103 lines
2.7 KiB
PHP
103 lines
2.7 KiB
PHP
<?php
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/**
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* PrivateBin
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*
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* a zero-knowledge paste bin
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*
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* @link https://github.com/PrivateBin/PrivateBin
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* @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
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* @license https://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
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* @version 1.2
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*/
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namespace PrivateBin;
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/**
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* Sjcl
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*
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* Provides SJCL validation function.
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*/
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class Sjcl
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{
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/**
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* SJCL validator
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*
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* Checks if a json string is a proper SJCL encrypted message.
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*
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* @access public
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* @static
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* @param string $encoded JSON
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* @return bool
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*/
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public static function isValid($encoded)
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{
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$accepted_keys = array('iv', 'v', 'iter', 'ks', 'ts', 'mode', 'adata', 'cipher', 'salt', 'ct');
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// Make sure content is valid json
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$decoded = json_decode($encoded);
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if (is_null($decoded)) {
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return false;
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}
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$decoded = (array) $decoded;
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// Make sure no additionnal keys were added.
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if (
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count(array_keys($decoded)) != count($accepted_keys)
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) {
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return false;
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}
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// Make sure required fields are present and contain base64 data.
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foreach ($accepted_keys as $k) {
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if (!array_key_exists($k, $decoded)) {
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return false;
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}
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}
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// Make sure some fields are base64 data.
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if (!base64_decode($decoded['iv'], true)) {
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return false;
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}
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if (!base64_decode($decoded['salt'], true)) {
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return false;
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}
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if (!($ct = base64_decode($decoded['ct'], true))) {
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return false;
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}
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// Make sure some fields have a reasonable size.
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if (strlen($decoded['iv']) > 24) {
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return false;
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}
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if (strlen($decoded['salt']) > 14) {
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return false;
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}
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// Make sure some fields contain no unsupported values.
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if (!(is_int($decoded['v']) || is_float($decoded['v'])) || (float) $decoded['v'] < 1) {
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return false;
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}
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if (!is_int($decoded['iter']) || $decoded['iter'] <= 100) {
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return false;
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}
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if (!in_array($decoded['ks'], array(128, 192, 256), true)) {
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return false;
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}
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if (!in_array($decoded['ts'], array(64, 96, 128), true)) {
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return false;
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}
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if (!in_array($decoded['mode'], array('ccm', 'ocb2', 'gcm'), true)) {
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return false;
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}
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if ($decoded['cipher'] !== 'aes') {
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return false;
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}
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// Reject data if entropy is too low
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if (strlen($ct) > strlen(gzdeflate($ct))) {
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return false;
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}
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return true;
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}
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}
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