Subversion Repositories oidplus

<?php

declare(strict_types=1);

namespace ParagonIE\ConstantTime;

use RangeException;

use TypeError;

/**

 *  Copyright (c) 2016 - 2022 Paragon Initiative Enterprises.

 *  Copyright (c) 2014 Steve "Sc00bz" Thomas (steve at tobtu dot com)

 *

 *  Permission is hereby granted, free of charge, to any person obtaining a copy

 *  of this software and associated documentation files (the "Software"), to deal

 *  in the Software without restriction, including without limitation the rights

 *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 *  copies of the Software, and to permit persons to whom the Software is

 *  furnished to do so, subject to the following conditions:

 *

 *  The above copyright notice and this permission notice shall be included in all

 *  copies or substantial portions of the Software.

 *

 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

 *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 *  SOFTWARE.

 */

/**

 * Class Hex

 * @package ParagonIE\ConstantTime

 */

abstract class Hex implements EncoderInterface

{

    /**

     * Convert a binary string into a hexadecimal string without cache-timing

     * leaks

     *

     * @param string $binString (raw binary)

     * @return string

     * @throws TypeError

     */

    public static function encode(string $binString): string

    {

        $hex = '';

        $len = Binary::safeStrlen($binString);

        for ($i = 0; $i < $len; ++$i) {

            /** @var array<int, int> $chunk */

            $chunk = \unpack('C', $binString[$i]);

            $c = $chunk[1] & 0xf;

            $b = $chunk[1] >> 4;

            $hex .= \pack(

                'CC',

                (87 + $b + ((($b - 10) >> 8) & ~38)),

                (87 + $c + ((($c - 10) >> 8) & ~38))

            );

        }

        return $hex;

    }

    /**

     * Convert a binary string into a hexadecimal string without cache-timing

     * leaks, returning uppercase letters (as per RFC 4648)

     *

     * @param string $binString (raw binary)

     * @return string

     * @throws TypeError

     */

    public static function encodeUpper(string $binString): string

    {

        $hex = '';

        $len = Binary::safeStrlen($binString);

        for ($i = 0; $i < $len; ++$i) {

            /** @var array<int, int> $chunk */

            $chunk = \unpack('C', $binString[$i]);

            $c = $chunk[1] & 0xf;

            $b = $chunk[1] >> 4;

            $hex .= \pack(

                'CC',

                (55 + $b + ((($b - 10) >> 8) & ~6)),

                (55 + $c + ((($c - 10) >> 8) & ~6))

            );

        }

        return $hex;

    }

    /**

     * Convert a hexadecimal string into a binary string without cache-timing

     * leaks

     *

     * @param string $encodedString

     * @param bool $strictPadding

     * @return string (raw binary)

     * @throws RangeException

     */

    public static function decode(

        string $encodedString,

        bool $strictPadding = false

    ): string {

        $hex_pos = 0;

        $bin = '';

        $c_acc = 0;

        $hex_len = Binary::safeStrlen($encodedString);

        $state = 0;

        if (($hex_len & 1) !== 0) {

            if ($strictPadding) {

                throw new RangeException(

                    'Expected an even number of hexadecimal characters'

                );

            } else {

                $encodedString = '0' . $encodedString;

                ++$hex_len;

            }

        }

        /** @var array<int, int> $chunk */

        $chunk = \unpack('C*', $encodedString);

        while ($hex_pos < $hex_len) {

            ++$hex_pos;

            $c = $chunk[$hex_pos];

            $c_num = $c ^ 48;

            $c_num0 = ($c_num - 10) >> 8;

            $c_alpha = ($c & ~32) - 55;

            $c_alpha0 = (($c_alpha - 10) ^ ($c_alpha - 16)) >> 8;

            if (($c_num0 | $c_alpha0) === 0) {

                throw new RangeException(

                    'Expected hexadecimal character'

                );

            }

            $c_val = ($c_num0 & $c_num) | ($c_alpha & $c_alpha0);

            if ($state === 0) {

                $c_acc = $c_val * 16;

            } else {

                $bin .= \pack('C', $c_acc | $c_val);

            }

            $state ^= 1;

        }

        return $bin;

    }

}