/home/kueuepay/public_html/vendor/phpseclib/phpseclib/phpseclib/Crypt/Salsa20.php
<?php

/**
 * Pure-PHP implementation of Salsa20.
 *
 * PHP version 5
 *
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2019 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

namespace phpseclib3\Crypt;

use phpseclib3\Common\Functions\Strings;
use phpseclib3\Crypt\Common\StreamCipher;
use phpseclib3\Exception\BadDecryptionException;
use phpseclib3\Exception\InsufficientSetupException;

/**
 * Pure-PHP implementation of Salsa20.
 *
 * @author  Jim Wigginton <terrafrost@php.net>
 */
class Salsa20 extends StreamCipher
{
    /**
     * Part 1 of the state
     *
     * @var string|false
     */
    protected $p1 = false;

    /**
     * Part 2 of the state
     *
     * @var string|false
     */
    protected $p2 = false;

    /**
     * Key Length (in bytes)
     *
     * @var int
     */
    protected $key_length = 32; // = 256 bits

    /**
     * @see \phpseclib3\Crypt\Salsa20::crypt()
     */
    const ENCRYPT = 0;

    /**
     * @see \phpseclib3\Crypt\Salsa20::crypt()
     */
    const DECRYPT = 1;

    /**
     * Encryption buffer for continuous mode
     *
     * @var array
     */
    protected $enbuffer;

    /**
     * Decryption buffer for continuous mode
     *
     * @var array
     */
    protected $debuffer;

    /**
     * Counter
     *
     * @var int
     */
    protected $counter = 0;

    /**
     * Using Generated Poly1305 Key
     *
     * @var boolean
     */
    protected $usingGeneratedPoly1305Key = false;

    /**
     * Salsa20 uses a nonce
     *
     * @return bool
     */
    public function usesNonce()
    {
        return true;
    }

    /**
     * Sets the key.
     *
     * @param string $key
     * @throws \LengthException if the key length isn't supported
     */
    public function setKey($key)
    {
        switch (strlen($key)) {
            case 16:
            case 32:
                break;
            default:
                throw new \LengthException('Key of size ' . strlen($key) . ' not supported by this algorithm. Only keys of sizes 16 or 32 are supported');
        }

        parent::setKey($key);
    }

    /**
     * Sets the nonce.
     *
     * @param string $nonce
     */
    public function setNonce($nonce)
    {
        if (strlen($nonce) != 8) {
            throw new \LengthException('Nonce of size ' . strlen($key) . ' not supported by this algorithm. Only an 64-bit nonce is supported');
        }

        $this->nonce = $nonce;
        $this->changed = true;
        $this->setEngine();
    }

    /**
     * Sets the counter.
     *
     * @param int $counter
     */
    public function setCounter($counter)
    {
        $this->counter = $counter;
        $this->setEngine();
    }

    /**
     * Creates a Poly1305 key using the method discussed in RFC8439
     *
     * See https://tools.ietf.org/html/rfc8439#section-2.6.1
     */
    protected function createPoly1305Key()
    {
        if ($this->nonce === false) {
            throw new InsufficientSetupException('No nonce has been defined');
        }

        if ($this->key === false) {
            throw new InsufficientSetupException('No key has been defined');
        }

        $c = clone $this;
        $c->setCounter(0);
        $c->usePoly1305 = false;
        $block = $c->encrypt(str_repeat("\0", 256));
        $this->setPoly1305Key(substr($block, 0, 32));

        if ($this->counter == 0) {
            $this->counter++;
        }
    }

    /**
     * Setup the self::ENGINE_INTERNAL $engine
     *
     * (re)init, if necessary, the internal cipher $engine
     *
     * _setup() will be called each time if $changed === true
     * typically this happens when using one or more of following public methods:
     *
     * - setKey()
     *
     * - setNonce()
     *
     * - First run of encrypt() / decrypt() with no init-settings
     *
     * @see self::setKey()
     * @see self::setNonce()
     * @see self::disableContinuousBuffer()
     */
    protected function setup()
    {
        if (!$this->changed) {
            return;
        }

        $this->enbuffer = $this->debuffer = ['ciphertext' => '', 'counter' => $this->counter];

        $this->changed = $this->nonIVChanged = false;

        if ($this->nonce === false) {
            throw new InsufficientSetupException('No nonce has been defined');
        }

        if ($this->key === false) {
            throw new InsufficientSetupException('No key has been defined');
        }

        if ($this->usePoly1305 && !isset($this->poly1305Key)) {
            $this->usingGeneratedPoly1305Key = true;
            $this->createPoly1305Key();
        }

        $key = $this->key;
        if (strlen($key) == 16) {
            $constant = 'expand 16-byte k';
            $key .= $key;
        } else {
            $constant = 'expand 32-byte k';
        }

        $this->p1 = substr($constant, 0, 4) .
                    substr($key, 0, 16) .
                    substr($constant, 4, 4) .
                    $this->nonce .
                    "\0\0\0\0";
        $this->p2 = substr($constant, 8, 4) .
                    substr($key, 16, 16) .
                    substr($constant, 12, 4);
    }

    /**
     * Setup the key (expansion)
     */
    protected function setupKey()
    {
        // Salsa20 does not utilize this method
    }

    /**
     * Encrypts a message.
     *
     * @see \phpseclib3\Crypt\Common\SymmetricKey::decrypt()
     * @see self::crypt()
     * @param string $plaintext
     * @return string $ciphertext
     */
    public function encrypt($plaintext)
    {
        $ciphertext = $this->crypt($plaintext, self::ENCRYPT);
        if (isset($this->poly1305Key)) {
            $this->newtag = $this->poly1305($ciphertext);
        }
        return $ciphertext;
    }

    /**
     * Decrypts a message.
     *
     * $this->decrypt($this->encrypt($plaintext)) == $this->encrypt($this->encrypt($plaintext)).
     * At least if the continuous buffer is disabled.
     *
     * @see \phpseclib3\Crypt\Common\SymmetricKey::encrypt()
     * @see self::crypt()
     * @param string $ciphertext
     * @return string $plaintext
     */
    public function decrypt($ciphertext)
    {
        if (isset($this->poly1305Key)) {
            if ($this->oldtag === false) {
                throw new InsufficientSetupException('Authentication Tag has not been set');
            }
            $newtag = $this->poly1305($ciphertext);
            if ($this->oldtag != substr($newtag, 0, strlen($this->oldtag))) {
                $this->oldtag = false;
                throw new BadDecryptionException('Derived authentication tag and supplied authentication tag do not match');
            }
            $this->oldtag = false;
        }

        return $this->crypt($ciphertext, self::DECRYPT);
    }

    /**
     * Encrypts a block
     *
     * @param string $in
     */
    protected function encryptBlock($in)
    {
        // Salsa20 does not utilize this method
    }

    /**
     * Decrypts a block
     *
     * @param string $in
     */
    protected function decryptBlock($in)
    {
        // Salsa20 does not utilize this method
    }

    /**
     * Encrypts or decrypts a message.
     *
     * @see self::encrypt()
     * @see self::decrypt()
     * @param string $text
     * @param int $mode
     * @return string $text
     */
    private function crypt($text, $mode)
    {
        $this->setup();
        if (!$this->continuousBuffer) {
            if ($this->engine == self::ENGINE_OPENSSL) {
                $iv = pack('V', $this->counter) . $this->p2;
                return openssl_encrypt(
                    $text,
                    $this->cipher_name_openssl,
                    $this->key,
                    OPENSSL_RAW_DATA,
                    $iv
                );
            }
            $i = $this->counter;
            $blocks = str_split($text, 64);
            foreach ($blocks as &$block) {
                $block ^= static::salsa20($this->p1 . pack('V', $i++) . $this->p2);
            }

            return implode('', $blocks);
        }

        if ($mode == self::ENCRYPT) {
            $buffer = &$this->enbuffer;
        } else {
            $buffer = &$this->debuffer;
        }
        if (!strlen($buffer['ciphertext'])) {
            $ciphertext = '';
        } else {
            $ciphertext = $text ^ Strings::shift($buffer['ciphertext'], strlen($text));
            $text = substr($text, strlen($ciphertext));
            if (!strlen($text)) {
                return $ciphertext;
            }
        }

        $overflow = strlen($text) % 64; // & 0x3F
        if ($overflow) {
            $text2 = Strings::pop($text, $overflow);
            if ($this->engine == self::ENGINE_OPENSSL) {
                $iv = pack('V', $buffer['counter']) . $this->p2;
                // at this point $text should be a multiple of 64
                $buffer['counter'] += (strlen($text) >> 6) + 1; // ie. divide by 64
                $encrypted = openssl_encrypt(
                    $text . str_repeat("\0", 64),
                    $this->cipher_name_openssl,
                    $this->key,
                    OPENSSL_RAW_DATA,
                    $iv
                );
                $temp = Strings::pop($encrypted, 64);
            } else {
                $blocks = str_split($text, 64);
                if (strlen($text)) {
                    foreach ($blocks as &$block) {
                        $block ^= static::salsa20($this->p1 . pack('V', $buffer['counter']++) . $this->p2);
                    }
                }
                $encrypted = implode('', $blocks);
                $temp = static::salsa20($this->p1 . pack('V', $buffer['counter']++) . $this->p2);
            }
            $ciphertext .= $encrypted . ($text2 ^ $temp);
            $buffer['ciphertext'] = substr($temp, $overflow);
        } elseif (!strlen($buffer['ciphertext'])) {
            if ($this->engine == self::ENGINE_OPENSSL) {
                $iv = pack('V', $buffer['counter']) . $this->p2;
                $buffer['counter'] += (strlen($text) >> 6);
                $ciphertext .= openssl_encrypt(
                    $text,
                    $this->cipher_name_openssl,
                    $this->key,
                    OPENSSL_RAW_DATA,
                    $iv
                );
            } else {
                $blocks = str_split($text, 64);
                foreach ($blocks as &$block) {
                    $block ^= static::salsa20($this->p1 . pack('V', $buffer['counter']++) . $this->p2);
                }
                $ciphertext .= implode('', $blocks);
            }
        }

        return $ciphertext;
    }

    /**
     * Left Rotate
     *
     * @param int $x
     * @param int $n
     * @return int
     */
    protected static function leftRotate($x, $n)
    {
        if (PHP_INT_SIZE == 8) {
            $r1 = $x << $n;
            $r1 &= 0xFFFFFFFF;
            $r2 = ($x & 0xFFFFFFFF) >> (32 - $n);
        } else {
            $x = (int) $x;
            $r1 = $x << $n;
            $r2 = $x >> (32 - $n);
            $r2 &= (1 << $n) - 1;
        }
        return $r1 | $r2;
    }

    /**
     * The quarterround function
     *
     * @param int $a
     * @param int $b
     * @param int $c
     * @param int $d
     */
    protected static function quarterRound(&$a, &$b, &$c, &$d)
    {
        $b ^= self::leftRotate($a + $d, 7);
        $c ^= self::leftRotate($b + $a, 9);
        $d ^= self::leftRotate($c + $b, 13);
        $a ^= self::leftRotate($d + $c, 18);
    }

    /**
     * The doubleround function
     *
     * @param int $x0 (by reference)
     * @param int $x1 (by reference)
     * @param int $x2 (by reference)
     * @param int $x3 (by reference)
     * @param int $x4 (by reference)
     * @param int $x5 (by reference)
     * @param int $x6 (by reference)
     * @param int $x7 (by reference)
     * @param int $x8 (by reference)
     * @param int $x9 (by reference)
     * @param int $x10 (by reference)
     * @param int $x11 (by reference)
     * @param int $x12 (by reference)
     * @param int $x13 (by reference)
     * @param int $x14 (by reference)
     * @param int $x15 (by reference)
     */
    protected static function doubleRound(&$x0, &$x1, &$x2, &$x3, &$x4, &$x5, &$x6, &$x7, &$x8, &$x9, &$x10, &$x11, &$x12, &$x13, &$x14, &$x15)
    {
        // columnRound
        static::quarterRound($x0, $x4, $x8, $x12);
        static::quarterRound($x5, $x9, $x13, $x1);
        static::quarterRound($x10, $x14, $x2, $x6);
        static::quarterRound($x15, $x3, $x7, $x11);
        // rowRound
        static::quarterRound($x0, $x1, $x2, $x3);
        static::quarterRound($x5, $x6, $x7, $x4);
        static::quarterRound($x10, $x11, $x8, $x9);
        static::quarterRound($x15, $x12, $x13, $x14);
    }

    /**
     * The Salsa20 hash function function
     *
     * @param string $x
     */
    protected static function salsa20($x)
    {
        $z = $x = unpack('V*', $x);
        for ($i = 0; $i < 10; $i++) {
            static::doubleRound($z[1], $z[2], $z[3], $z[4], $z[5], $z[6], $z[7], $z[8], $z[9], $z[10], $z[11], $z[12], $z[13], $z[14], $z[15], $z[16]);
        }

        for ($i = 1; $i <= 16; $i++) {
            $x[$i] += $z[$i];
        }

        return pack('V*', ...$x);
    }

    /**
     * Calculates Poly1305 MAC
     *
     * @see self::decrypt()
     * @see self::encrypt()
     * @param string $ciphertext
     * @return string
     */
    protected function poly1305($ciphertext)
    {
        if (!$this->usingGeneratedPoly1305Key) {
            return parent::poly1305($this->aad . $ciphertext);
        } else {
            /*
            sodium_crypto_aead_chacha20poly1305_encrypt does not calculate the poly1305 tag
            the same way sodium_crypto_aead_chacha20poly1305_ietf_encrypt does. you can see
            how the latter encrypts it in Salsa20::encrypt(). here's how the former encrypts
            it:

            $this->newtag = $this->poly1305(
                $this->aad .
                pack('V', strlen($this->aad)) . "\0\0\0\0" .
                $ciphertext .
                pack('V', strlen($ciphertext)) . "\0\0\0\0"
            );

            phpseclib opts to use the IETF construction, even when the nonce is 64-bits
            instead of 96-bits
            */
            return parent::poly1305(
                self::nullPad128($this->aad) .
                self::nullPad128($ciphertext) .
                pack('V', strlen($this->aad)) . "\0\0\0\0" .
                pack('V', strlen($ciphertext)) . "\0\0\0\0"
            );
        }
    }
}
FAQ

FAQ

1. What is the Kueue Pay Payment Gateway?

The Kueue Pay Payment Gateway is an innovative technology that facilitates seamless and secure transactions between merchants and their customers. It enables businesses to accept debit and credit card payments both online and in physical stores.

2. How does the Kueue Pay Payment Gateway work?

The Kueue Pay Payment Gateway acts as a bridge between a merchant’s website or point-of-sale system and the payment processing network. It securely transmits payment information, authorizes transactions, and provides real-time status updates.

3. What is the advantage of using Kueue Pay’s Developer API?

The Kueue Pay Developer API empowers developers and entrepreneurs to integrate the Kueue Pay Payment Gateway directly into their websites or applications. This streamlines the payment process for customers and provides businesses with a customizable and efficient payment solution.

4. How can I access the Kueue Pay Developer API?

To access the Kueue Pay Developer API, you need to sign up for a developer account on our platform. Once registered, you’ll receive an API key that you can use to authenticate your API requests.

5. What types of transactions can I handle with the Kueue Pay Developer API?

The Kueue Pay Developer API allows you to initiate payments, check the status of payments, and process refunds. You can create a seamless payment experience for your customers while maintaining control over transaction management.

6. Is the Kueue Pay Developer API suitable for my business size and industry?

Yes, the Kueue Pay Developer API is designed to accommodate businesses of varying sizes and industries. Whether you’re a small online store or a large enterprise, our API can be tailored to fit your specific payment needs.

7. How user-friendly is the Kueue Pay Developer API integration process?

The Kueue Pay Developer API is designed with simplicity and ease of use in mind. Our comprehensive documentation, code samples, and developer support resources ensure a smooth integration process for any web platform.

8. Are there any fees associated with using the Kueue Pay Payment Gateway and API?

We offer competitive pricing plans for using the Kueue Pay Payment Gateway and Developer API. Details about fees and pricing tiers can be found on our developer portal.

9. Can I customize the payment experience for my customers using the Kueue Pay API?

Absolutely, the Kueue Pay Developer API offers customization options that allow you to tailor the payment experience to match your brand and user interface. You can create a seamless and cohesive payment journey for your customers.

10. What kind of support is available if I encounter issues during API integration?

We provide dedicated developer support to assist you with any issues or questions you may have during the API integration process. Reach out to our support team at developersupport@NFCPay.com for prompt assistance.

Remember, our goal is to empower your business with a robust and efficient payment solution. If you have any additional questions or concerns, feel free to explore our developer portal or contact our support team.