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tgseclib/phpseclib/Crypt/ECDSA/Signature/SSH2.php

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2018-10-25 03:00:37 +02:00
<?php
/**
* SSH2 Signature Handler
*
* PHP version 5
*
* Handles signatures in the format used by SSH2
*
* @category Crypt
* @package Common
* @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 phpseclib\Crypt\ECDSA\Signature;
use phpseclib\Math\BigInteger;
use phpseclib\Common\Functions\Strings;
/**
* SSH2 Signature Handler
*
* @package Common
* @author Jim Wigginton <terrafrost@php.net>
* @access public
*/
abstract class SSH2
{
/**
* Loads a signature
*
* @access public
* @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) = $result;
switch ($type) {
// see https://tools.ietf.org/html/rfc5656#section-3.1.2
case 'ecdsa-sha2-nistp256':
case 'ecdsa-sha2-nistp384':
case 'ecdsa-sha2-nistp521':
break;
default:
return false;
}
$length = ceil(substr($type, 16) / 8);
return [
'r' => new BigInteger(substr($blob, 0, $length), 256),
's' => new BigInteger(substr($blob, $length), 256)
];
}
/**
* Returns a signature in the appropriate format
*
* @access public
* @param \phpseclib\Math\BigInteger $r
* @param \phpseclib\Math\BigInteger $s
* @param string $curve
* @return string
*/
public static function save(BigInteger $r, BigInteger $s, $curve)
{
switch ($curve) {
case 'nistp256':
case 'nistp384':
case 'nistp521':
break;
default:
return false;
}
$length = ceil(substr($curve, 5) / 8);
return Strings::packSSH2('ss', 'ecdsa-sha2-' . $curve,
str_pad($r->toBytes(), $length, "\0", STR_PAD_LEFT) .
str_pad($s->toBytes(), $length, "\0", STR_PAD_LEFT)
);
}
}