<?php

/**
 * Implementation of VerificationIF for hashing a signable object
 *
 * Copyright (C) 2013 OEMR 501c3 www.oemr.org
 *
 * LICENSE: This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 3
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://opensource.org/licenses/gpl-license.php>;.
 *
 * @package OpenEMR
 * @author  Ken Chapple <ken@mi-squared.com>
 * @author  Medical Information Integration, LLC
 * @link    http://www.open-emr.org
 **/

namespace ESign;

require_once $GLOBALS['srcdir'] . '/ESign/VerificationIF.php';

class Utils_Verification implements VerificationIF
{
    public function hash($data, $algo = 'sha3-512')
    {
        $string = "";
        if (is_array($data)) {
            $string = $this->stringifyArray($data);
        } else {
            $string = $data;
        }

        if ($algo == 'sha1') {
            // support backward compatibility of prior hashes in sha1
            $hash = sha1($string);
        } else {
            $hash = hash('sha3-512', $string);
        }
        return $hash;
    }

    protected function stringifyArray(array $arr)
    {
        $string = "";
        foreach ($arr as $part) {
            if (is_array($part)) {
                $string .= $this->stringifyArray($part);
            } else {
                $string .= $part;
            }
        }

        return $string;
    }

    public function verify($data, $hash)
    {
        if (strlen($hash) < 50) {
            // support backward compatibility of prior hashes in sha1
            $currentHash = $this->hash($data, 'sha1');
        } else {
            $currentHash = $this->hash($data);
        }
        if (hash_equals($currentHash, $hash)) {
            return true;
        }

        return false;
    }
}