1<?php
  2
  3/**
  4 * Class ParagonIE_Sodium_Core32_SecretStream_State
  5 */
  6class 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}
164