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| Rev | Author | Line No. | Line |
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| 827 | daniel-mar | 1 | <?php |
| 2 | |||
| 3 | /** |
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| 4 | * Modular Exponentiation Engine |
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| 5 | * |
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| 6 | * PHP version 5 and 7 |
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| 7 | * |
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| 874 | daniel-mar | 8 | * @category Math |
| 9 | * @package BigInteger |
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| 827 | daniel-mar | 10 | * @author Jim Wigginton <terrafrost@php.net> |
| 11 | * @copyright 2017 Jim Wigginton |
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| 12 | * @license http://www.opensource.org/licenses/mit-license.html MIT License |
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| 13 | * @link http://pear.php.net/package/Math_BigInteger |
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| 14 | */ |
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| 15 | |||
| 16 | namespace phpseclib3\Math\BigInteger\Engines\BCMath; |
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| 17 | |||
| 18 | use phpseclib3\Math\BigInteger\Engines\BCMath; |
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| 19 | |||
| 20 | /** |
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| 21 | * Sliding Window Exponentiation Engine |
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| 22 | * |
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| 874 | daniel-mar | 23 | * @package PHP |
| 827 | daniel-mar | 24 | * @author Jim Wigginton <terrafrost@php.net> |
| 874 | daniel-mar | 25 | * @access public |
| 827 | daniel-mar | 26 | */ |
| 27 | abstract class Base extends BCMath |
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| 28 | { |
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| 29 | /** |
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| 30 | * Cache constants |
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| 31 | * |
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| 32 | * $cache[self::VARIABLE] tells us whether or not the cached data is still valid. |
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| 33 | * |
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| 874 | daniel-mar | 34 | * @access private |
| 827 | daniel-mar | 35 | */ |
| 36 | const VARIABLE = 0; |
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| 37 | /** |
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| 38 | * $cache[self::DATA] contains the cached data. |
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| 39 | * |
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| 874 | daniel-mar | 40 | * @access private |
| 827 | daniel-mar | 41 | */ |
| 42 | const DATA = 1; |
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| 43 | |||
| 44 | /** |
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| 45 | * Test for engine validity |
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| 46 | * |
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| 47 | * @return bool |
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| 48 | */ |
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| 49 | public static function isValidEngine() |
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| 50 | { |
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| 51 | return static::class != __CLASS__; |
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| 52 | } |
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| 53 | |||
| 54 | /** |
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| 55 | * Performs modular exponentiation. |
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| 56 | * |
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| 57 | * @param BCMath $x |
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| 58 | * @param BCMath $e |
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| 59 | * @param BCMath $n |
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| 60 | * @param string $class |
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| 61 | * @return BCMath |
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| 62 | */ |
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| 63 | protected static function powModHelper(BCMath $x, BCMath $e, BCMath $n, $class) |
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| 64 | { |
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| 65 | if (empty($e->value)) { |
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| 66 | $temp = new $class(); |
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| 67 | $temp->value = '1'; |
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| 68 | return $x->normalize($temp); |
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| 69 | } |
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| 70 | |||
| 71 | return $x->normalize(static::slidingWindow($x, $e, $n, $class)); |
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| 72 | } |
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| 73 | |||
| 74 | /** |
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| 75 | * Modular reduction preparation |
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| 76 | * |
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| 77 | * @param string $x |
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| 78 | * @param string $n |
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| 79 | * @param string $class |
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| 80 | * @see self::slidingWindow() |
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| 81 | * @return string |
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| 82 | */ |
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| 83 | protected static function prepareReduce($x, $n, $class) |
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| 84 | { |
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| 85 | return static::reduce($x, $n); |
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| 86 | } |
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| 87 | |||
| 88 | /** |
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| 89 | * Modular multiply |
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| 90 | * |
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| 91 | * @param string $x |
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| 92 | * @param string $y |
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| 93 | * @param string $n |
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| 94 | * @param string $class |
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| 95 | * @see self::slidingWindow() |
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| 96 | * @return string |
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| 97 | */ |
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| 98 | protected static function multiplyReduce($x, $y, $n, $class) |
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| 99 | { |
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| 100 | return static::reduce(bcmul($x, $y), $n); |
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| 101 | } |
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| 102 | |||
| 103 | /** |
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| 104 | * Modular square |
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| 105 | * |
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| 106 | * @param string $x |
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| 107 | * @param string $n |
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| 108 | * @param string $class |
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| 109 | * @see self::slidingWindow() |
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| 110 | * @return string |
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| 111 | */ |
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| 112 | protected static function squareReduce($x, $n, $class) |
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| 113 | { |
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| 114 | return static::reduce(bcmul($x, $x), $n); |
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| 115 | } |
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| 116 | } |