1<?php
  2
  3if (class_exists('ParagonIE_Sodium_Core_HSalsa20', false)) {
  4    return;
  5}
  6
  7/**
  8 * Class ParagonIE_Sodium_Core_HSalsa20
  9 */
 10abstract class ParagonIE_Sodium_Core_HSalsa20 extends ParagonIE_Sodium_Core_Salsa20
 11{
 12    /**
 13     * Calculate an hsalsa20 hash of a single block
 14     *
 15     * HSalsa20 doesn't have a counter and will never be used for more than
 16     * one block (used to derive a subkey for xsalsa20).
 17     *
 18     * @internal You should not use this directly from another application
 19     *
 20     * @param string $in
 21     * @param string $k
 22     * @param string|null $c
 23     * @return string
 24     * @throws TypeError
 25     */
 26    public static function hsalsa20($in, $k, $c = null)
 27    {
 28        if ($c === null) {
 29            $x0  = 0x61707865;
 30            $x5  = 0x3320646e;
 31            $x10 = 0x79622d32;
 32            $x15 = 0x6b206574;
 33        } else {
 34            $x0  = self::load_4(self::substr($c, 0, 4));
 35            $x5  = self::load_4(self::substr($c, 4, 4));
 36            $x10 = self::load_4(self::substr($c, 8, 4));
 37            $x15 = self::load_4(self::substr($c, 12, 4));
 38        }
 39        $x1  = self::load_4(self::substr($k, 0, 4));
 40        $x2  = self::load_4(self::substr($k, 4, 4));
 41        $x3  = self::load_4(self::substr($k, 8, 4));
 42        $x4  = self::load_4(self::substr($k, 12, 4));
 43        $x11 = self::load_4(self::substr($k, 16, 4));
 44        $x12 = self::load_4(self::substr($k, 20, 4));
 45        $x13 = self::load_4(self::substr($k, 24, 4));
 46        $x14 = self::load_4(self::substr($k, 28, 4));
 47        $x6  = self::load_4(self::substr($in, 0, 4));
 48        $x7  = self::load_4(self::substr($in, 4, 4));
 49        $x8  = self::load_4(self::substr($in, 8, 4));
 50        $x9  = self::load_4(self::substr($in, 12, 4));
 51
 52        for ($i = self::ROUNDS; $i > 0; $i -= 2) {
 53            $x4 ^= self::rotate($x0 + $x12, 7);
 54            $x8 ^= self::rotate($x4 + $x0, 9);
 55            $x12 ^= self::rotate($x8 + $x4, 13);
 56            $x0 ^= self::rotate($x12 + $x8, 18);
 57            $x9 ^= self::rotate($x5 + $x1, 7);
 58            $x13 ^= self::rotate($x9 + $x5, 9);
 59            $x1 ^= self::rotate($x13 + $x9, 13);
 60            $x5 ^= self::rotate($x1 + $x13, 18);
 61            $x14 ^= self::rotate($x10 + $x6, 7);
 62            $x2 ^= self::rotate($x14 + $x10, 9);
 63            $x6 ^= self::rotate($x2 + $x14, 13);
 64            $x10 ^= self::rotate($x6 + $x2, 18);
 65            $x3 ^= self::rotate($x15 + $x11, 7);
 66            $x7 ^= self::rotate($x3 + $x15, 9);
 67            $x11 ^= self::rotate($x7 + $x3, 13);
 68            $x15 ^= self::rotate($x11 + $x7, 18);
 69            $x1 ^= self::rotate($x0 + $x3, 7);
 70            $x2 ^= self::rotate($x1 + $x0, 9);
 71            $x3 ^= self::rotate($x2 + $x1, 13);
 72            $x0 ^= self::rotate($x3 + $x2, 18);
 73            $x6 ^= self::rotate($x5 + $x4, 7);
 74            $x7 ^= self::rotate($x6 + $x5, 9);
 75            $x4 ^= self::rotate($x7 + $x6, 13);
 76            $x5 ^= self::rotate($x4 + $x7, 18);
 77            $x11 ^= self::rotate($x10 + $x9, 7);
 78            $x8 ^= self::rotate($x11 + $x10, 9);
 79            $x9 ^= self::rotate($x8 + $x11, 13);
 80            $x10 ^= self::rotate($x9 + $x8, 18);
 81            $x12 ^= self::rotate($x15 + $x14, 7);
 82            $x13 ^= self::rotate($x12 + $x15, 9);
 83            $x14 ^= self::rotate($x13 + $x12, 13);
 84            $x15 ^= self::rotate($x14 + $x13, 18);
 85        }
 86
 87        return self::store32_le($x0) .
 88            self::store32_le($x5) .
 89            self::store32_le($x10) .
 90            self::store32_le($x15) .
 91            self::store32_le($x6) .
 92            self::store32_le($x7) .
 93            self::store32_le($x8) .
 94            self::store32_le($x9);
 95    }
 96}
 97