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<?phpdeclare(strict_types=1);
 
 if (class_exists('ParagonIE_Sodium_Core_Salsa20', false)) {
 return;
 }
 
 /**
 * Class ParagonIE_Sodium_Core_Salsa20
 */
 abstract class ParagonIE_Sodium_Core_Salsa20 extends ParagonIE_Sodium_Core_Util
 {
 const ROUNDS = 20;
 
 /**
 * Calculate an salsa20 hash of a single block
 *
 * @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 core_salsa20(
 string $in,
 #[SensitiveParameter]
 string $k,
 ?string $c = null
 ): string {
 if (self::strlen($k) < 32) {
 throw new RangeException('Key must be 32 bytes long');
 }
 if ($c === null) {
 $j0  = $x0  = 0x61707865;
 $j5  = $x5  = 0x3320646e;
 $j10 = $x10 = 0x79622d32;
 $j15 = $x15 = 0x6b206574;
 } else {
 $j0  = $x0  = self::load_4(self::substr($c, 0, 4));
 $j5  = $x5  = self::load_4(self::substr($c, 4, 4));
 $j10 = $x10 = self::load_4(self::substr($c, 8, 4));
 $j15 = $x15 = self::load_4(self::substr($c, 12, 4));
 }
 $j1  = $x1  = self::load_4(self::substr($k, 0, 4));
 $j2  = $x2  = self::load_4(self::substr($k, 4, 4));
 $j3  = $x3  = self::load_4(self::substr($k, 8, 4));
 $j4  = $x4  = self::load_4(self::substr($k, 12, 4));
 $j6  = $x6  = self::load_4(self::substr($in, 0, 4));
 $j7  = $x7  = self::load_4(self::substr($in, 4, 4));
 $j8  = $x8  = self::load_4(self::substr($in, 8, 4));
 $j9  = $x9  = self::load_4(self::substr($in, 12, 4));
 $j11 = $x11 = self::load_4(self::substr($k, 16, 4));
 $j12 = $x12 = self::load_4(self::substr($k, 20, 4));
 $j13 = $x13 = self::load_4(self::substr($k, 24, 4));
 $j14 = $x14 = self::load_4(self::substr($k, 28, 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);
 }
 
 $x0  += $j0;
 $x1  += $j1;
 $x2  += $j2;
 $x3  += $j3;
 $x4  += $j4;
 $x5  += $j5;
 $x6  += $j6;
 $x7  += $j7;
 $x8  += $j8;
 $x9  += $j9;
 $x10 += $j10;
 $x11 += $j11;
 $x12 += $j12;
 $x13 += $j13;
 $x14 += $j14;
 $x15 += $j15;
 
 return self::store32_le($x0) .
 self::store32_le($x1) .
 self::store32_le($x2) .
 self::store32_le($x3) .
 self::store32_le($x4) .
 self::store32_le($x5) .
 self::store32_le($x6) .
 self::store32_le($x7) .
 self::store32_le($x8) .
 self::store32_le($x9) .
 self::store32_le($x10) .
 self::store32_le($x11) .
 self::store32_le($x12) .
 self::store32_le($x13) .
 self::store32_le($x14) .
 self::store32_le($x15);
 }
 
 /**
 * @internal You should not use this directly from another application
 *
 * @param int $len
 * @param string $nonce
 * @param string $key
 * @return string
 * @throws SodiumException
 * @throws TypeError
 */
 public static function salsa20(
 int $len,
 string $nonce,
 #[SensitiveParameter]
 string $key
 ): string {
 if (self::strlen($key) !== 32) {
 throw new RangeException('Key must be 32 bytes long');
 }
 $kcopy = $key;
 $in = self::substr($nonce, 0, 8) . str_repeat("\0", 8);
 $c = '';
 while ($len >= 64) {
 $c .= self::core_salsa20($in, $kcopy);
 $u = 1;
 // Internal counter.
 for ($i = 8; $i < 16; ++$i) {
 $u += self::chrToInt($in[$i]);
 $in[$i] = self::intToChr($u & 0xff);
 $u >>= 8;
 }
 $len -= 64;
 }
 if ($len > 0) {
 $c .= self::substr(
 self::core_salsa20($in, $kcopy),
 0,
 $len
 );
 }
 try {
 ParagonIE_Sodium_Compat::memzero($kcopy);
 } catch (SodiumException) {
 $kcopy = null;
 }
 return $c;
 }
 
 /**
 * @internal You should not use this directly from another application
 *
 * @param string $m
 * @param string $n
 * @param int $ic
 * @param string $k
 * @return string
 * @throws SodiumException
 * @throws TypeError
 */
 public static function salsa20_xor_ic(
 #[SensitiveParameter]
 string $m,
 string $n,
 int $ic,
 #[SensitiveParameter]
 string $k
 ): string {
 $mlen = self::strlen($m);
 if ($mlen < 1) {
 return '';
 }
 $kcopy = self::substr($k, 0, 32);
 $in = self::substr($n, 0, 8);
 // Initialize the counter
 $in .= ParagonIE_Sodium_Core_Util::store64_le($ic);
 
 $c = '';
 while ($mlen >= 64) {
 $block = self::core_salsa20($in, $kcopy);
 $c .= self::xorStrings(
 self::substr($m, 0, 64),
 self::substr($block, 0, 64)
 );
 $u = 1;
 for ($i = 8; $i < 16; ++$i) {
 $u += self::chrToInt($in[$i]);
 $in[$i] = self::intToChr($u & 0xff);
 $u >>= 8;
 }
 
 $mlen -= 64;
 $m = self::substr($m, 64);
 }
 
 if ($mlen) {
 $block = self::core_salsa20($in, $kcopy);
 $c .= self::xorStrings(
 self::substr($m, 0, $mlen),
 self::substr($block, 0, $mlen)
 );
 }
 try {
 ParagonIE_Sodium_Compat::memzero($block);
 ParagonIE_Sodium_Compat::memzero($kcopy);
 } catch (SodiumException) {
 $block = null;
 $kcopy = null;
 }
 
 return $c;
 }
 
 /**
 * @internal You should not use this directly from another application
 *
 * @param string $message
 * @param string $nonce
 * @param string $key
 * @return string
 * @throws SodiumException
 * @throws TypeError
 */
 public static function salsa20_xor(
 #[SensitiveParameter]
 string $message,
 string $nonce,
 #[SensitiveParameter]
 string $key
 ): string {
 return self::xorStrings(
 $message,
 self::salsa20(
 self::strlen($message),
 $nonce,
 $key
 )
 );
 }
 
 /**
 * @internal You should not use this directly from another application
 *
 * @param int $u
 * @param int $c
 * @return int
 */
 public static function rotate(int $u, int $c): int
 {
 $u &= 0xffffffff;
 $c %= 32;
 return (0xffffffff & (
 ($u << $c)
 |
 ($u >> (32 - $c))
 )
 );
 }
 }
 
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