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|
<?php
/**
* SSH2 Signature Handler
*
* PHP version 5
*
* Handles signatures in the format used by SSH2
*
* @author Jim Wigginton <terrafrost@php.net>
* @copyright 2016 Jim Wigginton
* @license http://www.opensource.org/licenses/mit-license.html MIT License
* @link http://phpseclib.sourceforge.net
*/
namespace phpseclib3\Crypt\DSA\Formats\Signature;
use phpseclib3\Common\Functions\Strings;
use phpseclib3\Math\BigInteger;
/**
* SSH2 Signature Handler
*
* @author Jim Wigginton <terrafrost@php.net>
*/
abstract class SSH2
{
/**
* Loads a signature
*
* @param string $sig
* @return mixed
*/
public static function load($sig)
{
if (!is_string($sig)) {
return false;
}
$result = Strings::unpackSSH2('ss', $sig);
if ($result === false) {
return false;
}
list($type, $blob) = $result;
if ($type != 'ssh-dss' || strlen($blob) != 40) {
return false;
}
return [
'r' => new BigInteger(substr($blob, 0, 20), 256),
's' => new BigInteger(substr($blob, 20), 256)
];
}
/**
* Returns a signature in the appropriate format
*
* @param BigInteger $r
* @param BigInteger $s
* @return string
*/
public static function save(BigInteger $r, BigInteger $s)
{
if ($r->getLength() > 160 || $s->getLength() > 160) {
return false;
}
return Strings::packSSH2(
'ss',
'ssh-dss',
str_pad($r->toBytes(), 20, "\0", STR_PAD_LEFT) .
str_pad($s->toBytes(), 20, "\0", STR_PAD_LEFT)
);
}
}
|
