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Direktori : /home2/selectio/www/3-idiots/vendor/phpseclib/phpseclib/phpseclib/Math/ |
Current File : /home2/selectio/www/3-idiots/vendor/phpseclib/phpseclib/phpseclib/Math/BinaryField.php |
<?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); $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); } }