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
namespace Friendica\Util;
use Friendica\Core\Logger;
use Friendica\Model\APContact;
/**
* @brief Implements JSON-LD signatures
*
* Ported from Osada: https://framagit.org/macgirvin/osada
*/
class LDSignature
{
public static function isSigned($data)
{
return !empty($data['signature']);
}
public static function getSigner($data)
{
if (!self::isSigned($data)) {
return false;
}
$actor = JsonLD::fetchElement($data, 'actor', 'id');
if (empty($actor) || !is_string($actor)) {
return false;
}
$profile = APContact::getByURL($actor);
if (empty($profile['pubkey'])) {
return false;
}
$pubkey = $profile['pubkey'];
$ohash = self::hash(self::signableOptions($data['signature']));
$dhash = self::hash(self::signableData($data));
$x = Crypto::rsaVerify($ohash . $dhash, base64_decode($data['signature']['signatureValue']), $pubkey);
Logger::log('LD-verify: ' . intval($x));
if (empty($x)) {
return false;
} else {
return $actor;
}
}
public static function sign($data, $owner)
{
$options = [
'type' => 'RsaSignature2017',
'nonce' => Strings::getRandomHex(64),
'creator' => $owner['url'] . '#main-key',
'created' => DateTimeFormat::utcNow(DateTimeFormat::ATOM)
];
$ohash = self::hash(self::signableOptions($options));
$dhash = self::hash(self::signableData($data));
$options['signatureValue'] = base64_encode(Crypto::rsaSign($ohash . $dhash, $owner['uprvkey']));
return array_merge($data, ['signature' => $options]);
}
private static function signableData($data)
{
unset($data['signature']);
return $data;
}
private static function signableOptions($options)
{
$newopts = ['@context' => 'https://w3id.org/identity/v1'];
unset($options['type']);
unset($options['id']);
unset($options['signatureValue']);
return array_merge($newopts, $options);
}
private static function hash($obj)
{
return hash('sha256', JsonLD::normalize($obj));
}
}