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<?phpdeclare(strict_types=1);
 
 if (class_exists('ParagonIE_Sodium_Core_HChaCha20', false)) {
 return;
 }
 
 /**
 * Class ParagonIE_Sodium_Core_HChaCha20
 */
 class ParagonIE_Sodium_Core_HChaCha20 extends ParagonIE_Sodium_Core_ChaCha20
 {
 /**
 * @param string $in
 * @param string $key
 * @param string|null $c
 * @return string
 * @throws TypeError
 */
 public static function hChaCha20(
 string $in = '',
 #[SensitiveParameter]
 string $key = '',
 ?string $c = null
 ): string {
 $ctx = array();
 
 if ($c === null) {
 $ctx[0] = 0x61707865;
 $ctx[1] = 0x3320646e;
 $ctx[2] = 0x79622d32;
 $ctx[3] = 0x6b206574;
 } else {
 $ctx[0] = self::load_4(self::substr($c,  0, 4));
 $ctx[1] = self::load_4(self::substr($c,  4, 4));
 $ctx[2] = self::load_4(self::substr($c,  8, 4));
 $ctx[3] = self::load_4(self::substr($c, 12, 4));
 }
 $ctx[4]  = self::load_4(self::substr($key,  0, 4));
 $ctx[5]  = self::load_4(self::substr($key,  4, 4));
 $ctx[6]  = self::load_4(self::substr($key,  8, 4));
 $ctx[7]  = self::load_4(self::substr($key, 12, 4));
 $ctx[8]  = self::load_4(self::substr($key, 16, 4));
 $ctx[9]  = self::load_4(self::substr($key, 20, 4));
 $ctx[10] = self::load_4(self::substr($key, 24, 4));
 $ctx[11] = self::load_4(self::substr($key, 28, 4));
 $ctx[12] = self::load_4(self::substr($in,   0, 4));
 $ctx[13] = self::load_4(self::substr($in,   4, 4));
 $ctx[14] = self::load_4(self::substr($in,   8, 4));
 $ctx[15] = self::load_4(self::substr($in,  12, 4));
 return self::hChaCha20Bytes($ctx);
 }
 
 /**
 * @param array $ctx
 * @return string
 * @throws TypeError
 */
 protected static function hChaCha20Bytes(array $ctx): string
 {
 $x0  = (int) $ctx[0];
 $x1  = (int) $ctx[1];
 $x2  = (int) $ctx[2];
 $x3  = (int) $ctx[3];
 $x4  = (int) $ctx[4];
 $x5  = (int) $ctx[5];
 $x6  = (int) $ctx[6];
 $x7  = (int) $ctx[7];
 $x8  = (int) $ctx[8];
 $x9  = (int) $ctx[9];
 $x10 = (int) $ctx[10];
 $x11 = (int) $ctx[11];
 $x12 = (int) $ctx[12];
 $x13 = (int) $ctx[13];
 $x14 = (int) $ctx[14];
 $x15 = (int) $ctx[15];
 
 for ($i = 0; $i < 10; ++$i) {
 [$x0, $x4, $x8, $x12] = self::quarterRound($x0, $x4, $x8, $x12);
 [$x1, $x5, $x9, $x13] = self::quarterRound($x1, $x5, $x9, $x13);
 [$x2, $x6, $x10, $x14] = self::quarterRound($x2, $x6, $x10, $x14);
 [$x3, $x7, $x11, $x15] = self::quarterRound($x3, $x7, $x11, $x15);
 
 [$x0, $x5, $x10, $x15] = self::quarterRound($x0, $x5, $x10, $x15);
 [$x1, $x6, $x11, $x12] = self::quarterRound($x1, $x6, $x11, $x12);
 [$x2, $x7, $x8, $x13] = self::quarterRound($x2, $x7, $x8, $x13);
 [$x3, $x4, $x9, $x14] = self::quarterRound($x3, $x4, $x9, $x14);
 }
 
 return self::store32_le(($x0  & 0xffffffff)) .
 self::store32_le(($x1  & 0xffffffff)) .
 self::store32_le(($x2  & 0xffffffff)) .
 self::store32_le(($x3  & 0xffffffff)) .
 self::store32_le(($x12 & 0xffffffff)) .
 self::store32_le(($x13 & 0xffffffff)) .
 self::store32_le(($x14 & 0xffffffff)) .
 self::store32_le(($x15 & 0xffffffff));
 }
 }
 
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