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   1  <?php
   2  
   3  if (!defined('SODIUM_COMPAT_AEGIS_C0')) {
   4      define('SODIUM_COMPAT_AEGIS_C0', "\x00\x01\x01\x02\x03\x05\x08\x0d\x15\x22\x37\x59\x90\xe9\x79\x62");
   5  }
   6  if (!defined('SODIUM_COMPAT_AEGIS_C1')) {
   7      define('SODIUM_COMPAT_AEGIS_C1', "\xdb\x3d\x18\x55\x6d\xc2\x2f\xf1\x20\x11\x31\x42\x73\xb5\x28\xdd");
   8  }
   9  
  10  class ParagonIE_Sodium_Core_AEGIS128L extends ParagonIE_Sodium_Core_AES
  11  {
  12      /**
  13       * @param string $ct
  14       * @param string $tag
  15       * @param string $ad
  16       * @param string $key
  17       * @param string $nonce
  18       * @return string
  19       * @throws SodiumException
  20       */
  21      public static function decrypt($ct, $tag, $ad, $key, $nonce)
  22      {
  23          $state = self::init($key, $nonce);
  24          $ad_blocks = (self::strlen($ad) + 31) >> 5;
  25          for ($i = 0; $i < $ad_blocks; ++$i) {
  26              $ai = self::substr($ad, $i << 5, 32);
  27              if (self::strlen($ai) < 32) {
  28                  $ai = str_pad($ai, 32, "\0", STR_PAD_RIGHT);
  29              }
  30              $state->absorb($ai);
  31          }
  32  
  33          $msg = '';
  34          $cn = self::strlen($ct) & 31;
  35          $ct_blocks = self::strlen($ct) >> 5;
  36          for ($i = 0; $i < $ct_blocks; ++$i) {
  37              $msg .= $state->dec(self::substr($ct, $i << 5, 32));
  38          }
  39          if ($cn) {
  40              $start = $ct_blocks << 5;
  41              $msg .= $state->decPartial(self::substr($ct, $start, $cn));
  42          }
  43          $expected_tag = $state->finalize(
  44              self::strlen($ad) << 3,
  45              self::strlen($msg) << 3
  46          );
  47          if (!self::hashEquals($expected_tag, $tag)) {
  48              try {
  49                  // The RFC says to erase msg, so we shall try:
  50                  ParagonIE_Sodium_Compat::memzero($msg);
  51              } catch (SodiumException $ex) {
  52                  // Do nothing if we cannot memzero
  53              }
  54              throw new SodiumException('verification failed');
  55          }
  56          return $msg;
  57      }
  58  
  59      /**
  60       * @param string $msg
  61       * @param string $ad
  62       * @param string $key
  63       * @param string $nonce
  64       * @return array
  65       *
  66       * @throws SodiumException
  67       */
  68      public static function encrypt($msg, $ad, $key, $nonce)
  69      {
  70          $state = self::init($key, $nonce);
  71          // ad_blocks = Split(ZeroPad(ad, 256), 256)
  72          // for ai in ad_blocks:
  73          //     Absorb(ai)
  74          $ad_len = self::strlen($ad);
  75          $msg_len = self::strlen($msg);
  76          $ad_blocks = ($ad_len + 31) >> 5;
  77          for ($i = 0; $i < $ad_blocks; ++$i) {
  78              $ai = self::substr($ad, $i << 5, 32);
  79              if (self::strlen($ai) < 32) {
  80                  $ai = str_pad($ai, 32, "\0", STR_PAD_RIGHT);
  81              }
  82              $state->absorb($ai);
  83          }
  84  
  85          // msg_blocks = Split(ZeroPad(msg, 256), 256)
  86          // for xi in msg_blocks:
  87          //     ct = ct || Enc(xi)
  88          $ct = '';
  89          $msg_blocks = ($msg_len + 31) >> 5;
  90          for ($i = 0; $i < $msg_blocks; ++$i) {
  91              $xi = self::substr($msg, $i << 5, 32);
  92              if (self::strlen($xi) < 32) {
  93                  $xi = str_pad($xi, 32, "\0", STR_PAD_RIGHT);
  94              }
  95              $ct .= $state->enc($xi);
  96          }
  97          // tag = Finalize(|ad|, |msg|)
  98          // ct = Truncate(ct, |msg|)
  99          $tag = $state->finalize(
 100              $ad_len << 3,
 101              $msg_len << 3
 102          );
 103          // return ct and tag
 104          return array(
 105              self::substr($ct, 0, $msg_len),
 106              $tag
 107          );
 108      }
 109  
 110      /**
 111       * @param string $key
 112       * @param string $nonce
 113       * @return ParagonIE_Sodium_Core_AEGIS_State128L
 114       */
 115      public static function init($key, $nonce)
 116      {
 117          return ParagonIE_Sodium_Core_AEGIS_State128L::init($key, $nonce);
 118      }
 119  }