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<?php
namespace Zotlabs\Web;
use Zotlabs\Lib\ActivityStreams;
use Zotlabs\Lib\Webfinger;
use Zotlabs\Web\HTTPHeaders;
use Zotlabs\Lib\Libzot;
/**
* @brief Implements HTTP Signatures per draft-cavage-http-signatures-10.
*
* @see https://tools.ietf.org/html/draft-cavage-http-signatures-10
*/
class HTTPSig {
/**
* @brief RFC5843
*
* @see https://tools.ietf.org/html/rfc5843
*
* @param string $body The value to create the digest for
* @param string $alg hash algorithm (one of 'sha256','sha512')
* @return string The generated digest header string for $body
*/
static function generate_digest_header($body,$alg = 'sha256') {
$digest = base64_encode(hash($alg, $body, true));
switch($alg) {
case 'sha512':
return 'SHA-512=' . $digest;
case 'sha256':
default:
return 'SHA-256=' . $digest;
break;
}
}
static function find_headers($data,&$body) {
// decide if $data arrived via controller submission or curl
if(is_array($data) && $data['header']) {
if(! $data['success'])
return [];
$h = new HTTPHeaders($data['header']);
$headers = $h->fetcharr();
$body = $data['body'];
$headers['(request-target)'] = $data['request_target'];
}
else {
$headers = [];
$headers['(request-target)'] = strtolower($_SERVER['REQUEST_METHOD']) . ' ' . $_SERVER['REQUEST_URI'];
$headers['content-type'] = $_SERVER['CONTENT_TYPE'];
$headers['content-length'] = $_SERVER['CONTENT_LENGTH'];
foreach($_SERVER as $k => $v) {
if(strpos($k,'HTTP_') === 0) {
$field = str_replace('_','-',strtolower(substr($k,5)));
$headers[$field] = $v;
}
}
}
//logger('SERVER: ' . print_r($_SERVER,true), LOGGER_ALL);
//logger('headers: ' . print_r($headers,true), LOGGER_ALL);
return $headers;
}
// See draft-cavage-http-signatures-10
static function verify($data,$key = '', $keytype = '') {
$body = $data;
$headers = null;
$result = [
'signer' => '',
'portable_id' => '',
'header_signed' => false,
'header_valid' => false,
'content_signed' => false,
'content_valid' => false
];
$headers = self::find_headers($data,$body);
if(! $headers)
return $result;
$sig_block = null;
if(array_key_exists('signature',$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.', LOGGER_DEBUG);
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($h === 'date') {
$d = new \DateTime($headers[$h]);
$d->setTimeZone(new \DateTimeZone('UTC'));
$dplus = datetime_convert('UTC','UTC','now + 1 day');
$dminus = datetime_convert('UTC','UTC','now - 1 day');
$c = $d->format('Y-m-d H:i:s');
if($c > $dplus || $c < $dminus) {
logger('bad time: ' . $c);
return $result;
}
}
}
$signed_data = rtrim($signed_data,"\n");
$algorithm = null;
if($sig_block['algorithm'] === 'rsa-sha256') {
$algorithm = 'sha256';
}
if($sig_block['algorithm'] === 'rsa-sha512') {
$algorithm = 'sha512';
}
if(! array_key_exists('keyId',$sig_block))
return $result;
$result['signer'] = $sig_block['keyId'];
$key = self::get_key($key,$keytype,$result['signer']);
if(! ($key && $key['public_key'])) {
return $result;
}
$x = rsa_verify($signed_data,$sig_block['signature'],$key['public_key'],$algorithm);
logger('verified: ' . $x, LOGGER_DEBUG);
if(! $x) {
// try again, ignoring the local actor (xchan) cache and refetching the key
// from its source
$fkey = self::get_key($key,$keytype,$result['signer'],true);
if ($fkey && $fkey['public_key']) {
$y = rsa_verify($signed_data,$sig_block['signature'],$fkey['public_key'],$algorithm);
logger('verified: (cache reload) ' . $x, LOGGER_DEBUG);
}
if (! $y) {
logger('verify failed for ' . $result['signer'] . ' alg=' . $algorithm . (($fkey['public_key']) ? '' : ' no key'));
$sig_block['signature'] = base64_encode($sig_block['signature']);
logger('affected sigblock: ' . print_r($sig_block,true));
logger('headers: ' . print_r($headers,true));
logger('server: ' . print_r($_SERVER,true));
return $result;
}
}
$result['portable_id'] = $key['portable_id'];
$result['header_valid'] = true;
if(in_array('digest',$signed_headers)) {
$result['content_signed'] = true;
$digest = explode('=', $headers['digest'], 2);
if($digest[0] === 'SHA-256')
$hashalg = 'sha256';
if($digest[0] === 'SHA-512')
$hashalg = 'sha512';
if(base64_encode(hash($hashalg,$body,true)) === $digest[1]) {
$result['content_valid'] = true;
}
logger('Content_Valid: ' . (($result['content_valid']) ? 'true' : 'false'));
if (! $result['content_valid']) {
logger('invalid content signature: data ' . print_r($data,true));
logger('invalid content signature: headers ' . print_r($headers,true));
logger('invalid content signature: body ' . print_r($body,true));
}
}
return $result;
}
static function get_key($key,$keytype,$id) {
if($key) {
if(function_exists($key)) {
return $key($id);
}
return [ 'public_key' => $key ];
}
if($keytype === 'zot6') {
$key = self::get_zotfinger_key($id,$force);
if($key) {
return $key;
}
}
if(strpos($id,'#') === false) {
$key = self::get_webfinger_key($id);
}
if(! $key) {
$key = self::get_activitystreams_key($id);
}
return $key;
}
function convertKey($key) {
if(strstr($key,'RSA ')) {
return rsatopem($key);
}
elseif(substr($key,0,5) === 'data:') {
return convert_salmon_key($key);
}
else {
return $key;
}
}
/**
* @brief
*
* @param string $id
* @return boolean|string
* false if no pub key found, otherwise return the pub key
*/
function get_activitystreams_key($id) {
// remove fragment
$url = ((strpos($id,'#')) ? substr($id,0,strpos($id,'#')) : $id);
$x = q("select * from xchan left join hubloc on xchan_hash = hubloc_hash where hubloc_addr = '%s' or hubloc_id_url = '%s' and hubloc_network in ('zot6', 'activitypub')",
dbesc(str_replace('acct:','',$url)),
dbesc($url)
);
$x = Libzot::zot_record_preferred($x);
if($x && $x['xchan_pubkey']) {
return [ 'portable_id' => $x['xchan_hash'], 'public_key' => $x['xchan_pubkey'] , 'hubloc' => $x ];
}
$r = ActivityStreams::fetch($id);
if($r) {
if(array_key_exists('publicKey',$r) && array_key_exists('publicKeyPem',$r['publicKey']) && array_key_exists('id',$r['publicKey'])) {
if($r['publicKey']['id'] === $id || $r['id'] === $id) {
$portable_id = ((array_key_exists('owner',$r['publicKey'])) ? $r['publicKey']['owner'] : EMPTY_STR);
return [ 'public_key' => self::convertKey($r['publicKey']['publicKeyPem']), 'portable_id' => $portable_id, 'hubloc' => [] ];
}
}
}
return false;
}
function get_webfinger_key($id) {
$x = q("select * from xchan left join hubloc on xchan_hash = hubloc_hash where hubloc_addr = '%s' or hubloc_id_url = '%s'",
dbesc(str_replace('acct:','',$id)),
dbesc($id)
);
$x = Libzot::zot_record_preferred($x);
if($x && $x['xchan_pubkey']) {
return [ 'portable_id' => $x['xchan_hash'], 'public_key' => $x['xchan_pubkey'] , 'hubloc' => $x ];
}
$wf = Webfinger::exec($id);
$key = [ 'portable_id' => '', 'public_key' => '', 'hubloc' => [] ];
if($wf) {
if(array_key_exists('properties',$wf) && array_key_exists('https://w3id.org/security/v1#publicKeyPem',$wf['properties'])) {
$key['public_key'] = self::convertKey($wf['properties']['https://w3id.org/security/v1#publicKeyPem']);
}
if(array_key_exists('links', $wf) && is_array($wf['links'])) {
foreach($wf['links'] as $l) {
if(! (is_array($l) && array_key_exists('rel',$l))) {
continue;
}
if($l['rel'] === 'magic-public-key' && array_key_exists('href',$l) && $key['public_key'] === EMPTY_STR) {
$key['public_key'] = self::convertKey($l['href']);
}
}
}
}
return (($key['public_key']) ? $key : false);
}
function get_zotfinger_key($id) {
$x = q("select * from xchan left join hubloc on xchan_hash = hubloc_hash where hubloc_addr = '%s' or hubloc_id_url = '%s' and hubloc_network = 'zot6'",
dbesc(str_replace('acct:','',$id)),
dbesc($id)
);
if($x && $x[0]['xchan_pubkey']) {
return [ 'portable_id' => $x[0]['xchan_hash'], 'public_key' => $x[0]['xchan_pubkey'] , 'hubloc' => $x[0] ];
}
$wf = Webfinger::exec($id);
$key = [ 'portable_id' => '', 'public_key' => '', 'hubloc' => [] ];
if($wf) {
if(array_key_exists('properties',$wf) && array_key_exists('https://w3id.org/security/v1#publicKeyPem',$wf['properties'])) {
$key['public_key'] = self::convertKey($wf['properties']['https://w3id.org/security/v1#publicKeyPem']);
}
if(array_key_exists('links', $wf) && is_array($wf['links'])) {
foreach($wf['links'] as $l) {
if(! (is_array($l) && array_key_exists('rel',$l))) {
continue;
}
if($l['rel'] === 'http://purl.org/zot/protocol/6.0' && array_key_exists('href',$l) && $l['href'] !== EMPTY_STR) {
// The third argument to Zotfinger::exec() tells it not to verify signatures
// Since we're inside a function that is fetching keys with which to verify signatures,
// this is necessary to prevent infinite loops.
$z = \Zotlabs\Lib\Zotfinger::exec($l['href'],null,false);
if($z) {
$i = Libzot::import_xchan($z['data']);
if($i['success']) {
$key['portable_id'] = $i['hash'];
$x = q("select * from xchan left join hubloc on xchan_hash = hubloc_hash where hubloc_id_url = '%s' and hubloc_network = 'zot6'",
dbesc($l['href'])
);
if($x) {
$key['hubloc'] = $x[0];
}
}
}
}
if($l['rel'] === 'magic-public-key' && array_key_exists('href',$l) && $key['public_key'] === EMPTY_STR) {
$key['public_key'] = self::convertKey($l['href']);
}
}
}
}
return (($key['public_key']) ? $key : false);
}
/**
* @brief
*
* @param array $head
* @param string $prvkey
* @param string $keyid (optional, default '')
* @param boolean $auth (optional, default false)
* @param string $alg (optional, default 'sha256')
* @param array $encryption [ 'key', 'algorithm' ] or false
* @return array
*/
static function create_sig($head, $prvkey, $keyid = EMPTY_STR, $auth = false, $alg = 'sha256', $encryption = false ) {
$return_headers = [];
if($alg === 'sha256') {
$algorithm = 'rsa-sha256';
}
if($alg === 'sha512') {
$algorithm = 'rsa-sha512';
}
$x = self::sign($head,$prvkey,$alg);
$headerval = 'keyId="' . $keyid . '",algorithm="' . $algorithm . '",headers="' . $x['headers'] . '",signature="' . $x['signature'] . '"';
if($encryption) {
$x = crypto_encapsulate($headerval,$encryption['key'],$encryption['algorithm']);
if(is_array($x)) {
$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 => $v) {
// strip the request-target virtual header from the output headers
if($k === '(request-target)') {
continue;
}
$return_headers[] = $k . ': ' . $v;
}
}
$return_headers[] = $sighead;
return $return_headers;
}
/**
* @brief set headers
*
* @param array $headers
* @return void
*/
static function set_headers($headers) {
if($headers && is_array($headers)) {
foreach($headers as $h) {
header($h);
}
}
}
/**
* @brief
*
* @param array $head
* @param string $prvkey
* @param string $alg (optional) default 'sha256'
* @return array
*/
static function sign($head, $prvkey, $alg = 'sha256') {
$ret = [];
$headers = '';
$fields = '';
logger('signing: ' . print_r($head,true), LOGGER_DATA);
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;
}
/**
* @brief
*
* @param string $header
* @return array associate array with
* - \e string \b keyID
* - \e string \b algorithm
* - \e array \b headers
* - \e string \b signature
*/
static function parse_sigheader($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;
}
/**
* @brief
*
* @param string $header
* @param string $prvkey (optional), if not set use site private key
* @return array|string associative array, empty string if failue
* - \e string \b iv
* - \e string \b key
* - \e string \b alg
* - \e string \b data
*/
static function decrypt_sigheader($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([ 'encrypted' => true, 'iv' => $iv, 'key' => $key, 'alg' => $alg, 'data' => $data ] , $prvkey);
}
return '';
}
}
|