paste.chapril.org-privatebin/lib/sjcl.php

63 lines
1.6 KiB
PHP

<?php
/**
* ZeroBin
*
* a zero-knowledge paste bin
*
* @link http://sebsauvage.net/wiki/doku.php?id=php:zerobin
* @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
* @license http://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
* @version 0.15
*/
/**
* sjcl
*
* Provides SJCL validation function.
*/
class sjcl
{
/**
* SJCL validator
*
* Checks if a json string is a proper SJCL encrypted message.
*
* @access public
* @static
* @param string $encoded JSON
* @return bool
*/
public static function isValid($encoded)
{
$accepted_keys = array('iv','salt','ct');
// Make sure content is valid json
$decoded = json_decode($encoded);
if (is_null($decoded)) return false;
$decoded = (array) $decoded;
// Make sure no additionnal keys were added.
if (
count(array_keys($decoded)) != count($accepted_keys)
) return false;
// Make sure required fields are present and contain base64 data.
foreach($accepted_keys as $k)
{
if (!(
array_key_exists($k, $decoded) &&
$ct = base64_decode($decoded[$k], $strict=true)
)) return false;
}
// Make sure some fields have a reasonable size.
if (strlen($decoded['iv']) > 24) return false;
if (strlen($decoded['salt']) > 14) return false;
// Reject data if entropy is too low
if (strlen($ct) > strlen(gzdeflate($ct))) return false;
return true;
}
}