<?php

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

/**
 * Class ParagonIE_Sodium_Core32_ChaCha20_Ctx
 */
class ParagonIE_Sodium_Core32_ChaCha20_Ctx extends ParagonIE_Sodium_Core32_Util implements ArrayAccess
{
    /**
     * @var SplFixedArray internally, <int, ParagonIE_Sodium_Core32_Int32>
     */
    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 $counter The initial counter value.
     *                        Defaults to 8 0x00 bytes.
     * @throws InvalidArgumentException
     * @throws SodiumException
     * @throws TypeError
     */
    public function __construct($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]  = new ParagonIE_Sodium_Core32_Int32(array(0x6170, 0x7865));
        $this->container[1]  = new ParagonIE_Sodium_Core32_Int32(array(0x3320, 0x646e));
        $this->container[2]  = new ParagonIE_Sodium_Core32_Int32(array(0x7962, 0x2d32));
        $this->container[3]  = new ParagonIE_Sodium_Core32_Int32(array(0x6b20, 0x6574));

        $this->container[4]  = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($key, 0, 4));
        $this->container[5]  = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($key, 4, 4));
        $this->container[6]  = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($key, 8, 4));
        $this->container[7]  = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($key, 12, 4));
        $this->container[8]  = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($key, 16, 4));
        $this->container[9]  = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($key, 20, 4));
        $this->container[10] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($key, 24, 4));
        $this->container[11] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($key, 28, 4));

        if (empty($counter)) {
            $this->container[12] = new ParagonIE_Sodium_Core32_Int32();
            $this->container[13] = new ParagonIE_Sodium_Core32_Int32();
        } else {
            $this->container[12] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($counter, 0, 4));
            $this->container[13] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($counter, 4, 4));
        }
        $this->container[14] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($iv, 0, 4));
        $this->container[15] = ParagonIE_Sodium_Core32_Int32::fromReverseString(self::substr($iv, 4, 4));
    }

    /**
     * @internal You should not use this directly from another application
     *
     * @param int $offset
     * @param int|ParagonIE_Sodium_Core32_Int32 $value
     * @return void
     */
    #[ReturnTypeWillChange]
    public function offsetSet($offset, $value)
    {
        if (!is_int($offset)) {
            throw new InvalidArgumentException('Expected an integer');
        }
        if ($value instanceof ParagonIE_Sodium_Core32_Int32) {
            /*
        } elseif (is_int($value)) {
            $value = ParagonIE_Sodium_Core32_Int32::fromInt($value);
            */
        } else {
            throw new InvalidArgumentException('Expected an integer');
        }
        $this->container[$offset] = $value;
    }

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

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

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

• [F] Ctx.php
  Delete
• [F] IetfCtx.php
  Delete

Blog Section

Discover the Latest in Digital Payments and NFC Technology

Dive into our blog to explore the cutting-edge trends in digital payments and NFC technology. Stay updated on the innovations that are revolutionizing transactions, boosting security, and making payments quicker and more convenient. Learn how these advancements are shaping the future of financial interactions and driving the global transition towards a cashless world.

The Rise of Contactless Payments:...

In recent years, contactless payments have surged in popularity, driven...

Visit Blog

March 27, 2024

Enhancing Payment Security: The Role...

As digital transactions proliferate, ensuring robust payment security is more critical than ever. Two foundational...

Visit Blog

March 27, 2024

The Future of Digital Wallets:...

Digital wallets have fundamentally transformed how we manage money, offering a streamlined, secure, and highly...

Visit Blog

March 27, 2024