1<?php
  2
  3if (class_exists('ParagonIE_Sodium_Core_HChaCha20', false)) {
  4    return;
  5}
  6
  7/**
  8 * Class ParagonIE_Sodium_Core_HChaCha20
  9 */
 10class ParagonIE_Sodium_Core_HChaCha20 extends ParagonIE_Sodium_Core_ChaCha20
 11{
 12    /**
 13     * @param string $in
 14     * @param string $key
 15     * @param string|null $c
 16     * @return string
 17     *
 18     * @throws SodiumException
 19     * @throws TypeError
 20     */
 21    public static function hChaCha20($in, $key, $c = null)
 22    {
 23        if (self::strlen($in) !== 16) {
 24            throw new SodiumException('Argument 1 must be 16 bytes');
 25        }
 26        if (self::strlen($key) !== 32) {
 27            throw new SodiumException('Argument 2 must be 32 bytes');
 28        }
 29        $ctx = array();
 30
 31        if ($c === null) {
 32            $ctx[0] = 0x61707865;
 33            $ctx[1] = 0x3320646e;
 34            $ctx[2] = 0x79622d32;
 35            $ctx[3] = 0x6b206574;
 36        } else {
 37            $ctx[0] = self::load_4(self::substr($c,  0, 4));
 38            $ctx[1] = self::load_4(self::substr($c,  4, 4));
 39            $ctx[2] = self::load_4(self::substr($c,  8, 4));
 40            $ctx[3] = self::load_4(self::substr($c, 12, 4));
 41        }
 42        $ctx[4]  = self::load_4(self::substr($key,  0, 4));
 43        $ctx[5]  = self::load_4(self::substr($key,  4, 4));
 44        $ctx[6]  = self::load_4(self::substr($key,  8, 4));
 45        $ctx[7]  = self::load_4(self::substr($key, 12, 4));
 46        $ctx[8]  = self::load_4(self::substr($key, 16, 4));
 47        $ctx[9]  = self::load_4(self::substr($key, 20, 4));
 48        $ctx[10] = self::load_4(self::substr($key, 24, 4));
 49        $ctx[11] = self::load_4(self::substr($key, 28, 4));
 50        $ctx[12] = self::load_4(self::substr($in,   0, 4));
 51        $ctx[13] = self::load_4(self::substr($in,   4, 4));
 52        $ctx[14] = self::load_4(self::substr($in,   8, 4));
 53        $ctx[15] = self::load_4(self::substr($in,  12, 4));
 54        return self::hChaCha20Bytes($ctx);
 55    }
 56
 57    /**
 58     * @param array $ctx
 59     * @return string
 60     * @throws TypeError
 61     */
 62    protected static function hChaCha20Bytes(array $ctx)
 63    {
 64        $x0  = (int) $ctx[0];
 65        $x1  = (int) $ctx[1];
 66        $x2  = (int) $ctx[2];
 67        $x3  = (int) $ctx[3];
 68        $x4  = (int) $ctx[4];
 69        $x5  = (int) $ctx[5];
 70        $x6  = (int) $ctx[6];
 71        $x7  = (int) $ctx[7];
 72        $x8  = (int) $ctx[8];
 73        $x9  = (int) $ctx[9];
 74        $x10 = (int) $ctx[10];
 75        $x11 = (int) $ctx[11];
 76        $x12 = (int) $ctx[12];
 77        $x13 = (int) $ctx[13];
 78        $x14 = (int) $ctx[14];
 79        $x15 = (int) $ctx[15];
 80
 81        for ($i = 0; $i < 10; ++$i) {
 82            # QUARTERROUND( x0,  x4,  x8,  x12)
 83            list($x0, $x4, $x8, $x12) = self::quarterRound($x0, $x4, $x8, $x12);
 84
 85            # QUARTERROUND( x1,  x5,  x9,  x13)
 86            list($x1, $x5, $x9, $x13) = self::quarterRound($x1, $x5, $x9, $x13);
 87
 88            # QUARTERROUND( x2,  x6,  x10,  x14)
 89            list($x2, $x6, $x10, $x14) = self::quarterRound($x2, $x6, $x10, $x14);
 90
 91            # QUARTERROUND( x3,  x7,  x11,  x15)
 92            list($x3, $x7, $x11, $x15) = self::quarterRound($x3, $x7, $x11, $x15);
 93
 94            # QUARTERROUND( x0,  x5,  x10,  x15)
 95            list($x0, $x5, $x10, $x15) = self::quarterRound($x0, $x5, $x10, $x15);
 96
 97            # QUARTERROUND( x1,  x6,  x11,  x12)
 98            list($x1, $x6, $x11, $x12) = self::quarterRound($x1, $x6, $x11, $x12);
 99
100            # QUARTERROUND( x2,  x7,  x8,  x13)
101            list($x2, $x7, $x8, $x13) = self::quarterRound($x2, $x7, $x8, $x13);
102
103            # QUARTERROUND( x3,  x4,  x9,  x14)
104            list($x3, $x4, $x9, $x14) = self::quarterRound($x3, $x4, $x9, $x14);
105        }
106
107        return self::store32_le((int) ($x0  & 0xffffffff)) .
108            self::store32_le((int) ($x1  & 0xffffffff)) .
109            self::store32_le((int) ($x2  & 0xffffffff)) .
110            self::store32_le((int) ($x3  & 0xffffffff)) .
111            self::store32_le((int) ($x12 & 0xffffffff)) .
112            self::store32_le((int) ($x13 & 0xffffffff)) .
113            self::store32_le((int) ($x14 & 0xffffffff)) .
114            self::store32_le((int) ($x15 & 0xffffffff));
115    }
116}
117