;
+
+ $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";
+ }
+ }
+ $signed_data = rtrim($signed_data,"\n");
+
+ $algorithm = null;
+ if($sig_block['algorithm'] === 'rsa-sha256') {
+ $algorithm = 'sha256';
+ }
+
+ if(! $key) {
+ $key = self::get_activitypub_key($sig_block['keyId']);
+ }
+
+ if(! $key)
+ return null;
+
+ $x = rsa_verify($signed_data,$sig_block['signature'],$key,$algorithm);
+
+ if($x === false)
+ return $x;
+
+ if(in_array('digest',$signed_headers)) {
+ $digest = explode('=', $headers['digest']);
+ if($digest[0] === 'SHA-256')
+ $hashalg = 'sha256';
+
+ // The explode operation will have stripped the '=' padding, so compare against unpadded base64
+ if(rtrim(base64_encode(hash($hashalg,$body,true)),'=') === $digest[1])
+ return true;
+ else
+ return false;
+ }
+
+ return $x;
+
+ }
+
+ function get_activitypub_key($id) {
+
+ $x = q("select xchan_pubkey from xchan where xchan_hash = '%s' and xchan_network = 'activitypub' ",
+ dbesc($id)
+ );
+
+ if($x && $x[0]['xchan_pubkey']) {
+ return ($x[0]['xchan_pubkey']);
+ }
+ $r = as_fetch($id);
+
+ if($r) {
+ $j = json_decode($r,true);
+
+ if($j['id'] !== $id)
+ return false;
+ if(array_key_exists('publicKey',$j) && array_key_exists('publicKeyPem',$j['publicKey'])) {
+ return($j['publicKey']['publicKeyPem']);
+ }
+ }
+ return false;
+ }
+
+
+
+
+ static function create_sig($request,$head,$prvkey,$keyid = 'Key',$send_headers = false,$alg = 'sha256') {
+
+ $return_headers = [];
+
+ if($alg === 'sha256') {
+ $algorithm = 'rsa-sha256';
+ }
+
+ $x = self::sign($request,$head,$prvkey,$alg);
+
+ $sighead = 'Signature: keyId="' . $keyid . '",algorithm="' . $algorithm
+ . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
+
+ if($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 $return_headers;
+ }
+
+
+
+ static function sign($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");
+ }
+
+ $sig = base64_encode(rsa_sign($headers,$prvkey,$alg));
+
+ $ret['headers'] = $fields;
+ $ret['signature'] = $sig;
+
+ return $ret;
+ }
+
+ static function parse_sigheader($header) {
+ $ret = [];
+ $matches = [];
+ if(preg_match('/keyId="(.*?)"/ism',$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;
+ }
+
+
+}
+
+