Friendica Communications Platform (please note that this is a clone of the repository at github, issues are handled there) https://friendi.ca
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<?php
/**
* @file src/Util/HTTPSignature.php
*/
namespace Friendica\Util;
use Friendica\Core\Config;
use Friendica\Database\DBA;
/**
* @brief Implements HTTP Signatures per draft-cavage-http-signatures-07.
*
* Ported from Hubzilla: https://framagit.org/hubzilla/core/blob/master/Zotlabs/Web/HTTPSig.php
*
* @see https://tools.ietf.org/html/draft-cavage-http-signatures-07
*/
class HTTPSignature
{
/**
* @brief RFC5843
*
* Disabled until Friendica's ActivityPub implementation
* is ready.
*
* @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->fetch();
$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)) {
$result['signer'] = $sig_block['keyId'];
$key = $key($sig_block['keyId']);
}
// We don't use Activity Pub at the moment.
// if (!$key) {
// $result['signer'] = $sig_block['keyId'];
// $key = self::getActivitypubKey($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 $result;
}
/**
* Fetch the public key for Activity Pub contact.
*
* @param string|int The identifier (contact addr or contact ID).
* @return string|boolean The public key or false on failure.
*/
private static function getActivitypubKey($id)
{
if (strpos($id, 'acct:') === 0) {
$contact = DBA::selectFirst('contact', ['pubkey'], ['uid' => 0, 'addr' => str_replace('acct:', '', $id)]);
} else {
$contact = DBA::selectFirst('contact', ['pubkey'], ['id' => $id, 'network' => 'activitypub']);
}
if (DBA::isResult($contact)) {
return $contact['pubkey'];
}
if(function_exists('as_fetch')) {
$r = as_fetch($id);
}
if ($r) {
$j = json_decode($r, true);
if (array_key_exists('publicKey', $j) && array_key_exists('publicKeyPem', $j['publicKey'])) {
if ((array_key_exists('id', $j['publicKey']) && $j['publicKey']['id'] !== $id) && $j['id'] !== $id) {
return false;
}
return $j['publicKey']['publicKeyPem'];
}
}
return false;
}
/**
* @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) {
// This is for ActivityPub implementation.
// Since the Activity Pub implementation isn't
// ready at the moment, we comment it out.
// header($k . ': ' . $v);
} else {
$return_headers[] = $k . ': ' . $v;
}
}
}
if ($send_headers) {
// This is for ActivityPub implementation.
// Since the Activity Pub implementation isn't
// ready at the moment, we comment it out.
// 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 '';
}
}