<?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 $digest; } // See draft-cavage-http-signatures-08 static function verify($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; $h = new \Zotlabs\Web\HTTPHeaders($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)) { $sig_block = self::parse_sigheader($headers['signature']); } elseif(array_key_exists('authorization',$headers)) { $sig_block = self::parse_sigheader($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)) { $result['signer'] = $sig_block['keyId']; $key = $key($sig_block['keyId']); } if(! $key) { $result['signer'] = $sig_block['keyId']; $key = self::get_activitypub_key($sig_block['keyId']); } if(! $key) return $result; $x = rsa_verify($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 $result; } function get_activitypub_key($id) { if(strpos($id,'acct:') === 0) { $x = q("select xchan_pubkey from xchan left join hubloc on xchan_hash = hubloc_hash where hubloc_addr = '%s' limit 1", dbesc(str_replace('acct:','',$id)) ); } else { $x = q("select xchan_pubkey from xchan where xchan_hash = '%s' and xchan_network = 'activitypub' ", dbesc($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',$send_headers = false,$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_alg); $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 $return_headers; } static function sign($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 = []; $matches = []; // if the header is encrypted, decrypt with (default) site private key and continue if(preg_match('/iv="(.*?)"/ism',$header,$matches)) $header = self::decrypt_sigheader($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 $ret; } static function decrypt_sigheader($header,$prvkey = null) { $iv = $key = $alg = $data = null; if(! $prvkey) { $prvkey = get_config('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 ''; } }