73 lines
2.3 KiB
PHP
73 lines
2.3 KiB
PHP
<?php
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/**
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* ZeroBin
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*
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* a zero-knowledge paste bin
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*
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* @link http://sebsauvage.net/wiki/doku.php?id=php:zerobin
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* @copyright 2012 Sébastien SAUVAGE (sebsauvage.net)
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* @license http://www.opensource.org/licenses/zlib-license.php The zlib/libpng License
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* @version 0.22
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*/
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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)) return false;
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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($accepted_keys)
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) return false;
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// Make sure required fields are present and contain base64 data.
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foreach($accepted_keys as $k)
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{
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if (!array_key_exists($k, $decoded)) return false;
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}
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// Make sure some fields are base64 data.
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if (!base64_decode($decoded['iv'], true)) return false;
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if (!base64_decode($decoded['salt'], true)) return false;
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if (!($ct = base64_decode($decoded['ct'], true))) return false;
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// Make sure some fields have a reasonable size.
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if (strlen($decoded['iv']) > 24) return false;
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if (strlen($decoded['salt']) > 14) return false;
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// Make sure some fields contain no unsupported values.
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if (!(is_int($decoded['v']) || is_float($decoded['v'])) || (float) $decoded['v'] < 1) return false;
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if (!is_int($decoded['iter']) || $decoded['iter'] <= 100) return false;
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if (!in_array($decoded['ks'], array(128, 192, 256), true)) return false;
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if (!in_array($decoded['ts'], array(64, 96, 128), true)) return false;
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if (!in_array($decoded['mode'], array('ccm', 'ocb2', 'gcm'), true)) return false;
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if ($decoded['cipher'] !== 'aes') return false;
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// Reject data if entropy is too low
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if (strlen($ct) > strlen(gzdeflate($ct))) return false;
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return true;
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}
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}
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