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<?php
namespace Zotlabs\Lib;
require_once('library/jsonld/jsonld.php');
class LDSignatures {
static function verify($data,$pubkey) {
$ohash = self::hash(self::signable_options($data['signature']));
$dhash = self::hash(self::signable_data($data));
return rsa_verify($ohash . $dhash,base64_decode($data['signature']['signatureValue']), $pubkey);
}
static function dopplesign(&$data,$channel) {
$data['magicEnv'] = self::salmon_sign($data,$channel);
return self::sign($data,$channel);
}
static function sign($data,$channel) {
$options = [
'type' => 'RsaSignature2017',
'nonce' => random_string(64),
'creator' => z_root() . '/channel/' . $channel['channel_address'] . '/public_key_pem',
'created' => datetime_convert('UTC','UTC', 'now', 'Y-m-d\Th:i:s\Z')
];
$ohash = self::hash(self::signable_options($options));
$dhash = self::hash(self::signable_data($data));
$options['signatureValue'] = base64_encode(rsa_sign($ohash . $dhash,$channel['channel_prvkey']));
$signed = array_merge([
'@context' => [ 'https://www.w3.org/ns/activitystreams', 'https://w3id.org/security/v1' ],
],$options);
return $signed;
}
static function signable_data($data) {
$newdata = [];
if($data) {
foreach($data as $k => $v) {
if(! in_array($k,[ 'signature' ])) {
$newopts[$k] = $v;
}
}
}
return json_encode($newdata,JSON_UNESCAPED_SLASHES);
}
static function signable_options($options) {
$newopts = [ '@context' => 'https://w3id.org/identity/v1' ];
if($options) {
foreach($options as $k => $v) {
if(! in_array($k,[ 'type','id','signatureValue' ])) {
$newopts[$k] = $v;
}
}
}
return json_encode($newopts,JSON_UNESCAPED_SLASHES);
}
static function hash($obj) {
return hash('sha256',self::normalise($obj));
}
static function normalise($data) {
if(is_string($data)) {
$data = json_decode($data);
}
if(! is_object($data))
return '';
return jsonld_normalize($data,[ 'algorithm' => 'URDNA2015', 'format' => 'application/nquads' ]);
}
static function salmon_sign($data,$channel) {
$data = json_encode($data,JSON_UNESCAPED_SLASHES);
$data = base64url_encode($data, false); // do not strip padding
$data_type = 'application/activity+json';
$encoding = 'base64url';
$algorithm = 'RSA-SHA256';
$keyhash = base64url_encode(z_root() . '/channel/' . $channel['channel_address']);
$data = str_replace(array(" ","\t","\r","\n"),array("","","",""),$data);
// precomputed base64url encoding of data_type, encoding, algorithm concatenated with periods
$precomputed = '.' . base64url_encode($data_type,false) . '.YmFzZTY0dXJs.UlNBLVNIQTI1Ng==';
$signature = base64url_encode(rsa_sign($data . $precomputed,$channel['channel_prvkey']));
return ([
'meData' => $data,
'meDataType' => $data_type,
'meEncoding' => $encoding,
'meAlgorithm' => $algorithm,
'meCreator' => z_root() . '/channel/' . $channel['channel_address'] . '/public_key_pem',
'meSignatureValue' => $signature
]);
}
}
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