Hmac.php

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<?php
#require_once 'Zend/Crypt.php';

class Zend_Crypt_Hmac extends Zend_Crypt
{

    protected static $_key = null;

    protected static $_packFormat = null;

    protected static $_hashAlgorithm = 'md5';

    protected static $_supportedMhashAlgorithms = array('adler32',' crc32', 'crc32b', 'gost',
            'haval128', 'haval160', 'haval192', 'haval256', 'md4', 'md5', 'ripemd160',
            'sha1', 'sha256', 'tiger', 'tiger128', 'tiger160');

    const STRING = 'string';
    const BINARY = 'binary';

    public static function compute($key, $hash, $data, $output = self::STRING)
    {
        // set the key
        if (!isset($key) || empty($key)) {
            #require_once 'Zend/Crypt/Hmac/Exception.php';
            throw new Zend_Crypt_Hmac_Exception('provided key is null or empty');
        }
        self::$_key = $key;

        // set the hash
        self::_setHashAlgorithm($hash);

        // perform hashing and return
        return self::_hash($data, $output);
    }

    protected static function _setHashAlgorithm($hash)
    {
        if (!isset($hash) || empty($hash)) {
            #require_once 'Zend/Crypt/Hmac/Exception.php';
            throw new Zend_Crypt_Hmac_Exception('provided hash string is null or empty');
        }

        $hash = strtolower($hash);
        $hashSupported = false;

        if (function_exists('hash_algos') && in_array($hash, hash_algos())) {
            $hashSupported = true;
        }

        if ($hashSupported === false && function_exists('mhash') && in_array($hash, self::$_supportedAlgosMhash)) {
            $hashSupported = true;
        }

        if ($hashSupported === false) {
            #require_once 'Zend/Crypt/Hmac/Exception.php';
            throw new Zend_Crypt_Hmac_Exception('hash algorithm provided is not supported on this PHP installation; please enable the hash or mhash extensions');
        }
        self::$_hashAlgorithm = $hash;
    }

    protected static function _hash($data, $output = self::STRING, $internal = false)
    {
        if (function_exists('hash_hmac')) {
            if ($output == self::BINARY) {
                return hash_hmac(self::$_hashAlgorithm, $data, self::$_key, true);
            }
            return hash_hmac(self::$_hashAlgorithm, $data, self::$_key);
        }

        if (function_exists('mhash')) {
            if ($output == self::BINARY) {
                return mhash(self::_getMhashDefinition(self::$_hashAlgorithm), $data, self::$_key);
            }
            $bin = mhash(self::_getMhashDefinition(self::$_hashAlgorithm), $data, self::$_key);
            return bin2hex($bin);
        }
    }

    protected static function _getMhashDefinition($hashAlgorithm)
    {
        for ($i = 0; $i <= mhash_count(); $i++)
        {
            $types[mhash_get_hash_name($i)] = $i;
        }
        return $types[strtoupper($hashAlgorithm)];
    }

}