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   1  <?php
   2  
   3  /**
   4   * Class ParagonIE_Sodium_Core32_SecretStream_State
   5   */
   6  class ParagonIE_Sodium_Core32_SecretStream_State
   7  {
   8      /** @var string $key */
   9      protected $key;
  10  
  11      /** @var int $counter */
  12      protected $counter;
  13  
  14      /** @var string $nonce */
  15      protected $nonce;
  16  
  17      /** @var string $_pad */
  18      protected $_pad;
  19  
  20      /**
  21       * ParagonIE_Sodium_Core32_SecretStream_State constructor.
  22       * @param string $key
  23       * @param string|null $nonce
  24       */
  25      public function __construct($key, $nonce = null)
  26      {
  27          $this->key = $key;
  28          $this->counter = 1;
  29          if (is_null($nonce)) {
  30              $nonce = str_repeat("\0", 12);
  31          }
  32          $this->nonce = str_pad($nonce, 12, "\0", STR_PAD_RIGHT);;
  33          $this->_pad = str_repeat("\0", 4);
  34      }
  35  
  36      /**
  37       * @return self
  38       */
  39      public function counterReset()
  40      {
  41          $this->counter = 1;
  42          $this->_pad = str_repeat("\0", 4);
  43          return $this;
  44      }
  45  
  46      /**
  47       * @return string
  48       */
  49      public function getKey()
  50      {
  51          return $this->key;
  52      }
  53  
  54      /**
  55       * @return string
  56       */
  57      public function getCounter()
  58      {
  59          return ParagonIE_Sodium_Core32_Util::store32_le($this->counter);
  60      }
  61  
  62      /**
  63       * @return string
  64       */
  65      public function getNonce()
  66      {
  67          if (!is_string($this->nonce)) {
  68              $this->nonce = str_repeat("\0", 12);
  69          }
  70          if (ParagonIE_Sodium_Core32_Util::strlen($this->nonce) !== 12) {
  71              $this->nonce = str_pad($this->nonce, 12, "\0", STR_PAD_RIGHT);
  72          }
  73          return $this->nonce;
  74      }
  75  
  76      /**
  77       * @return string
  78       */
  79      public function getCombinedNonce()
  80      {
  81          return $this->getCounter() .
  82              ParagonIE_Sodium_Core32_Util::substr($this->getNonce(), 0, 8);
  83      }
  84  
  85      /**
  86       * @return self
  87       */
  88      public function incrementCounter()
  89      {
  90          ++$this->counter;
  91          return $this;
  92      }
  93  
  94      /**
  95       * @return bool
  96       */
  97      public function needsRekey()
  98      {
  99          return ($this->counter & 0xffff) === 0;
 100      }
 101  
 102      /**
 103       * @param string $newKeyAndNonce
 104       * @return self
 105       */
 106      public function rekey($newKeyAndNonce)
 107      {
 108          $this->key = ParagonIE_Sodium_Core32_Util::substr($newKeyAndNonce, 0, 32);
 109          $this->nonce = str_pad(
 110              ParagonIE_Sodium_Core32_Util::substr($newKeyAndNonce, 32),
 111              12,
 112              "\0",
 113              STR_PAD_RIGHT
 114          );
 115          return $this;
 116      }
 117  
 118      /**
 119       * @param string $str
 120       * @return self
 121       */
 122      public function xorNonce($str)
 123      {
 124          $this->nonce = ParagonIE_Sodium_Core32_Util::xorStrings(
 125              $this->getNonce(),
 126              str_pad(
 127                  ParagonIE_Sodium_Core32_Util::substr($str, 0, 8),
 128                  12,
 129                  "\0",
 130                  STR_PAD_RIGHT
 131              )
 132          );
 133          return $this;
 134      }
 135  
 136      /**
 137       * @param string $string
 138       * @return self
 139       */
 140      public static function fromString($string)
 141      {
 142          $state = new ParagonIE_Sodium_Core32_SecretStream_State(
 143              ParagonIE_Sodium_Core32_Util::substr($string, 0, 32)
 144          );
 145          $state->counter = ParagonIE_Sodium_Core32_Util::load_4(
 146              ParagonIE_Sodium_Core32_Util::substr($string, 32, 4)
 147          );
 148          $state->nonce = ParagonIE_Sodium_Core32_Util::substr($string, 36, 12);
 149          $state->_pad = ParagonIE_Sodium_Core32_Util::substr($string, 48, 8);
 150          return $state;
 151      }
 152  
 153      /**
 154       * @return string
 155       */
 156      public function toString()
 157      {
 158          return $this->key .
 159              $this->getCounter() .
 160              $this->nonce .
 161              $this->_pad;
 162      }
 163  }