<?php

if (class_exists('ParagonIE_Sodium_Core_HSalsa20', false)) {

    return;

}

/**

 * Class ParagonIE_Sodium_Core_HSalsa20

 */

abstract class ParagonIE_Sodium_Core_HSalsa20 extends ParagonIE_Sodium_Core_Salsa20

{

    /**

     * Calculate an hsalsa20 hash of a single block

     *

     * HSalsa20 doesn't have a counter and will never be used for more than

     * one block (used to derive a subkey for xsalsa20).

     *

     * @internal You should not use this directly from another application

     *

     * @param string $in

     * @param string $k

     * @param string|null $c

     * @return string

     * @throws TypeError

     */

    public static function hsalsa20($in, $k, $c = null)

    {

        if ($c === null) {

            $x0  = 0x61707865;

            $x5  = 0x3320646e;

            $x10 = 0x79622d32;

            $x15 = 0x6b206574;

        } else {

            $x0  = self::load_4(self::substr($c, 0, 4));

            $x5  = self::load_4(self::substr($c, 4, 4));

            $x10 = self::load_4(self::substr($c, 8, 4));

            $x15 = self::load_4(self::substr($c, 12, 4));

        }

        $x1  = self::load_4(self::substr($k, 0, 4));

        $x2  = self::load_4(self::substr($k, 4, 4));

        $x3  = self::load_4(self::substr($k, 8, 4));

        $x4  = self::load_4(self::substr($k, 12, 4));

        $x11 = self::load_4(self::substr($k, 16, 4));

        $x12 = self::load_4(self::substr($k, 20, 4));

        $x13 = self::load_4(self::substr($k, 24, 4));

        $x14 = self::load_4(self::substr($k, 28, 4));

        $x6  = self::load_4(self::substr($in, 0, 4));

        $x7  = self::load_4(self::substr($in, 4, 4));

        $x8  = self::load_4(self::substr($in, 8, 4));

        $x9  = self::load_4(self::substr($in, 12, 4));

        for ($i = self::ROUNDS; $i > 0; $i -= 2) {

            $x4 ^= self::rotate($x0 + $x12, 7);

            $x8 ^= self::rotate($x4 + $x0, 9);

            $x12 ^= self::rotate($x8 + $x4, 13);

            $x0 ^= self::rotate($x12 + $x8, 18);

            $x9 ^= self::rotate($x5 + $x1, 7);

            $x13 ^= self::rotate($x9 + $x5, 9);

            $x1 ^= self::rotate($x13 + $x9, 13);

            $x5 ^= self::rotate($x1 + $x13, 18);

            $x14 ^= self::rotate($x10 + $x6, 7);

            $x2 ^= self::rotate($x14 + $x10, 9);

            $x6 ^= self::rotate($x2 + $x14, 13);

            $x10 ^= self::rotate($x6 + $x2, 18);

            $x3 ^= self::rotate($x15 + $x11, 7);

            $x7 ^= self::rotate($x3 + $x15, 9);

            $x11 ^= self::rotate($x7 + $x3, 13);

            $x15 ^= self::rotate($x11 + $x7, 18);

            $x1 ^= self::rotate($x0 + $x3, 7);

            $x2 ^= self::rotate($x1 + $x0, 9);

            $x3 ^= self::rotate($x2 + $x1, 13);

            $x0 ^= self::rotate($x3 + $x2, 18);

            $x6 ^= self::rotate($x5 + $x4, 7);

            $x7 ^= self::rotate($x6 + $x5, 9);

            $x4 ^= self::rotate($x7 + $x6, 13);

            $x5 ^= self::rotate($x4 + $x7, 18);

            $x11 ^= self::rotate($x10 + $x9, 7);

            $x8 ^= self::rotate($x11 + $x10, 9);

            $x9 ^= self::rotate($x8 + $x11, 13);

            $x10 ^= self::rotate($x9 + $x8, 18);

            $x12 ^= self::rotate($x15 + $x14, 7);

            $x13 ^= self::rotate($x12 + $x15, 9);

            $x14 ^= self::rotate($x13 + $x12, 13);

            $x15 ^= self::rotate($x14 + $x13, 18);

        }

        return self::store32_le($x0) .

            self::store32_le($x5) .

            self::store32_le($x10) .

            self::store32_le($x15) .

            self::store32_le($x6) .

            self::store32_le($x7) .

            self::store32_le($x8) .

            self::store32_le($x9);

    }

}