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63 lines
1.4 KiB
PHP
63 lines
1.4 KiB
PHP
<?php
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/**
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* PHP Power of Two Modular Exponentiation Engine
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*
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* PHP version 5 and 7
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*
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* @category Math
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* @package BigInteger
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* @author Jim Wigginton <terrafrost@php.net>
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* @copyright 2017 Jim Wigginton
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* @license http://www.opensource.org/licenses/mit-license.html MIT License
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* @link http://pear.php.net/package/Math_BigInteger
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*/
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namespace phpseclib3\Math\BigInteger\Engines\PHP\Reductions;
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use phpseclib3\Math\BigInteger\Engines\PHP\Base;
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/**
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* PHP Power Of Two Modular Exponentiation Engine
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*
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* @package PHP
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* @author Jim Wigginton <terrafrost@php.net>
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* @access public
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*/
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abstract class PowerOfTwo extends Base
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{
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/**
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* Prepare a number for use in Montgomery Modular Reductions
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*
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* @param array $x
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* @param array $n
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* @param string $class
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* @return array
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*/
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protected static function prepareReduce(array $x, array $n, $class)
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{
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return self::reduce($x, $n, $class);
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}
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/**
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* Power Of Two Reduction
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*
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* @param array $x
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* @param array $n
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* @param string $class
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* @return array
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*/
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protected static function reduce(array $x, array $n, $class)
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{
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$lhs = new $class();
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$lhs->value = $x;
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$rhs = new $class();
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$rhs->value = $n;
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$temp = new $class();
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$temp->value = [1];
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$result = $lhs->bitwise_and($rhs->subtract($temp));
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return $result->value;
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}
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} |