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File: src/Core/ChaCha20/Ctx.php

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File: src/Core/ChaCha20/Ctx.php
Role: Class source
Content type: text/plain
Description: Class source
Class: PHP Sodium Compat
Cryptographic functions of libsodium in pure PHP
Author: By
Last change: Fix type assertions
Date: 1 month ago
Size: 3,876 bytes
 

Contents

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<?php

if (class_exists('ParagonIE_Sodium_Core_ChaCha20_Ctx', false)) {
    return;
}

/**
 * Class ParagonIE_Sodium_Core_ChaCha20_Ctx
 */
class ParagonIE_Sodium_Core_ChaCha20_Ctx extends ParagonIE_Sodium_Core_Util implements ArrayAccess
{
   
/**
     * @var SplFixedArray internally, <int, int>
     */
   
protected $container;

   
/**
     * ParagonIE_Sodium_Core_ChaCha20_Ctx constructor.
     *
     * @internal You should not use this directly from another application
     *
     * @param string $key ChaCha20 key.
     * @param string $iv Initialization Vector (a.k.a. nonce).
     * @param string $counter The initial counter value.
     * Defaults to 8 0x00 bytes.
     * @throws InvalidArgumentException
     * @throws TypeError
     */
   
public function __construct($key = '', $iv = '', $counter = '')
    {
        if (
self::strlen($key) !== 32) {
            throw new
InvalidArgumentException('ChaCha20 expects a 256-bit key.');
        }
        if (
self::strlen($iv) !== 8) {
            throw new
InvalidArgumentException('ChaCha20 expects a 64-bit nonce.');
        }
       
$this->container = new SplFixedArray(16);

       
/* "expand 32-byte k" as per ChaCha20 spec */
       
$this->container[0] = 0x61707865;
       
$this->container[1] = 0x3320646e;
       
$this->container[2] = 0x79622d32;
       
$this->container[3] = 0x6b206574;
       
$this->container[4] = self::load_4(self::substr($key, 0, 4));
       
$this->container[5] = self::load_4(self::substr($key, 4, 4));
       
$this->container[6] = self::load_4(self::substr($key, 8, 4));
       
$this->container[7] = self::load_4(self::substr($key, 12, 4));
       
$this->container[8] = self::load_4(self::substr($key, 16, 4));
       
$this->container[9] = self::load_4(self::substr($key, 20, 4));
       
$this->container[10] = self::load_4(self::substr($key, 24, 4));
       
$this->container[11] = self::load_4(self::substr($key, 28, 4));

        if (empty(
$counter)) {
           
$this->container[12] = 0;
           
$this->container[13] = 0;
        } else {
           
$this->container[12] = self::load_4(self::substr($counter, 0, 4));
           
$this->container[13] = self::load_4(self::substr($counter, 4, 4));
        }
       
$this->container[14] = self::load_4(self::substr($iv, 0, 4));
       
$this->container[15] = self::load_4(self::substr($iv, 4, 4));
    }

   
/**
     * @internal You should not use this directly from another application
     *
     * @param int $offset
     * @param int $value
     * @return void
     * @psalm-suppress MixedArrayOffset
     */
   
public function offsetSet($offset, $value)
    {
        if (!
is_int($offset)) {
            throw new
InvalidArgumentException('Expected an integer');
        }
        if (!
is_int($value)) {
            throw new
InvalidArgumentException('Expected an integer');
        }
       
$this->container[$offset] = $value;
    }

   
/**
     * @internal You should not use this directly from another application
     *
     * @param mixed $offset
     * @return bool
     * @psalm-suppress MixedArrayOffset
     */
   
public function offsetExists($offset)
    {
        return isset(
$this->container[$offset]);
    }

   
/**
     * @internal You should not use this directly from another application
     *
     * @param mixed $offset
     * @return void
     * @psalm-suppress MixedArrayOffset
     */
   
public function offsetUnset($offset)
    {
        unset(
$this->container[$offset]);
    }

   
/**
     * @internal You should not use this directly from another application
     *
     * @param mixed $offset
     * @return mixed|null
     * @psalm-suppress MixedArrayOffset
     */
   
public function offsetGet($offset)
    {
        return isset(
$this->container[$offset])
            ?
$this->container[$offset]
            :
null;
    }
}