64 lines
1.9 KiB
PHP
64 lines
1.9 KiB
PHP
<?php
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/**
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* OpenSSL Modular Exponentiation Engine
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*
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* PHP version 5 and 7
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*
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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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declare(strict_types=1);
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namespace phpseclib3\Math\BigInteger\Engines;
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use phpseclib3\Crypt\RSA\Formats\Keys\PKCS8;
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use phpseclib3\Math\BigInteger;
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/**
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* OpenSSL Modular Exponentiation Engine
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*
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* @author Jim Wigginton <terrafrost@php.net>
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*/
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abstract class OpenSSL
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{
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/**
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* Test for engine validity
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*/
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public static function isValidEngine(): bool
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{
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return extension_loaded('openssl') && static::class != __CLASS__;
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}
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/**
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* Performs modular exponentiation.
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*/
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public static function powModHelper(Engine $x, Engine $e, Engine $n): Engine
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{
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if ($n->getLengthInBytes() < 31 || $n->getLengthInBytes() > 16384) {
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throw new \OutOfRangeException('Only modulo between 31 and 16384 bits are accepted');
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}
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$key = PKCS8::savePublicKey(
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new BigInteger($n),
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new BigInteger($e)
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);
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$plaintext = str_pad($x->toBytes(), $n->getLengthInBytes(), "\0", STR_PAD_LEFT);
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// this is easily prone to failure. if the modulo is a multiple of 2 or 3 or whatever it
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// won't work and you'll get a "failure: error:0906D06C:PEM routines:PEM_read_bio:no start line"
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// error. i suppose, for even numbers, we could do what PHP\Montgomery.php does, but then what
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// about odd numbers divisible by 3, by 5, etc?
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if (!openssl_public_encrypt($plaintext, $result, $key, OPENSSL_NO_PADDING)) {
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throw new \UnexpectedValueException(openssl_error_string());
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}
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$class = $x::class;
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return new $class($result, 256);
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}
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}
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