<?php

/**
 * Binary Finite Fields
 *
 * Utilizes the factory design pattern
 *
 * PHP version 5 and 7
 *
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2017 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 */

namespace phpseclib3\Math;

use phpseclib3\Common\Functions\Strings;
use phpseclib3\Math\BinaryField\Integer;
use phpseclib3\Math\Common\FiniteField;

/**
 * Binary Finite Fields
 *
 * @author  Jim Wigginton <terrafrost@php.net>
 */
class BinaryField extends FiniteField
{
    /**
     * Instance Counter
     *
     * @var int
     */
    private static $instanceCounter = 0;

    /**
     * Keeps track of current instance
     *
     * @var int
     */
    protected $instanceID;

    /** @var BigInteger */
    private $randomMax;

    /**
     * Default constructor
     */
    public function __construct(...$indices)
    {
        $m = array_shift($indices);
        if ($m > 571) {
            /* sect571r1 and sect571k1 are the largest binary curves that https://www.secg.org/sec2-v2.pdf defines
               altho theoretically there may be legit reasons to use binary finite fields with larger degrees
               imposing a limit on the maximum size is both reasonable and precedented. in particular,
               http://tools.ietf.org/html/rfc4253#section-6.1 (The Secure Shell (SSH) Transport Layer Protocol) says
               "implementations SHOULD check that the packet length is reasonable in order for the implementation to
                avoid denial of service and/or buffer overflow attacks" */
            throw new \OutOfBoundsException('Degrees larger than 571 are not supported');
        }
        $val = str_repeat('0', $m) . '1';
        foreach ($indices as $index) {
            $val[$index] = '1';
        }
        $modulo = static::base2ToBase256(strrev($val));

        $mStart = 2 * $m - 2;
        $t = ceil($m / 8);
        $finalMask = chr((1 << ($m % 8)) - 1);
        if ($finalMask == "\0") {
            $finalMask = "\xFF";
        }
        $bitLen = $mStart + 1;
        $pad = ceil($bitLen / 8);
        $h = $bitLen & 7;
        $h = $h ? 8 - $h : 0;

        $r = rtrim(substr($val, 0, -1), '0');
        $u = [static::base2ToBase256(strrev($r))];
        for ($i = 1; $i < 8; $i++) {
            $u[] = static::base2ToBase256(strrev(str_repeat('0', $i) . $r));
        }

        // implements algorithm 2.40 (in section 2.3.5) in "Guide to Elliptic Curve Cryptography"
        // with W = 8
        $reduce = function ($c) use ($u, $mStart, $m, $t, $finalMask, $pad, $h) {
            $c = str_pad($c, $pad, "\0", STR_PAD_LEFT);
            for ($i = $mStart; $i >= $m;) {
                $g = $h >> 3;
                $mask = $h & 7;
                $mask = $mask ? 1 << (7 - $mask) : 0x80;
                for (; $mask > 0; $mask >>= 1, $i--, $h++) {
                    if (ord($c[$g]) & $mask) {
                        $temp = $i - $m;
                        $j = $temp >> 3;
                        $k = $temp & 7;
                        $t1 = $j ? substr($c, 0, -$j) : $c;
                        $length = strlen($t1);
                        if ($length) {
                            $t2 = str_pad($u[$k], $length, "\0", STR_PAD_LEFT);
                            $temp = $t1 ^ $t2;
                            $c = $j ? substr_replace($c, $temp, 0, $length) : $temp;
                        }
                    }
                }
            }
            $c = substr($c, -$t);
            if (strlen($c) == $t) {
                $c[0] = $c[0] & $finalMask;
            }
            return ltrim($c, "\0");
        };

        $this->instanceID = self::$instanceCounter++;
        Integer::setModulo($this->instanceID, $modulo);
        Integer::setRecurringModuloFunction($this->instanceID, $reduce);

        $this->randomMax = new BigInteger($modulo, 2);
    }

    /**
     * Returns an instance of a dynamically generated PrimeFieldInteger class
     *
     * @param string $num
     * @return Integer
     */
    public function newInteger($num)
    {
        return new Integer($this->instanceID, $num instanceof BigInteger ? $num->toBytes() : $num);
    }

    /**
     * Returns an integer on the finite field between one and the prime modulo
     *
     * @return Integer
     */
    public function randomInteger()
    {
        static $one;
        if (!isset($one)) {
            $one = new BigInteger(1);
        }

        return new Integer($this->instanceID, BigInteger::randomRange($one, $this->randomMax)->toBytes());
    }

    /**
     * Returns the length of the modulo in bytes
     *
     * @return int
     */
    public function getLengthInBytes()
    {
        return strlen(Integer::getModulo($this->instanceID));
    }

    /**
     * Returns the length of the modulo in bits
     *
     * @return int
     */
    public function getLength()
    {
        return strlen(Integer::getModulo($this->instanceID)) << 3;
    }

    /**
     * Converts a base-2 string to a base-256 string
     *
     * @param string $x
     * @param int|null $size
     * @return string
     */
    public static function base2ToBase256($x, $size = null)
    {
        $str = Strings::bits2bin($x);

        $pad = strlen($x) >> 3;
        if (strlen($x) & 3) {
            $pad++;
        }
        $str = str_pad($str, $pad, "\0", STR_PAD_LEFT);
        if (isset($size)) {
            $str = str_pad($str, $size, "\0", STR_PAD_LEFT);
        }

        return $str;
    }

    /**
     * Converts a base-256 string to a base-2 string
     *
     * @param string $x
     * @return string
     */
    public static function base256ToBase2($x)
    {
        if (function_exists('gmp_import')) {
            return gmp_strval(gmp_import($x), 2);
        }

        return Strings::bin2bits($x);
    }
}

• [D] BigInteger
• [D] BinaryField
• [D] Common
• [D] PrimeField
• [F] BigInteger.php
  Delete
• [F] BinaryField.php
  Delete
• [F] PrimeField.php
  Delete

Secure, Swift, and Smart Payments with NFCPay !

With NFC Pay, experience seamless and secure transactions right at your fingertips. Add your cards, load your wallet, and make payments effortlessly. Activate your merchant account to receive payments or transfer money instantly to other users. NFC Pay combines security, speed, and smart features, making every transaction smooth and reliable. Embrace the future of payments with NFC Pay.

2320

Total User

2320

Happy User

Our Best Customer

How it Works

Quick Steps to NFC Pay

Getting started with NFC Pay is simple and quick. Register your account, add your cards, and you're ready to make payments in no time. Whether you're paying at a store, sending money to a friend, or managing your merchant transactions, NFC Pay makes it easy and secure.

1

Register Your Account

Download the NFC Pay app and sign up with your email or phone number. Complete the registration process by verifying your identity, and set up your secure PIN to protect your account.

2

Add Your Cards

Link your debit or credit cards to your NFC Pay wallet. Simply scan your card or enter the details manually, and you’re set to load funds, shop, and pay with ease.

3

Make Payment

To pay, simply tap your phone or scan the QR code at checkout. You can also transfer money to other users with a few taps. Enjoy fast, contactless payments with top-notch security.

Security System

Advanced Security Features Designed to Protect Your Information Effectively

NFC Pay prioritizes your security with advanced features that safeguard every transaction. From SMS or email verification to end-to-end encryption, we've implemented robust measures to ensure your data is always protected. Our security systems are designed to prevent unauthorized access and provide you with a safe and reliable payment experience.

SMS or Email Verification

Receive instant alerts for every transaction to keep track of your account activities.

KYC Solution

Verify your identity through our Know Your Customer process to prevent fraud and enhance security.

Two Factor Authentication

Dramatically supply transparent backward deliverables before caward comp internal or "organic" sources.

End-to-End Encryption

All your data and transactions are encrypted, ensuring that your sensitive information remains private.

Behavior Tracking

Monitor unusual activity patterns to detect and prevent suspicious behavior in real-time.

Why Choice Us

Top Reasons to Choose Us for Reliable and Expert Solutions

With NFC Pay, you get a trusted platform backed by proven expertise and a commitment to quality. We put our customers first, offering innovative solutions tailored to your needs, ensuring every transaction is secure, swift, and seamless.

1

Proven Expertise

Our team brings years of experience in the digital payments industry to provide reliable services.

2

Commitment to Quality

We prioritize excellence, ensuring that every aspect of our platform meets the highest standards.

3

Customer-Centric Approach

Your needs drive our solutions, and we are dedicated to delivering a superior user experience.

4

Innovative Solutions

We continuously evolve, integrating the latest technologies to enhance your payment experience.

Testimonial Section

Customer Feedback: Real Experiences from Satisfied Clients and Partners

Hear from our users who trust NFC Pay for their everyday transactions. Our commitment to security, ease of use, and exceptional service shines through in their experiences. See why our clients choose NFC Pay for their payment needs and how it has transformed the way they manage their finances.

"NFC Pay has made my transactions incredibly simple and secure. The intuitive interface and quick payment options are game-changers for my business"

Sophia Martinez

"I love how NFC Pay prioritizes security without compromising on convenience. The two-factor authentication and instant alerts give me peace of mind every time I use it."

Emily Clark

"Setting up my merchant account was a breeze, and now I can accept payments effortlessly. NFC Pay has truly streamlined my operations, saving me time and hassle."

John Carter

App Section

Get the NFC Pay App for Seamless Transactions Anytime, Anywhere

Unlock the full potential of NFC Pay by downloading our app, designed to bring secure, swift, and smart transactions to your fingertips. Whether you're paying at a store, transferring money to friends, or managing your business payments, the NFC Pay app makes it effortless. Available on both iOS and Android, it's your all-in-one solution for convenient and reliable digital payments. Download now and experience the future of payments!

Get it on

Google Pay

Download On The

Apple Store