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

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<?php
/**
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* PrivateBin
*
* a zero-knowledge paste bin
*
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* @link https://github.com/PrivateBin/PrivateBin
* @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
* @license https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
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* @version 1.0
*/
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namespace PrivateBin;
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/**
* 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', 'v', 'iter', 'ks', 'ts', 'mode', 'adata', 'cipher', '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, $decoded)) {
return false;
}
}
// Make sure some fields are base64 data.
if (!base64_decode($decoded['iv'], true)) {
return false;
}
if (!base64_decode($decoded['salt'], true)) {
return false;
}
if (!($ct = base64_decode($decoded['ct'], true))) {
return false;
}
// Make sure some fields have a reasonable size.
if (strlen($decoded['iv']) > 24) {
return false;
}
if (strlen($decoded['salt']) > 14) {
return false;
}
// Make sure some fields contain no unsupported values.
if (!(is_int($decoded['v']) || is_float($decoded['v'])) || (float) $decoded['v'] < 1) {
return false;
}
if (!is_int($decoded['iter']) || $decoded['iter'] <= 100) {
return false;
}
if (!in_array($decoded['ks'], array(128, 192, 256), true)) {
return false;
}
if (!in_array($decoded['ts'], array(64, 96, 128), true)) {
return false;
}
if (!in_array($decoded['mode'], array('ccm', 'ocb2', 'gcm'), true)) {
return false;
}
if ($decoded['cipher'] !== 'aes') {
return false;
}
// Reject data if entropy is too low
if (strlen($ct) > strlen(gzdeflate($ct))) {
return false;
}
return true;
}
}