1 <?php

     2 

     3 if (class_exists('ParagonIE_Sodium_Core_XSalsa20', false)) {

     4     return;

     5 }

     6 

     7 /**

     8  * Class ParagonIE_Sodium_Core_XSalsa20

     9  */

    10 abstract class ParagonIE_Sodium_Core_XSalsa20 extends ParagonIE_Sodium_Core_HSalsa20

    11 {

    12     /**

    13      * Expand a key and nonce into an xsalsa20 keystream.

    14      *

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

    16      *

    17      * @param int $len

    18      * @param string $nonce

    19      * @param string $key

    20      * @return string

    21      * @throws SodiumException

    22      * @throws TypeError

    23      */

    24     public static function xsalsa20($len, $nonce, $key)

    25     {

    26         $ret = self::salsa20(

    27             $len,

    28             self::substr($nonce, 16, 8),

    29             self::hsalsa20($nonce, $key)

    30         );

    31         return $ret;

    32     }

    33 

    34     /**

    35      * Encrypt a string with XSalsa20. Doesn't provide integrity.

    36      *

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

    38      *

    39      * @param string $message

    40      * @param string $nonce

    41      * @param string $key

    42      * @return string

    43      * @throws SodiumException

    44      * @throws TypeError

    45      */

    46     public static function xsalsa20_xor($message, $nonce, $key)

    47     {

    48         return self::xorStrings(

    49             $message,

    50             self::xsalsa20(

    51                 self::strlen($message),

    52                 $nonce,

    53                 $key

    54             )

    55         );

    56     }

    57 }