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gnu-social/plugins/OStatus/extlib/Math/BigInteger.php

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Adding Crypt library from http://phpseclib.sourceforge.net/
2010-03-13 00:34:24 +00:00
<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/**
* Pure-PHP arbitrary precision integer arithmetic library.
*
* Supports base-2, base-10, base-16, and base-256 numbers. Uses the GMP or BCMath extensions, if available,
* and an internal implementation, otherwise.
*
* PHP versions 4 and 5
*
* {@internal (all DocBlock comments regarding implementation - such as the one that follows - refer to the
* {@link MATH_BIGINTEGER_MODE_INTERNAL MATH_BIGINTEGER_MODE_INTERNAL} mode)
*
* Math_BigInteger uses base-2**26 to perform operations such as multiplication and division and
* base-2**52 (ie. two base 2**26 digits) to perform addition and subtraction. Because the largest possible
* value when multiplying two base-2**26 numbers together is a base-2**52 number, double precision floating
* point numbers - numbers that should be supported on most hardware and whose significand is 53 bits - are
* used. As a consequence, bitwise operators such as >> and << cannot be used, nor can the modulo operator %,
* which only supports integers. Although this fact will slow this library down, the fact that such a high
* base is being used should more than compensate.
*
* When PHP version 6 is officially released, we'll be able to use 64-bit integers. This should, once again,
* allow bitwise operators, and will increase the maximum possible base to 2**31 (or 2**62 for addition /
* subtraction).
*
* Useful resources are as follows:
*
* - {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf Handbook of Applied Cryptography (HAC)}
* - {@link http://math.libtomcrypt.com/files/tommath.pdf Multi-Precision Math (MPM)}
* - Java's BigInteger classes. See /j2se/src/share/classes/java/math in jdk-1_5_0-src-jrl.zip
*
* One idea for optimization is to use the comba method to reduce the number of operations performed.
* MPM uses this quite extensively. The following URL elaborates:
*
* {@link http://www.everything2.com/index.pl?node_id=1736418}}}
*
* Here's an example of how to use this library:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger(2);
* $b = new Math_BigInteger(3);
*
* $c = $a->add($b);
*
* echo $c->toString(); // outputs 5
* ?>
* </code>
*
* LICENSE: This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
* @category Math
* @package Math_BigInteger
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVI Jim Wigginton
* @license http://www.gnu.org/licenses/lgpl.txt
* @version $Id: BigInteger.php,v 1.18 2009/12/04 19:12:18 terrafrost Exp $
* @link http://pear.php.net/package/Math_BigInteger
*/
/**#@+
* @access private
* @see Math_BigInteger::_slidingWindow()
*/
/**
* @see Math_BigInteger::_montgomery()
* @see Math_BigInteger::_prepMontgomery()
*/
define('MATH_BIGINTEGER_MONTGOMERY', 0);
/**
* @see Math_BigInteger::_barrett()
*/
define('MATH_BIGINTEGER_BARRETT', 1);
/**
* @see Math_BigInteger::_mod2()
*/
define('MATH_BIGINTEGER_POWEROF2', 2);
/**
* @see Math_BigInteger::_remainder()
*/
define('MATH_BIGINTEGER_CLASSIC', 3);
/**
* @see Math_BigInteger::__clone()
*/
define('MATH_BIGINTEGER_NONE', 4);
/**#@-*/
/**#@+
* @access private
* @see Math_BigInteger::_montgomery()
* @see Math_BigInteger::_barrett()
*/
/**
* $cache[MATH_BIGINTEGER_VARIABLE] tells us whether or not the cached data is still valid.
*/
define('MATH_BIGINTEGER_VARIABLE', 0);
/**
* $cache[MATH_BIGINTEGER_DATA] contains the cached data.
*/
define('MATH_BIGINTEGER_DATA', 1);
/**#@-*/
/**#@+
* @access private
* @see Math_BigInteger::Math_BigInteger()
*/
/**
* To use the pure-PHP implementation
*/
define('MATH_BIGINTEGER_MODE_INTERNAL', 1);
/**
* To use the BCMath library
*
* (if enabled; otherwise, the internal implementation will be used)
*/
define('MATH_BIGINTEGER_MODE_BCMATH', 2);
/**
* To use the GMP library
*
* (if present; otherwise, either the BCMath or the internal implementation will be used)
*/
define('MATH_BIGINTEGER_MODE_GMP', 3);
/**#@-*/
/**
* The largest digit that may be used in addition / subtraction
*
* (we do pow(2, 52) instead of using 4503599627370496, directly, because some PHP installations
* will truncate 4503599627370496)
*
* @access private
*/
define('MATH_BIGINTEGER_MAX_DIGIT52', pow(2, 52));
/**
* Karatsuba Cutoff
*
* At what point do we switch between Karatsuba multiplication and schoolbook long multiplication?
*
* @access private
*/
define('MATH_BIGINTEGER_KARATSUBA_CUTOFF', 15);
/**
* Pure-PHP arbitrary precision integer arithmetic library. Supports base-2, base-10, base-16, and base-256
* numbers.
*
* @author Jim Wigginton <terrafrost@php.net>
* @version 1.0.0RC3
* @access public
* @package Math_BigInteger
*/
class Math_BigInteger {
/**
* Holds the BigInteger's value.
*
* @var Array
* @access private
*/
var $value;
/**
* Holds the BigInteger's magnitude.
*
* @var Boolean
* @access private
*/
var $is_negative = false;
/**
* Random number generator function
*
* @see setRandomGenerator()
* @access private
*/
var $generator = 'mt_rand';
/**
* Precision
*
* @see setPrecision()
* @access private
*/
var $precision = -1;
/**
* Precision Bitmask
*
* @see setPrecision()
* @access private
*/
var $bitmask = false;
/**
* Converts base-2, base-10, base-16, and binary strings (eg. base-256) to BigIntegers.
*
* If the second parameter - $base - is negative, then it will be assumed that the number's are encoded using
* two's compliment. The sole exception to this is -10, which is treated the same as 10 is.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('0x32', 16); // 50 in base-16
*
* echo $a->toString(); // outputs 50
* ?>
* </code>
*
* @param optional $x base-10 number or base-$base number if $base set.
* @param optional integer $base
* @return Math_BigInteger
* @access public
*/
function Math_BigInteger($x = 0, $base = 10)
{
if ( !defined('MATH_BIGINTEGER_MODE') ) {
switch (true) {
case extension_loaded('gmp'):
define('MATH_BIGINTEGER_MODE', MATH_BIGINTEGER_MODE_GMP);
break;
case extension_loaded('bcmath'):
define('MATH_BIGINTEGER_MODE', MATH_BIGINTEGER_MODE_BCMATH);
break;
default:
define('MATH_BIGINTEGER_MODE', MATH_BIGINTEGER_MODE_INTERNAL);
}
}
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
if (is_resource($x) && get_resource_type($x) == 'GMP integer') {
$this->value = $x;
return;
}
$this->value = gmp_init(0);
break;
case MATH_BIGINTEGER_MODE_BCMATH:
$this->value = '0';
break;
default:
$this->value = array();
}
if ($x === 0) {
return;
}
switch ($base) {
case -256:
if (ord($x[0]) & 0x80) {
$x = ~$x;
$this->is_negative = true;
}
case 256:
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$sign = $this->is_negative ? '-' : '';
$this->value = gmp_init($sign . '0x' . bin2hex($x));
break;
case MATH_BIGINTEGER_MODE_BCMATH:
// round $len to the nearest 4 (thanks, DavidMJ!)
$len = (strlen($x) + 3) & 0xFFFFFFFC;
$x = str_pad($x, $len, chr(0), STR_PAD_LEFT);
for ($i = 0; $i < $len; $i+= 4) {
$this->value = bcmul($this->value, '4294967296'); // 4294967296 == 2**32
$this->value = bcadd($this->value, 0x1000000 * ord($x[$i]) + ((ord($x[$i + 1]) << 16) | (ord($x[$i + 2]) << 8) | ord($x[$i + 3])));
}
if ($this->is_negative) {
$this->value = '-' . $this->value;
}
break;
// converts a base-2**8 (big endian / msb) number to base-2**26 (little endian / lsb)
default:
while (strlen($x)) {
$this->value[] = $this->_bytes2int($this->_base256_rshift($x, 26));
}
}
if ($this->is_negative) {
if (MATH_BIGINTEGER_MODE != MATH_BIGINTEGER_MODE_INTERNAL) {
$this->is_negative = false;
}
$temp = $this->add(new Math_BigInteger('-1'));
$this->value = $temp->value;
}
break;
case 16:
case -16:
if ($base > 0 && $x[0] == '-') {
$this->is_negative = true;
$x = substr($x, 1);
}
$x = preg_replace('#^(?:0x)?([A-Fa-f0-9]*).*#', '$1', $x);
$is_negative = false;
if ($base < 0 && hexdec($x[0]) >= 8) {
$this->is_negative = $is_negative = true;
$x = bin2hex(~pack('H*', $x));
}
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = $this->is_negative ? '-0x' . $x : '0x' . $x;
$this->value = gmp_init($temp);
$this->is_negative = false;
break;
case MATH_BIGINTEGER_MODE_BCMATH:
$x = ( strlen($x) & 1 ) ? '0' . $x : $x;
$temp = new Math_BigInteger(pack('H*', $x), 256);
$this->value = $this->is_negative ? '-' . $temp->value : $temp->value;
$this->is_negative = false;
break;
default:
$x = ( strlen($x) & 1 ) ? '0' . $x : $x;
$temp = new Math_BigInteger(pack('H*', $x), 256);
$this->value = $temp->value;
}
if ($is_negative) {
$temp = $this->add(new Math_BigInteger('-1'));
$this->value = $temp->value;
}
break;
case 10:
case -10:
$x = preg_replace('#^(-?[0-9]*).*#', '$1', $x);
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$this->value = gmp_init($x);
break;
case MATH_BIGINTEGER_MODE_BCMATH:
// explicitly casting $x to a string is necessary, here, since doing $x[0] on -1 yields different
// results then doing it on '-1' does (modInverse does $x[0])
$this->value = (string) $x;
break;
default:
$temp = new Math_BigInteger();
// array(10000000) is 10**7 in base-2**26. 10**7 is the closest to 2**26 we can get without passing it.
$multiplier = new Math_BigInteger();
$multiplier->value = array(10000000);
if ($x[0] == '-') {
$this->is_negative = true;
$x = substr($x, 1);
}
$x = str_pad($x, strlen($x) + (6 * strlen($x)) % 7, 0, STR_PAD_LEFT);
while (strlen($x)) {
$temp = $temp->multiply($multiplier);
$temp = $temp->add(new Math_BigInteger($this->_int2bytes(substr($x, 0, 7)), 256));
$x = substr($x, 7);
}
$this->value = $temp->value;
}
break;
case 2: // base-2 support originally implemented by Lluis Pamies - thanks!
case -2:
if ($base > 0 && $x[0] == '-') {
$this->is_negative = true;
$x = substr($x, 1);
}
$x = preg_replace('#^([01]*).*#', '$1', $x);
$x = str_pad($x, strlen($x) + (3 * strlen($x)) % 4, 0, STR_PAD_LEFT);
$str = '0x';
while (strlen($x)) {
$part = substr($x, 0, 4);
$str.= dechex(bindec($part));
$x = substr($x, 4);
}
if ($this->is_negative) {
$str = '-' . $str;
}
$temp = new Math_BigInteger($str, 8 * $base); // ie. either -16 or +16
$this->value = $temp->value;
$this->is_negative = $temp->is_negative;
break;
default:
// base not supported, so we'll let $this == 0
}
}
/**
* Converts a BigInteger to a byte string (eg. base-256).
*
* Negative numbers are saved as positive numbers, unless $twos_compliment is set to true, at which point, they're
* saved as two's compliment.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('65');
*
* echo $a->toBytes(); // outputs chr(65)
* ?>
* </code>
*
* @param Boolean $twos_compliment
* @return String
* @access public
* @internal Converts a base-2**26 number to base-2**8
*/
function toBytes($twos_compliment = false)
{
if ($twos_compliment) {
$comparison = $this->compare(new Math_BigInteger());
if ($comparison == 0) {
return $this->precision > 0 ? str_repeat(chr(0), ($this->precision + 1) >> 3) : '';
}
$temp = $comparison < 0 ? $this->add(new Math_BigInteger(1)) : $this->copy();
$bytes = $temp->toBytes();
if (empty($bytes)) { // eg. if the number we're trying to convert is -1
$bytes = chr(0);
}
if (ord($bytes[0]) & 0x80) {
$bytes = chr(0) . $bytes;
}
return $comparison < 0 ? ~$bytes : $bytes;
}
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
if (gmp_cmp($this->value, gmp_init(0)) == 0) {
return $this->precision > 0 ? str_repeat(chr(0), ($this->precision + 1) >> 3) : '';
}
$temp = gmp_strval(gmp_abs($this->value), 16);
$temp = ( strlen($temp) & 1 ) ? '0' . $temp : $temp;
$temp = pack('H*', $temp);
return $this->precision > 0 ?
substr(str_pad($temp, $this->precision >> 3, chr(0), STR_PAD_LEFT), -($this->precision >> 3)) :
ltrim($temp, chr(0));
case MATH_BIGINTEGER_MODE_BCMATH:
if ($this->value === '0') {
return $this->precision > 0 ? str_repeat(chr(0), ($this->precision + 1) >> 3) : '';
}
$value = '';
$current = $this->value;
if ($current[0] == '-') {
$current = substr($current, 1);
}
// we don't do four bytes at a time because then numbers larger than 1<<31 would be negative
// two's complimented numbers, which would break chr.
while (bccomp($current, '0') > 0) {
$temp = bcmod($current, 0x1000000);
$value = chr($temp >> 16) . chr($temp >> 8) . chr($temp) . $value;
$current = bcdiv($current, 0x1000000);
}
return $this->precision > 0 ?
substr(str_pad($value, $this->precision >> 3, chr(0), STR_PAD_LEFT), -($this->precision >> 3)) :
ltrim($value, chr(0));
}
if (!count($this->value)) {
return $this->precision > 0 ? str_repeat(chr(0), ($this->precision + 1) >> 3) : '';
}
$result = $this->_int2bytes($this->value[count($this->value) - 1]);
$temp = $this->copy();
for ($i = count($temp->value) - 2; $i >= 0; $i--) {
$temp->_base256_lshift($result, 26);
$result = $result | str_pad($temp->_int2bytes($temp->value[$i]), strlen($result), chr(0), STR_PAD_LEFT);
}
return $this->precision > 0 ?
substr(str_pad($result, $this->precision >> 3, chr(0), STR_PAD_LEFT), -($this->precision >> 3)) :
$result;
}
/**
* Converts a BigInteger to a hex string (eg. base-16)).
*
* Negative numbers are saved as positive numbers, unless $twos_compliment is set to true, at which point, they're
* saved as two's compliment.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('65');
*
* echo $a->toHex(); // outputs '41'
* ?>
* </code>
*
* @param Boolean $twos_compliment
* @return String
* @access public
* @internal Converts a base-2**26 number to base-2**8
*/
function toHex($twos_compliment = false)
{
return bin2hex($this->toBytes($twos_compliment));
}
/**
* Converts a BigInteger to a bit string (eg. base-2).
*
* Negative numbers are saved as positive numbers, unless $twos_compliment is set to true, at which point, they're
* saved as two's compliment.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('65');
*
* echo $a->toBits(); // outputs '1000001'
* ?>
* </code>
*
* @param Boolean $twos_compliment
* @return String
* @access public
* @internal Converts a base-2**26 number to base-2**2
*/
function toBits($twos_compliment = false)
{
$hex = $this->toHex($twos_compliment);
$bits = '';
for ($i = 0; $i < strlen($hex); $i+=8) {
$bits.= str_pad(decbin(hexdec(substr($hex, $i, 8))), 32, '0', STR_PAD_LEFT);
}
return $this->precision > 0 ? substr($bits, -$this->precision) : ltrim($bits, '0');
}
/**
* Converts a BigInteger to a base-10 number.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('50');
*
* echo $a->toString(); // outputs 50
* ?>
* </code>
*
* @return String
* @access public
* @internal Converts a base-2**26 number to base-10**7 (which is pretty much base-10)
*/
function toString()
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
return gmp_strval($this->value);
case MATH_BIGINTEGER_MODE_BCMATH:
if ($this->value === '0') {
return '0';
}
return ltrim($this->value, '0');
}
if (!count($this->value)) {
return '0';
}
$temp = $this->copy();
$temp->is_negative = false;
$divisor = new Math_BigInteger();
$divisor->value = array(10000000); // eg. 10**7
$result = '';
while (count($temp->value)) {
list($temp, $mod) = $temp->divide($divisor);
$result = str_pad($mod->value[0], 7, '0', STR_PAD_LEFT) . $result;
}
$result = ltrim($result, '0');
if ($this->is_negative) {
$result = '-' . $result;
}
return $result;
}
/**
* Copy an object
*
* PHP5 passes objects by reference while PHP4 passes by value. As such, we need a function to guarantee
* that all objects are passed by value, when appropriate. More information can be found here:
*
* {@link http://php.net/language.oop5.basic#51624}
*
* @access public
* @see __clone()
* @return Math_BigInteger
*/
function copy()
{
$temp = new Math_BigInteger();
$temp->value = $this->value;
$temp->is_negative = $this->is_negative;
$temp->generator = $this->generator;
$temp->precision = $this->precision;
$temp->bitmask = $this->bitmask;
return $temp;
}
/**
* __toString() magic method
*
* Will be called, automatically, if you're supporting just PHP5. If you're supporting PHP4, you'll need to call
* toString().
*
* @access public
* @internal Implemented per a suggestion by Techie-Michael - thanks!
*/
function __toString()
{
return $this->toString();
}
/**
* __clone() magic method
*
* Although you can call Math_BigInteger::__toString() directly in PHP5, you cannot call Math_BigInteger::__clone()
* directly in PHP5. You can in PHP4 since it's not a magic method, but in PHP5, you have to call it by using the PHP5
* only syntax of $y = clone $x. As such, if you're trying to write an application that works on both PHP4 and PHP5,
* call Math_BigInteger::copy(), instead.
*
* @access public
* @see copy()
* @return Math_BigInteger
*/
function __clone()
{
return $this->copy();
}
/**
* Adds two BigIntegers.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('10');
* $b = new Math_BigInteger('20');
*
* $c = $a->add($b);
*
* echo $c->toString(); // outputs 30
* ?>
* </code>
*
* @param Math_BigInteger $y
* @return Math_BigInteger
* @access public
* @internal Performs base-2**52 addition
*/
function add($y)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = new Math_BigInteger();
$temp->value = gmp_add($this->value, $y->value);
return $this->_normalize($temp);
case MATH_BIGINTEGER_MODE_BCMATH:
$temp = new Math_BigInteger();
$temp->value = bcadd($this->value, $y->value);
return $this->_normalize($temp);
}
$this_size = count($this->value);
$y_size = count($y->value);
if ($this_size == 0) {
return $y->copy();
} else if ($y_size == 0) {
return $this->copy();
}
// subtract, if appropriate
if ( $this->is_negative != $y->is_negative ) {
// is $y the negative number?
$y_negative = $this->compare($y) > 0;
$temp = $this->copy();
$y = $y->copy();
$temp->is_negative = $y->is_negative = false;
$diff = $temp->compare($y);
if ( !$diff ) {
$temp = new Math_BigInteger();
return $this->_normalize($temp);
}
$temp = $temp->subtract($y);
$temp->is_negative = ($diff > 0) ? !$y_negative : $y_negative;
return $this->_normalize($temp);
}
$result = new Math_BigInteger();
$carry = 0;
$size = max($this_size, $y_size);
$size+= $size & 1; // rounds $size to the nearest 2.
$x = array_pad($this->value, $size, 0);
$y = array_pad($y->value, $size, 0);
for ($i = 0; $i < $size - 1; $i+=2) {
$sum = $x[$i + 1] * 0x4000000 + $x[$i] + $y[$i + 1] * 0x4000000 + $y[$i] + $carry;
$carry = $sum >= MATH_BIGINTEGER_MAX_DIGIT52; // eg. floor($sum / 2**52); only possible values (in any base) are 0 and 1
$sum = $carry ? $sum - MATH_BIGINTEGER_MAX_DIGIT52 : $sum;
$temp = floor($sum / 0x4000000);
$result->value[] = $sum - 0x4000000 * $temp; // eg. a faster alternative to fmod($sum, 0x4000000)
$result->value[] = $temp;
}
if ($carry) {
$result->value[] = (int) $carry;
}
$result->is_negative = $this->is_negative;
return $this->_normalize($result);
}
/**
* Subtracts two BigIntegers.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('10');
* $b = new Math_BigInteger('20');
*
* $c = $a->subtract($b);
*
* echo $c->toString(); // outputs -10
* ?>
* </code>
*
* @param Math_BigInteger $y
* @return Math_BigInteger
* @access public
* @internal Performs base-2**52 subtraction
*/
function subtract($y)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = new Math_BigInteger();
$temp->value = gmp_sub($this->value, $y->value);
return $this->_normalize($temp);
case MATH_BIGINTEGER_MODE_BCMATH:
$temp = new Math_BigInteger();
$temp->value = bcsub($this->value, $y->value);
return $this->_normalize($temp);
}
$this_size = count($this->value);
$y_size = count($y->value);
if ($this_size == 0) {
$temp = $y->copy();
$temp->is_negative = !$temp->is_negative;
return $temp;
} else if ($y_size == 0) {
return $this->copy();
}
// add, if appropriate (ie. -$x - +$y or +$x - -$y)
if ( $this->is_negative != $y->is_negative ) {
$is_negative = $y->compare($this) > 0;
$temp = $this->copy();
$y = $y->copy();
$temp->is_negative = $y->is_negative = false;
$temp = $temp->add($y);
$temp->is_negative = $is_negative;
return $this->_normalize($temp);
}
$diff = $this->compare($y);
if ( !$diff ) {
$temp = new Math_BigInteger();
return $this->_normalize($temp);
}
// switch $this and $y around, if appropriate.
if ( (!$this->is_negative && $diff < 0) || ($this->is_negative && $diff > 0) ) {
$is_negative = $y->is_negative;
$temp = $this->copy();
$y = $y->copy();
$temp->is_negative = $y->is_negative = false;
$temp = $y->subtract($temp);
$temp->is_negative = !$is_negative;
return $this->_normalize($temp);
}
$result = new Math_BigInteger();
$carry = 0;
$size = max($this_size, $y_size);
$size+= $size % 2;
$x = array_pad($this->value, $size, 0);
$y = array_pad($y->value, $size, 0);
for ($i = 0; $i < $size - 1; $i+=2) {
$sum = $x[$i + 1] * 0x4000000 + $x[$i] - $y[$i + 1] * 0x4000000 - $y[$i] + $carry;
$carry = $sum < 0 ? -1 : 0; // eg. floor($sum / 2**52); only possible values (in any base) are 0 and 1
$sum = $carry ? $sum + MATH_BIGINTEGER_MAX_DIGIT52 : $sum;
$temp = floor($sum / 0x4000000);
$result->value[] = $sum - 0x4000000 * $temp;
$result->value[] = $temp;
}
// $carry shouldn't be anything other than zero, at this point, since we already made sure that $this
// was bigger than $y.
$result->is_negative = $this->is_negative;
return $this->_normalize($result);
}
/**
* Multiplies two BigIntegers
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('10');
* $b = new Math_BigInteger('20');
*
* $c = $a->multiply($b);
*
* echo $c->toString(); // outputs 200
* ?>
* </code>
*
* @param Math_BigInteger $x
* @return Math_BigInteger
* @access public
*/
function multiply($x)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = new Math_BigInteger();
$temp->value = gmp_mul($this->value, $x->value);
return $this->_normalize($temp);
case MATH_BIGINTEGER_MODE_BCMATH:
$temp = new Math_BigInteger();
$temp->value = bcmul($this->value, $x->value);
return $this->_normalize($temp);
}
static $cutoff = false;
if ($cutoff === false) {
$cutoff = 2 * MATH_BIGINTEGER_KARATSUBA_CUTOFF;
}
if ( $this->equals($x) ) {
return $this->_square();
}
$this_length = count($this->value);
$x_length = count($x->value);
if ( !$this_length || !$x_length ) { // a 0 is being multiplied
$temp = new Math_BigInteger();
return $this->_normalize($temp);
}
$product = min($this_length, $x_length) < $cutoff ? $this->_multiply($x) : $this->_karatsuba($x);
$product->is_negative = $this->is_negative != $x->is_negative;
return $this->_normalize($product);
}
/**
* Performs long multiplication up to $stop digits
*
* If you're going to be doing array_slice($product->value, 0, $stop), some cycles can be saved.
*
* @see _barrett()
* @param Math_BigInteger $x
* @return Math_BigInteger
* @access private
*/
function _multiplyLower($x, $stop)
{
$this_length = count($this->value);
$x_length = count($x->value);
if ( !$this_length || !$x_length ) { // a 0 is being multiplied
return new Math_BigInteger();
}
if ( $this_length < $x_length ) {
return $x->_multiplyLower($this, $stop);
}
$product = new Math_BigInteger();
$product->value = $this->_array_repeat(0, $this_length + $x_length);
// the following for loop could be removed if the for loop following it
// (the one with nested for loops) initially set $i to 0, but
// doing so would also make the result in one set of unnecessary adds,
// since on the outermost loops first pass, $product->value[$k] is going
// to always be 0
$carry = 0;
for ($j = 0; $j < $this_length; $j++) { // ie. $i = 0, $k = $i
$temp = $this->value[$j] * $x->value[0] + $carry; // $product->value[$k] == 0
$carry = floor($temp / 0x4000000);
$product->value[$j] = $temp - 0x4000000 * $carry;
}
if ($j < $stop) {
$product->value[$j] = $carry;
}
// the above for loop is what the previous comment was talking about. the
// following for loop is the "one with nested for loops"
for ($i = 1; $i < $x_length; $i++) {
$carry = 0;
for ($j = 0, $k = $i; $j < $this_length && $k < $stop; $j++, $k++) {
$temp = $product->value[$k] + $this->value[$j] * $x->value[$i] + $carry;
$carry = floor($temp / 0x4000000);
$product->value[$k] = $temp - 0x4000000 * $carry;
}
if ($k < $stop) {
$product->value[$k] = $carry;
}
}
$product->is_negative = $this->is_negative != $x->is_negative;
return $product;
}
/**
* Performs long multiplication on two BigIntegers
*
* Modeled after 'multiply' in MutableBigInteger.java.
*
* @param Math_BigInteger $x
* @return Math_BigInteger
* @access private
*/
function _multiply($x)
{
$this_length = count($this->value);
$x_length = count($x->value);
if ( !$this_length || !$x_length ) { // a 0 is being multiplied
return new Math_BigInteger();
}
if ( $this_length < $x_length ) {
return $x->_multiply($this);
}
$product = new Math_BigInteger();
$product->value = $this->_array_repeat(0, $this_length + $x_length);
// the following for loop could be removed if the for loop following it
// (the one with nested for loops) initially set $i to 0, but
// doing so would also make the result in one set of unnecessary adds,
// since on the outermost loops first pass, $product->value[$k] is going
// to always be 0
$carry = 0;
for ($j = 0; $j < $this_length; $j++) { // ie. $i = 0
$temp = $this->value[$j] * $x->value[0] + $carry; // $product->value[$k] == 0
$carry = floor($temp / 0x4000000);
$product->value[$j] = $temp - 0x4000000 * $carry;
}
$product->value[$j] = $carry;
// the above for loop is what the previous comment was talking about. the
// following for loop is the "one with nested for loops"
for ($i = 1; $i < $x_length; $i++) {
$carry = 0;
for ($j = 0, $k = $i; $j < $this_length; $j++, $k++) {
$temp = $product->value[$k] + $this->value[$j] * $x->value[$i] + $carry;
$carry = floor($temp / 0x4000000);
$product->value[$k] = $temp - 0x4000000 * $carry;
}
$product->value[$k] = $carry;
}
$product->is_negative = $this->is_negative != $x->is_negative;
return $this->_normalize($product);
}
/**
* Performs Karatsuba multiplication on two BigIntegers
*
* See {@link http://en.wikipedia.org/wiki/Karatsuba_algorithm Karatsuba algorithm} and
* {@link http://math.libtomcrypt.com/files/tommath.pdf#page=120 MPM 5.2.3}.
*
* @param Math_BigInteger $y
* @return Math_BigInteger
* @access private
*/
function _karatsuba($y)
{
$x = $this->copy();
$m = min(count($x->value) >> 1, count($y->value) >> 1);
if ($m < MATH_BIGINTEGER_KARATSUBA_CUTOFF) {
return $x->_multiply($y);
}
$x1 = new Math_BigInteger();
$x0 = new Math_BigInteger();
$y1 = new Math_BigInteger();
$y0 = new Math_BigInteger();
$x1->value = array_slice($x->value, $m);
$x0->value = array_slice($x->value, 0, $m);
$y1->value = array_slice($y->value, $m);
$y0->value = array_slice($y->value, 0, $m);
$z2 = $x1->_karatsuba($y1);
$z0 = $x0->_karatsuba($y0);
$z1 = $x1->add($x0);
$z1 = $z1->_karatsuba($y1->add($y0));
$z1 = $z1->subtract($z2->add($z0));
$z2->value = array_merge(array_fill(0, 2 * $m, 0), $z2->value);
$z1->value = array_merge(array_fill(0, $m, 0), $z1->value);
$xy = $z2->add($z1);
$xy = $xy->add($z0);
return $xy;
}
/**
* Squares a BigInteger
*
* @return Math_BigInteger
* @access private
*/
function _square()
{
static $cutoff = false;
if ($cutoff === false) {
$cutoff = 2 * MATH_BIGINTEGER_KARATSUBA_CUTOFF;
}
return count($this->value) < $cutoff ? $this->_baseSquare() : $this->_karatsubaSquare();
}
/**
* Performs traditional squaring on two BigIntegers
*
* Squaring can be done faster than multiplying a number by itself can be. See
* {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf#page=7 HAC 14.2.4} /
* {@link http://math.libtomcrypt.com/files/tommath.pdf#page=141 MPM 5.3} for more information.
*
* @return Math_BigInteger
* @access private
*/
function _baseSquare()
{
if ( empty($this->value) ) {
return new Math_BigInteger();
}
$square = new Math_BigInteger();
$square->value = $this->_array_repeat(0, 2 * count($this->value));
for ($i = 0, $max_index = count($this->value) - 1; $i <= $max_index; $i++) {
$i2 = 2 * $i;
$temp = $square->value[$i2] + $this->value[$i] * $this->value[$i];
$carry = floor($temp / 0x4000000);
$square->value[$i2] = $temp - 0x4000000 * $carry;
// note how we start from $i+1 instead of 0 as we do in multiplication.
for ($j = $i + 1, $k = $i2 + 1; $j <= $max_index; $j++, $k++) {
$temp = $square->value[$k] + 2 * $this->value[$j] * $this->value[$i] + $carry;
$carry = floor($temp / 0x4000000);
$square->value[$k] = $temp - 0x4000000 * $carry;
}
// the following line can yield values larger 2**15. at this point, PHP should switch
// over to floats.
$square->value[$i + $max_index + 1] = $carry;
}
return $square;
}
/**
* Performs Karatsuba "squaring" on two BigIntegers
*
* See {@link http://en.wikipedia.org/wiki/Karatsuba_algorithm Karatsuba algorithm} and
* {@link http://math.libtomcrypt.com/files/tommath.pdf#page=151 MPM 5.3.4}.
*
* @param Math_BigInteger $y
* @return Math_BigInteger
* @access private
*/
function _karatsubaSquare()
{
$m = count($this->value) >> 1;
if ($m < MATH_BIGINTEGER_KARATSUBA_CUTOFF) {
return $this->_square();
}
$x1 = new Math_BigInteger();
$x0 = new Math_BigInteger();
$x1->value = array_slice($this->value, $m);
$x0->value = array_slice($this->value, 0, $m);
$z2 = $x1->_karatsubaSquare();
$z0 = $x0->_karatsubaSquare();
$z1 = $x1->add($x0);
$z1 = $z1->_karatsubaSquare();
$z1 = $z1->subtract($z2->add($z0));
$z2->value = array_merge(array_fill(0, 2 * $m, 0), $z2->value);
$z1->value = array_merge(array_fill(0, $m, 0), $z1->value);
$xx = $z2->add($z1);
$xx = $xx->add($z0);
return $xx;
}
/**
* Divides two BigIntegers.
*
* Returns an array whose first element contains the quotient and whose second element contains the
* "common residue". If the remainder would be positive, the "common residue" and the remainder are the
* same. If the remainder would be negative, the "common residue" is equal to the sum of the remainder
* and the divisor (basically, the "common residue" is the first positive modulo).
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('10');
* $b = new Math_BigInteger('20');
*
* list($quotient, $remainder) = $a->divide($b);
*
* echo $quotient->toString(); // outputs 0
* echo "\r\n";
* echo $remainder->toString(); // outputs 10
* ?>
* </code>
*
* @param Math_BigInteger $y
* @return Array
* @access public
* @internal This function is based off of {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf#page=9 HAC 14.20}.
*/
function divide($y)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$quotient = new Math_BigInteger();
$remainder = new Math_BigInteger();
list($quotient->value, $remainder->value) = gmp_div_qr($this->value, $y->value);
if (gmp_sign($remainder->value) < 0) {
$remainder->value = gmp_add($remainder->value, gmp_abs($y->value));
}
return array($this->_normalize($quotient), $this->_normalize($remainder));
case MATH_BIGINTEGER_MODE_BCMATH:
$quotient = new Math_BigInteger();
$remainder = new Math_BigInteger();
$quotient->value = bcdiv($this->value, $y->value);
$remainder->value = bcmod($this->value, $y->value);
if ($remainder->value[0] == '-') {
$remainder->value = bcadd($remainder->value, $y->value[0] == '-' ? substr($y->value, 1) : $y->value);
}
return array($this->_normalize($quotient), $this->_normalize($remainder));
}
if (count($y->value) == 1) {
$temp = $this->_divide_digit($y->value[0]);
$temp[0]->is_negative = $this->is_negative != $y->is_negative;
return array($this->_normalize($temp[0]), $this->_normalize($temp[1]));
}
static $zero;
if (!isset($zero)) {
$zero = new Math_BigInteger();
}
$x = $this->copy();
$y = $y->copy();
$x_sign = $x->is_negative;
$y_sign = $y->is_negative;
$x->is_negative = $y->is_negative = false;
$diff = $x->compare($y);
if ( !$diff ) {
$temp = new Math_BigInteger();
$temp->value = array(1);
$temp->is_negative = $x_sign != $y_sign;
return array($this->_normalize($temp), $this->_normalize(new Math_BigInteger()));
}
if ( $diff < 0 ) {
// if $x is negative, "add" $y.
if ( $x_sign ) {
$x = $y->subtract($x);
}
return array($this->_normalize(new Math_BigInteger()), $this->_normalize($x));
}
// normalize $x and $y as described in HAC 14.23 / 14.24
$msb = $y->value[count($y->value) - 1];
for ($shift = 0; !($msb & 0x2000000); $shift++) {
$msb <<= 1;
}
$x->_lshift($shift);
$y->_lshift($shift);
$x_max = count($x->value) - 1;
$y_max = count($y->value) - 1;
$quotient = new Math_BigInteger();
$quotient->value = $this->_array_repeat(0, $x_max - $y_max + 1);
// $temp = $y << ($x_max - $y_max-1) in base 2**26
$temp = new Math_BigInteger();
$temp->value = array_merge($this->_array_repeat(0, $x_max - $y_max), $y->value);
while ( $x->compare($temp) >= 0 ) {
// calculate the "common residue"
$quotient->value[$x_max - $y_max]++;
$x = $x->subtract($temp);
$x_max = count($x->value) - 1;
}
for ($i = $x_max; $i >= $y_max + 1; $i--) {
$x_value = array(
$x->value[$i],
( $i > 0 ) ? $x->value[$i - 1] : 0,
( $i > 1 ) ? $x->value[$i - 2] : 0
);
$y_value = array(
$y->value[$y_max],
( $y_max > 0 ) ? $y->value[$y_max - 1] : 0
);
$q_index = $i - $y_max - 1;
if ($x_value[0] == $y_value[0]) {
$quotient->value[$q_index] = 0x3FFFFFF;
} else {
$quotient->value[$q_index] = floor(
($x_value[0] * 0x4000000 + $x_value[1])
/
$y_value[0]
);
}
$temp = new Math_BigInteger();
$temp->value = array($y_value[1], $y_value[0]);
$lhs = new Math_BigInteger();
$lhs->value = array($quotient->value[$q_index]);
$lhs = $lhs->multiply($temp);
$rhs = new Math_BigInteger();
$rhs->value = array($x_value[2], $x_value[1], $x_value[0]);
while ( $lhs->compare($rhs) > 0 ) {
$quotient->value[$q_index]--;
$lhs = new Math_BigInteger();
$lhs->value = array($quotient->value[$q_index]);
$lhs = $lhs->multiply($temp);
}
$adjust = $this->_array_repeat(0, $q_index);
$temp = new Math_BigInteger();
$temp->value = array($quotient->value[$q_index]);
$temp = $temp->multiply($y);
$temp->value = array_merge($adjust, $temp->value);
$x = $x->subtract($temp);
if ($x->compare($zero) < 0) {
$temp->value = array_merge($adjust, $y->value);
$x = $x->add($temp);
$quotient->value[$q_index]--;
}
$x_max = count($x->value) - 1;
}
// unnormalize the remainder
$x->_rshift($shift);
$quotient->is_negative = $x_sign != $y_sign;
// calculate the "common residue", if appropriate
if ( $x_sign ) {
$y->_rshift($shift);
$x = $y->subtract($x);
}
return array($this->_normalize($quotient), $this->_normalize($x));
}
/**
* Divides a BigInteger by a regular integer
*
* abc / x = a00 / x + b0 / x + c / x
*
* @param Math_BigInteger $divisor
* @return Array
* @access public
*/
function _divide_digit($divisor)
{
$carry = 0;
$result = new Math_BigInteger();
for ($i = count($this->value) - 1; $i >= 0; $i--) {
$temp = 0x4000000 * $carry + $this->value[$i];
$result->value[$i] = floor($temp / $divisor);
$carry = fmod($temp, $divisor);
}
$remainder = new Math_BigInteger();
$remainder->value = array($carry);
return array($result, $remainder);
}
/**
* Performs modular exponentiation.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger('10');
* $b = new Math_BigInteger('20');
* $c = new Math_BigInteger('30');
*
* $c = $a->modPow($b, $c);
*
* echo $c->toString(); // outputs 10
* ?>
* </code>
*
* @param Math_BigInteger $e
* @param Math_BigInteger $n
* @return Math_BigInteger
* @access public
* @internal The most naive approach to modular exponentiation has very unreasonable requirements, and
* and although the approach involving repeated squaring does vastly better, it, too, is impractical
* for our purposes. The reason being that division - by far the most complicated and time-consuming
* of the basic operations (eg. +,-,*,/) - occurs multiple times within it.
*
* Modular reductions resolve this issue. Although an individual modular reduction takes more time
* then an individual division, when performed in succession (with the same modulo), they're a lot faster.
*
* The two most commonly used modular reductions are Barrett and Montgomery reduction. Montgomery reduction,
* although faster, only works when the gcd of the modulo and of the base being used is 1. In RSA, when the
* base is a power of two, the modulo - a product of two primes - is always going to have a gcd of 1 (because
* the product of two odd numbers is odd), but what about when RSA isn't used?
*
* In contrast, Barrett reduction has no such constraint. As such, some bigint implementations perform a
* Barrett reduction after every operation in the modpow function. Others perform Barrett reductions when the
* modulo is even and Montgomery reductions when the modulo is odd. BigInteger.java's modPow method, however,
* uses a trick involving the Chinese Remainder Theorem to factor the even modulo into two numbers - one odd and
* the other, a power of two - and recombine them, later. This is the method that this modPow function uses.
* {@link http://islab.oregonstate.edu/papers/j34monex.pdf Montgomery Reduction with Even Modulus} elaborates.
*/
function modPow($e, $n)
{
$n = $this->bitmask !== false && $this->bitmask->compare($n) < 0 ? $this->bitmask : $n->abs();
if ($e->compare(new Math_BigInteger()) < 0) {
$e = $e->abs();
$temp = $this->modInverse($n);
if ($temp === false) {
return false;
}
return $this->_normalize($temp->modPow($e, $n));
}
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = new Math_BigInteger();
$temp->value = gmp_powm($this->value, $e->value, $n->value);
return $this->_normalize($temp);
case MATH_BIGINTEGER_MODE_BCMATH:
$temp = new Math_BigInteger();
$temp->value = bcpowmod($this->value, $e->value, $n->value);
return $this->_normalize($temp);
}
if ( empty($e->value) ) {
$temp = new Math_BigInteger();
$temp->value = array(1);
return $this->_normalize($temp);
}
if ( $e->value == array(1) ) {
list(, $temp) = $this->divide($n);
return $this->_normalize($temp);
}
if ( $e->value == array(2) ) {
$temp = $this->_square();
list(, $temp) = $temp->divide($n);
return $this->_normalize($temp);
}
return $this->_normalize($this->_slidingWindow($e, $n, MATH_BIGINTEGER_BARRETT));
// is the modulo odd?
if ( $n->value[0] & 1 ) {
return $this->_normalize($this->_slidingWindow($e, $n, MATH_BIGINTEGER_MONTGOMERY));
}
// if it's not, it's even
// find the lowest set bit (eg. the max pow of 2 that divides $n)
for ($i = 0; $i < count($n->value); $i++) {
if ( $n->value[$i] ) {
$temp = decbin($n->value[$i]);
$j = strlen($temp) - strrpos($temp, '1') - 1;
$j+= 26 * $i;
break;
}
}
// at this point, 2^$j * $n/(2^$j) == $n
$mod1 = $n->copy();
$mod1->_rshift($j);
$mod2 = new Math_BigInteger();
$mod2->value = array(1);
$mod2->_lshift($j);
$part1 = ( $mod1->value != array(1) ) ? $this->_slidingWindow($e, $mod1, MATH_BIGINTEGER_MONTGOMERY) : new Math_BigInteger();
$part2 = $this->_slidingWindow($e, $mod2, MATH_BIGINTEGER_POWEROF2);
$y1 = $mod2->modInverse($mod1);
$y2 = $mod1->modInverse($mod2);
$result = $part1->multiply($mod2);
$result = $result->multiply($y1);
$temp = $part2->multiply($mod1);
$temp = $temp->multiply($y2);
$result = $result->add($temp);
list(, $result) = $result->divide($n);
return $this->_normalize($result);
}
/**
* Performs modular exponentiation.
*
* Alias for Math_BigInteger::modPow()
*
* @param Math_BigInteger $e
* @param Math_BigInteger $n
* @return Math_BigInteger
* @access public
*/
function powMod($e, $n)
{
return $this->modPow($e, $n);
}
/**
* Sliding Window k-ary Modular Exponentiation
*
* Based on {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf#page=27 HAC 14.85} /
* {@link http://math.libtomcrypt.com/files/tommath.pdf#page=210 MPM 7.7}. In a departure from those algorithims,
* however, this function performs a modular reduction after every multiplication and squaring operation.
* As such, this function has the same preconditions that the reductions being used do.
*
* @param Math_BigInteger $e
* @param Math_BigInteger $n
* @param Integer $mode
* @return Math_BigInteger
* @access private
*/
function _slidingWindow($e, $n, $mode)
{
static $window_ranges = array(7, 25, 81, 241, 673, 1793); // from BigInteger.java's oddModPow function
//static $window_ranges = array(0, 7, 36, 140, 450, 1303, 3529); // from MPM 7.3.1
$e_length = count($e->value) - 1;
$e_bits = decbin($e->value[$e_length]);
for ($i = $e_length - 1; $i >= 0; $i--) {
$e_bits.= str_pad(decbin($e->value[$i]), 26, '0', STR_PAD_LEFT);
}
$e_length = strlen($e_bits);
// calculate the appropriate window size.
// $window_size == 3 if $window_ranges is between 25 and 81, for example.
for ($i = 0, $window_size = 1; $e_length > $window_ranges[$i] && $i < count($window_ranges); $window_size++, $i++);
switch ($mode) {
case MATH_BIGINTEGER_MONTGOMERY:
$reduce = '_montgomery';
$prep = '_prepMontgomery';
break;
case MATH_BIGINTEGER_BARRETT:
$reduce = '_barrett';
$prep = '_barrett';
break;
case MATH_BIGINTEGER_POWEROF2:
$reduce = '_mod2';
$prep = '_mod2';
break;
case MATH_BIGINTEGER_CLASSIC:
$reduce = '_remainder';
$prep = '_remainder';
break;
case MATH_BIGINTEGER_NONE:
// ie. do no modular reduction. useful if you want to just do pow as opposed to modPow.
$reduce = 'copy';
$prep = 'copy';
break;
default:
// an invalid $mode was provided
}
// precompute $this^0 through $this^$window_size
$powers = array();
$powers[1] = $this->$prep($n);
$powers[2] = $powers[1]->_square();
$powers[2] = $powers[2]->$reduce($n);
// we do every other number since substr($e_bits, $i, $j+1) (see below) is supposed to end
// in a 1. ie. it's supposed to be odd.
$temp = 1 << ($window_size - 1);
for ($i = 1; $i < $temp; $i++) {
$powers[2 * $i + 1] = $powers[2 * $i - 1]->multiply($powers[2]);
$powers[2 * $i + 1] = $powers[2 * $i + 1]->$reduce($n);
}
$result = new Math_BigInteger();
$result->value = array(1);
$result = $result->$prep($n);
for ($i = 0; $i < $e_length; ) {
if ( !$e_bits[$i] ) {
$result = $result->_square();
$result = $result->$reduce($n);
$i++;
} else {
for ($j = $window_size - 1; $j > 0; $j--) {
if ( !empty($e_bits[$i + $j]) ) {
break;
}
}
for ($k = 0; $k <= $j; $k++) {// eg. the length of substr($e_bits, $i, $j+1)
$result = $result->_square();
$result = $result->$reduce($n);
}
$result = $result->multiply($powers[bindec(substr($e_bits, $i, $j + 1))]);
$result = $result->$reduce($n);
$i+=$j + 1;
}
}
$result = $result->$reduce($n);
return $result;
}
/**
* Remainder
*
* A wrapper for the divide function.
*
* @see divide()
* @see _slidingWindow()
* @access private
* @param Math_BigInteger
* @return Math_BigInteger
*/
function _remainder($n)
{
list(, $temp) = $this->divide($n);
return $temp;
}
/**
* Modulos for Powers of Two
*
* Calculates $x%$n, where $n = 2**$e, for some $e. Since this is basically the same as doing $x & ($n-1),
* we'll just use this function as a wrapper for doing that.
*
* @see _slidingWindow()
* @access private
* @param Math_BigInteger
* @return Math_BigInteger
*/
function _mod2($n)
{
$temp = new Math_BigInteger();
$temp->value = array(1);
return $this->bitwise_and($n->subtract($temp));
}
/**
* Barrett Modular Reduction
*
* See {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf#page=14 HAC 14.3.3} /
* {@link http://math.libtomcrypt.com/files/tommath.pdf#page=165 MPM 6.2.5} for more information. Modified slightly,
* so as not to require negative numbers (initially, this script didn't support negative numbers).
*
* @see _slidingWindow()
* @access private
* @param Math_BigInteger
* @return Math_BigInteger
*/
function _barrett($n)
{
static $cache = array(
MATH_BIGINTEGER_VARIABLE => array(),
MATH_BIGINTEGER_DATA => array()
);
$n_length = count($n->value);
if (count($this->value) > 2 * $n_length) {
list(, $temp) = $this->divide($n);
return $temp;
}
if ( ($key = array_search($n->value, $cache[MATH_BIGINTEGER_VARIABLE])) === false ) {
$key = count($cache[MATH_BIGINTEGER_VARIABLE]);
$cache[MATH_BIGINTEGER_VARIABLE][] = $n->value;
$temp = new Math_BigInteger();
$temp->value = $this->_array_repeat(0, 2 * $n_length);
$temp->value[] = 1;
list($cache[MATH_BIGINTEGER_DATA][], ) = $temp->divide($n);
}
$temp = new Math_BigInteger();
$temp->value = array_slice($this->value, $n_length - 1);
$temp = $temp->multiply($cache[MATH_BIGINTEGER_DATA][$key]);
$temp->value = array_slice($temp->value, $n_length + 1);
$result = new Math_BigInteger();
$result->value = array_slice($this->value, 0, $n_length + 1);
$temp = $temp->_multiplyLower($n, $n_length + 1);
// $temp->value == array_slice($temp->multiply($n)->value, 0, $n_length + 1)
if ($result->compare($temp) < 0) {
$corrector = new Math_BigInteger();
$corrector->value = $this->_array_repeat(0, $n_length + 1);
$corrector->value[] = 1;
$result = $result->add($corrector);
}
$result = $result->subtract($temp);
while ($result->compare($n) > 0) {
$result = $result->subtract($n);
}
return $result;
}
/**
* Montgomery Modular Reduction
*
* ($this->_prepMontgomery($n))->_montgomery($n) yields $x%$n.
* {@link http://math.libtomcrypt.com/files/tommath.pdf#page=170 MPM 6.3} provides insights on how this can be
* improved upon (basically, by using the comba method). gcd($n, 2) must be equal to one for this function
* to work correctly.
*
* @see _prepMontgomery()
* @see _slidingWindow()
* @access private
* @param Math_BigInteger
* @return Math_BigInteger
*/
function _montgomery($n)
{
static $cache = array(
MATH_BIGINTEGER_VARIABLE => array(),
MATH_BIGINTEGER_DATA => array()
);
if ( ($key = array_search($n->value, $cache[MATH_BIGINTEGER_VARIABLE])) === false ) {
$key = count($cache[MATH_BIGINTEGER_VARIABLE]);
$cache[MATH_BIGINTEGER_VARIABLE][] = $n->value;
$cache[MATH_BIGINTEGER_DATA][] = $n->_modInverse67108864();
}
$k = count($n->value);
$result = $this->copy();
for ($i = 0; $i < $k; $i++) {
$temp = new Math_BigInteger();
$temp->value = array(
($result->value[$i] * $cache[MATH_BIGINTEGER_DATA][$key]) & 0x3FFFFFF
);
$temp = $temp->multiply($n);
$temp->value = array_merge($this->_array_repeat(0, $i), $temp->value);
$result = $result->add($temp);
}
$result->value = array_slice($result->value, $k);
if ($result->compare($n) >= 0) {
$result = $result->subtract($n);
}
return $result;
}
/**
* Prepare a number for use in Montgomery Modular Reductions
*
* @see _montgomery()
* @see _slidingWindow()
* @access private
* @param Math_BigInteger
* @return Math_BigInteger
*/
function _prepMontgomery($n)
{
$k = count($n->value);
$temp = new Math_BigInteger();
$temp->value = array_merge($this->_array_repeat(0, $k), $this->value);
list(, $temp) = $temp->divide($n);
return $temp;
}
/**
* Modular Inverse of a number mod 2**26 (eg. 67108864)
*
* Based off of the bnpInvDigit function implemented and justified in the following URL:
*
* {@link http://www-cs-students.stanford.edu/~tjw/jsbn/jsbn.js}
*
* The following URL provides more info:
*
* {@link http://groups.google.com/group/sci.crypt/msg/7a137205c1be7d85}
*
* As for why we do all the bitmasking... strange things can happen when converting from floats to ints. For
* instance, on some computers, var_dump((int) -4294967297) yields int(-1) and on others, it yields
* int(-2147483648). To avoid problems stemming from this, we use bitmasks to guarantee that ints aren't
* auto-converted to floats. The outermost bitmask is present because without it, there's no guarantee that
* the "residue" returned would be the so-called "common residue". We use fmod, in the last step, because the
* maximum possible $x is 26 bits and the maximum $result is 16 bits. Thus, we have to be able to handle up to
* 40 bits, which only 64-bit floating points will support.
*
* Thanks to Pedro Gimeno Fortea for input!
*
* @see _montgomery()
* @access private
* @return Integer
*/
function _modInverse67108864() // 2**26 == 67108864
{
$x = -$this->value[0];
$result = $x & 0x3; // x**-1 mod 2**2
$result = ($result * (2 - $x * $result)) & 0xF; // x**-1 mod 2**4
$result = ($result * (2 - ($x & 0xFF) * $result)) & 0xFF; // x**-1 mod 2**8
$result = ($result * ((2 - ($x & 0xFFFF) * $result) & 0xFFFF)) & 0xFFFF; // x**-1 mod 2**16
$result = fmod($result * (2 - fmod($x * $result, 0x4000000)), 0x4000000); // x**-1 mod 2**26
return $result & 0x3FFFFFF;
}
/**
* Calculates modular inverses.
*
* Say you have (30 mod 17 * x mod 17) mod 17 == 1. x can be found using modular inverses.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger(30);
* $b = new Math_BigInteger(17);
*
* $c = $a->modInverse($b);
* echo $c->toString(); // outputs 4
*
* echo "\r\n";
*
* $d = $a->multiply($c);
* list(, $d) = $d->divide($b);
* echo $d; // outputs 1 (as per the definition of modular inverse)
* ?>
* </code>
*
* @param Math_BigInteger $n
* @return mixed false, if no modular inverse exists, Math_BigInteger, otherwise.
* @access public
* @internal See {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf#page=21 HAC 14.64} for more information.
*/
function modInverse($n)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = new Math_BigInteger();
$temp->value = gmp_invert($this->value, $n->value);
return ( $temp->value === false ) ? false : $this->_normalize($temp);
}
static $zero, $one;
if (!isset($zero)) {
$zero = new Math_BigInteger();
$one = new Math_BigInteger(1);
}
// $x mod $n == $x mod -$n.
$n = $n->abs();
if ($this->compare($zero) < 0) {
$temp = $this->abs();
$temp = $temp->modInverse($n);
return $negated === false ? false : $this->_normalize($n->subtract($temp));
}
extract($this->extendedGCD($n));
if (!$gcd->equals($one)) {
return false;
}
$x = $x->compare($zero) < 0 ? $x->add($n) : $x;
return $this->compare($zero) < 0 ? $this->_normalize($n->subtract($x)) : $this->_normalize($x);
}
/**
* Calculates the greatest common divisor and B<EFBFBD>zout's identity.
*
* Say you have 693 and 609. The GCD is 21. B<EFBFBD>zout's identity states that there exist integers x and y such that
* 693*x + 609*y == 21. In point of fact, there are actually an infinite number of x and y combinations and which
* combination is returned is dependant upon which mode is in use. See
* {@link http://en.wikipedia.org/wiki/B%C3%A9zout%27s_identity B<EFBFBD>zout's identity - Wikipedia} for more information.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger(693);
* $b = new Math_BigInteger(609);
*
* extract($a->extendedGCD($b));
*
* echo $gcd->toString() . "\r\n"; // outputs 21
* echo $a->toString() * $x->toString() + $b->toString() * $y->toString(); // outputs 21
* ?>
* </code>
*
* @param Math_BigInteger $n
* @return Math_BigInteger
* @access public
* @internal Calculates the GCD using the binary xGCD algorithim described in
* {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap14.pdf#page=19 HAC 14.61}. As the text above 14.61 notes,
* the more traditional algorithim requires "relatively costly multiple-precision divisions".
*/
function extendedGCD($n) {
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
extract(gmp_gcdext($this->value, $n->value));
return array(
'gcd' => $this->_normalize(new Math_BigInteger($g)),
'x' => $this->_normalize(new Math_BigInteger($s)),
'y' => $this->_normalize(new Math_BigInteger($t))
);
case MATH_BIGINTEGER_MODE_BCMATH:
// it might be faster to use the binary xGCD algorithim here, as well, but (1) that algorithim works
// best when the base is a power of 2 and (2) i don't think it'd make much difference, anyway. as is,
// the basic extended euclidean algorithim is what we're using.
$u = $this->value;
$v = $n->value;
$a = '1';
$b = '0';
$c = '0';
$d = '1';
while (bccomp($v, '0') != 0) {
$q = bcdiv($u, $v);
$temp = $u;
$u = $v;
$v = bcsub($temp, bcmul($v, $q));
$temp = $a;
$a = $c;
$c = bcsub($temp, bcmul($a, $q));
$temp = $b;
$b = $d;
$d = bcsub($temp, bcmul($b, $q));
}
return array(
'gcd' => $this->_normalize(new Math_BigInteger($u)),
'x' => $this->_normalize(new Math_BigInteger($a)),
'y' => $this->_normalize(new Math_BigInteger($b))
);
}
$y = $n->copy();
$x = $this->copy();
$g = new Math_BigInteger();
$g->value = array(1);
while ( !(($x->value[0] & 1)|| ($y->value[0] & 1)) ) {
$x->_rshift(1);
$y->_rshift(1);
$g->_lshift(1);
}
$u = $x->copy();
$v = $y->copy();
$a = new Math_BigInteger();
$b = new Math_BigInteger();
$c = new Math_BigInteger();
$d = new Math_BigInteger();
$a->value = $d->value = $g->value = array(1);
while ( !empty($u->value) ) {
while ( !($u->value[0] & 1) ) {
$u->_rshift(1);
if ( ($a->value[0] & 1) || ($b->value[0] & 1) ) {
$a = $a->add($y);
$b = $b->subtract($x);
}
$a->_rshift(1);
$b->_rshift(1);
}
while ( !($v->value[0] & 1) ) {
$v->_rshift(1);
if ( ($c->value[0] & 1) || ($d->value[0] & 1) ) {
$c = $c->add($y);
$d = $d->subtract($x);
}
$c->_rshift(1);
$d->_rshift(1);
}
if ($u->compare($v) >= 0) {
$u = $u->subtract($v);
$a = $a->subtract($c);
$b = $b->subtract($d);
} else {
$v = $v->subtract($u);
$c = $c->subtract($a);
$d = $d->subtract($b);
}
}
return array(
'gcd' => $this->_normalize($g->multiply($v)),
'x' => $this->_normalize($c),
'y' => $this->_normalize($d)
);
}
/**
* Calculates the greatest common divisor
*
* Say you have 693 and 609. The GCD is 21.
*
* Here's an example:
* <code>
* <?php
* include('Math/BigInteger.php');
*
* $a = new Math_BigInteger(693);
* $b = new Math_BigInteger(609);
*
* $gcd = a->extendedGCD($b);
*
* echo $gcd->toString() . "\r\n"; // outputs 21
* ?>
* </code>
*
* @param Math_BigInteger $n
* @return Math_BigInteger
* @access public
*/
function gcd($n)
{
extract($this->extendedGCD($n));
return $gcd;
}
/**
* Absolute value.
*
* @return Math_BigInteger
* @access public
*/
function abs()
{
$temp = new Math_BigInteger();
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp->value = gmp_abs($this->value);
break;
case MATH_BIGINTEGER_MODE_BCMATH:
$temp->value = (bccomp($this->value, '0') < 0) ? substr($this->value, 1) : $this->value;
break;
default:
$temp->value = $this->value;
}
return $temp;
}
/**
* Compares two numbers.
*
* Although one might think !$x->compare($y) means $x != $y, it, in fact, means the opposite. The reason for this is
* demonstrated thusly:
*
* $x > $y: $x->compare($y) > 0
* $x < $y: $x->compare($y) < 0
* $x == $y: $x->compare($y) == 0
*
* Note how the same comparison operator is used. If you want to test for equality, use $x->equals($y).
*
* @param Math_BigInteger $x
* @return Integer < 0 if $this is less than $x; > 0 if $this is greater than $x, and 0 if they are equal.
* @access public
* @see equals()
* @internal Could return $this->sub($x), but that's not as fast as what we do do.
*/
function compare($y)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
return gmp_cmp($this->value, $y->value);
case MATH_BIGINTEGER_MODE_BCMATH:
return bccomp($this->value, $y->value);
}
$x = $this->_normalize($this->copy());
$y = $this->_normalize($y);
if ( $x->is_negative != $y->is_negative ) {
return ( !$x->is_negative && $y->is_negative ) ? 1 : -1;
}
$result = $x->is_negative ? -1 : 1;
if ( count($x->value) != count($y->value) ) {
return ( count($x->value) > count($y->value) ) ? $result : -$result;
}
for ($i = count($x->value) - 1; $i >= 0; $i--) {
if ($x->value[$i] != $y->value[$i]) {
return ( $x->value[$i] > $y->value[$i] ) ? $result : -$result;
}
}
return 0;
}
/**
* Tests the equality of two numbers.
*
* If you need to see if one number is greater than or less than another number, use Math_BigInteger::compare()
*
* @param Math_BigInteger $x
* @return Boolean
* @access public
* @see compare()
*/
function equals($x)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
return gmp_cmp($this->value, $x->value) == 0;
default:
return $this->value == $x->value && $this->is_negative == $x->is_negative;
}
}
/**
* Set Precision
*
* Some bitwise operations give different results depending on the precision being used. Examples include left
* shift, not, and rotates.
*
* @param Math_BigInteger $x
* @access public
* @return Math_BigInteger
*/
function setPrecision($bits)
{
$this->precision = $bits;
if ( MATH_BIGINTEGER_MODE != MATH_BIGINTEGER_MODE_BCMATH ) {
$this->bitmask = new Math_BigInteger(chr((1 << ($bits & 0x7)) - 1) . str_repeat(chr(0xFF), $bits >> 3), 256);
} else {
$this->bitmask = new Math_BigInteger(bcpow('2', $bits));
}
}
/**
* Logical And
*
* @param Math_BigInteger $x
* @access public
* @internal Implemented per a request by Lluis Pamies i Juarez <lluis _a_ pamies.cat>
* @return Math_BigInteger
*/
function bitwise_and($x)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = new Math_BigInteger();
$temp->value = gmp_and($this->value, $x->value);
return $this->_normalize($temp);
case MATH_BIGINTEGER_MODE_BCMATH:
$left = $this->toBytes();
$right = $x->toBytes();
$length = max(strlen($left), strlen($right));
$left = str_pad($left, $length, chr(0), STR_PAD_LEFT);
$right = str_pad($right, $length, chr(0), STR_PAD_LEFT);
return $this->_normalize(new Math_BigInteger($left & $right, 256));
}
$result = $this->copy();
$length = min(count($x->value), count($this->value));
$result->value = array_slice($result->value, 0, $length);
for ($i = 0; $i < $length; $i++) {
$result->value[$i] = $result->value[$i] & $x->value[$i];
}
return $this->_normalize($result);
}
/**
* Logical Or
*
* @param Math_BigInteger $x
* @access public
* @internal Implemented per a request by Lluis Pamies i Juarez <lluis _a_ pamies.cat>
* @return Math_BigInteger
*/
function bitwise_or($x)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = new Math_BigInteger();
$temp->value = gmp_or($this->value, $x->value);
return $this->_normalize($temp);
case MATH_BIGINTEGER_MODE_BCMATH:
$left = $this->toBytes();
$right = $x->toBytes();
$length = max(strlen($left), strlen($right));
$left = str_pad($left, $length, chr(0), STR_PAD_LEFT);
$right = str_pad($right, $length, chr(0), STR_PAD_LEFT);
return $this->_normalize(new Math_BigInteger($left | $right, 256));
}
$length = max(count($this->value), count($x->value));
$result = $this->copy();
$result->value = array_pad($result->value, 0, $length);
$x->value = array_pad($x->value, 0, $length);
for ($i = 0; $i < $length; $i++) {
$result->value[$i] = $this->value[$i] | $x->value[$i];
}
return $this->_normalize($result);
}
/**
* Logical Exclusive-Or
*
* @param Math_BigInteger $x
* @access public
* @internal Implemented per a request by Lluis Pamies i Juarez <lluis _a_ pamies.cat>
* @return Math_BigInteger
*/
function bitwise_xor($x)
{
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
$temp = new Math_BigInteger();
$temp->value = gmp_xor($this->value, $x->value);
return $this->_normalize($temp);
case MATH_BIGINTEGER_MODE_BCMATH:
$left = $this->toBytes();
$right = $x->toBytes();
$length = max(strlen($left), strlen($right));
$left = str_pad($left, $length, chr(0), STR_PAD_LEFT);
$right = str_pad($right, $length, chr(0), STR_PAD_LEFT);
return $this->_normalize(new Math_BigInteger($left ^ $right, 256));
}
$length = max(count($this->value), count($x->value));
$result = $this->copy();
$result->value = array_pad($result->value, 0, $length);
$x->value = array_pad($x->value, 0, $length);
for ($i = 0; $i < $length; $i++) {
$result->value[$i] = $this->value[$i] ^ $x->value[$i];
}
return $this->_normalize($result);
}
/**
* Logical Not
*
* @access public
* @internal Implemented per a request by Lluis Pamies i Juarez <lluis _a_ pamies.cat>
* @return Math_BigInteger
*/
function bitwise_not()
{
// calculuate "not" without regard to $this->precision
// (will always result in a smaller number. ie. ~1 isn't 1111 1110 - it's 0)
$temp = $this->toBytes();
$pre_msb = decbin(ord($temp[0]));
$temp = ~$temp;
$msb = decbin(ord($temp[0]));
if (strlen($msb) == 8) {
$msb = substr($msb, strpos($msb, '0'));
}
$temp[0] = chr(bindec($msb));
// see if we need to add extra leading 1's
$current_bits = strlen($pre_msb) + 8 * strlen($temp) - 8;
$new_bits = $this->precision - $current_bits;
if ($new_bits <= 0) {
return $this->_normalize(new Math_BigInteger($temp, 256));
}
// generate as many leading 1's as we need to.
$leading_ones = chr((1 << ($new_bits & 0x7)) - 1) . str_repeat(chr(0xFF), $new_bits >> 3);
$this->_base256_lshift($leading_ones, $current_bits);
$temp = str_pad($temp, ceil($this->bits / 8), chr(0), STR_PAD_LEFT);
return $this->_normalize(new Math_BigInteger($leading_ones | $temp, 256));
}
/**
* Logical Right Shift
*
* Shifts BigInteger's by $shift bits, effectively dividing by 2**$shift.
*
* @param Integer $shift
* @return Math_BigInteger
* @access public
* @internal The only version that yields any speed increases is the internal version.
*/
function bitwise_rightShift($shift)
{
$temp = new Math_BigInteger();
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
static $two;
if (empty($two)) {
$two = gmp_init('2');
}
$temp->value = gmp_div_q($this->value, gmp_pow($two, $shift));
break;
case MATH_BIGINTEGER_MODE_BCMATH:
$temp->value = bcdiv($this->value, bcpow('2', $shift));
break;
default: // could just replace _lshift with this, but then all _lshift() calls would need to be rewritten
// and I don't want to do that...
$temp->value = $this->value;
$temp->_rshift($shift);
}
return $this->_normalize($temp);
}
/**
* Logical Left Shift
*
* Shifts BigInteger's by $shift bits, effectively multiplying by 2**$shift.
*
* @param Integer $shift
* @return Math_BigInteger
* @access public
* @internal The only version that yields any speed increases is the internal version.
*/
function bitwise_leftShift($shift)
{
$temp = new Math_BigInteger();
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
static $two;
if (empty($two)) {
$two = gmp_init('2');
}
$temp->value = gmp_mul($this->value, gmp_pow($two, $shift));
break;
case MATH_BIGINTEGER_MODE_BCMATH:
$temp->value = bcmul($this->value, bcpow('2', $shift));
break;
default: // could just replace _rshift with this, but then all _lshift() calls would need to be rewritten
// and I don't want to do that...
$temp->value = $this->value;
$temp->_lshift($shift);
}
return $this->_normalize($temp);
}
/**
* Logical Left Rotate
*
* Instead of the top x bits being dropped they're appended to the shifted bit string.
*
* @param Integer $shift
* @return Math_BigInteger
* @access public
*/
function bitwise_leftRotate($shift)
{
$bits = $this->toBytes();
if ($this->precision > 0) {
$precision = $this->precision;
if ( MATH_BIGINTEGER_MODE == MATH_BIGINTEGER_MODE_BCMATH ) {
$mask = $this->bitmask->subtract(new Math_BigInteger(1));
$mask = $mask->toBytes();
} else {
$mask = $this->bitmask->toBytes();
}
} else {
$temp = ord($bits[0]);
for ($i = 0; $temp >> $i; $i++);
$precision = 8 * strlen($bits) - 8 + $i;
$mask = chr((1 << ($precision & 0x7)) - 1) . str_repeat(chr(0xFF), $precision >> 3);
}
if ($shift < 0) {
$shift+= $precision;
}
$shift%= $precision;
if (!$shift) {
return $this->copy();
}
$left = $this->bitwise_leftShift($shift);
$left = $left->bitwise_and(new Math_BigInteger($mask, 256));
$right = $this->bitwise_rightShift($precision - $shift);
$result = MATH_BIGINTEGER_MODE != MATH_BIGINTEGER_MODE_BCMATH ? $left->bitwise_or($right) : $left->add($right);
return $this->_normalize($result);
}
/**
* Logical Right Rotate
*
* Instead of the bottom x bits being dropped they're prepended to the shifted bit string.
*
* @param Integer $shift
* @return Math_BigInteger
* @access public
*/
function bitwise_rightRotate($shift)
{
return $this->bitwise_leftRotate(-$shift);
}
/**
* Set random number generator function
*
* $generator should be the name of a random generating function whose first parameter is the minimum
* value and whose second parameter is the maximum value. If this function needs to be seeded, it should
* be seeded prior to calling Math_BigInteger::random() or Math_BigInteger::randomPrime()
*
* If the random generating function is not explicitly set, it'll be assumed to be mt_rand().
*
* @see random()
* @see randomPrime()
* @param optional String $generator
* @access public
*/
function setRandomGenerator($generator)
{
$this->generator = $generator;
}
/**
* Generate a random number
*
* @param optional Integer $min
* @param optional Integer $max
* @return Math_BigInteger
* @access public
*/
function random($min = false, $max = false)
{
if ($min === false) {
$min = new Math_BigInteger(0);
}
if ($max === false) {
$max = new Math_BigInteger(0x7FFFFFFF);
}
$compare = $max->compare($min);
if (!$compare) {
return $this->_normalize($min);
} else if ($compare < 0) {
// if $min is bigger then $max, swap $min and $max
$temp = $max;
$max = $min;
$min = $temp;
}
$generator = $this->generator;
$max = $max->subtract($min);
$max = ltrim($max->toBytes(), chr(0));
$size = strlen($max) - 1;
$random = '';
$bytes = $size & 1;
for ($i = 0; $i < $bytes; $i++) {
$random.= chr($generator(0, 255));
}
$blocks = $size >> 1;
for ($i = 0; $i < $blocks; $i++) {
// mt_rand(-2147483648, 0x7FFFFFFF) always produces -2147483648 on some systems
$random.= pack('n', $generator(0, 0xFFFF));
}
$temp = new Math_BigInteger($random, 256);
if ($temp->compare(new Math_BigInteger(substr($max, 1), 256)) > 0) {
$random = chr($generator(0, ord($max[0]) - 1)) . $random;
} else {
$random = chr($generator(0, ord($max[0]) )) . $random;
}
$random = new Math_BigInteger($random, 256);
return $this->_normalize($random->add($min));
}
/**
* Generate a random prime number.
*
* If there's not a prime within the given range, false will be returned. If more than $timeout seconds have elapsed,
* give up and return false.
*
* @param optional Integer $min
* @param optional Integer $max
* @param optional Integer $timeout
* @return Math_BigInteger
* @access public
* @internal See {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap4.pdf#page=15 HAC 4.44}.
*/
function randomPrime($min = false, $max = false, $timeout = false)
{
// gmp_nextprime() requires PHP 5 >= 5.2.0 per <http://php.net/gmp-nextprime>.
if ( MATH_BIGINTEGER_MODE == MATH_BIGINTEGER_MODE_GMP && function_exists('gmp_nextprime') ) {
// we don't rely on Math_BigInteger::random()'s min / max when gmp_nextprime() is being used since this function
// does its own checks on $max / $min when gmp_nextprime() is used. When gmp_nextprime() is not used, however,
// the same $max / $min checks are not performed.
if ($min === false) {
$min = new Math_BigInteger(0);
}
if ($max === false) {
$max = new Math_BigInteger(0x7FFFFFFF);
}
$compare = $max->compare($min);
if (!$compare) {
return $min;
} else if ($compare < 0) {
// if $min is bigger then $max, swap $min and $max
$temp = $max;
$max = $min;
$min = $temp;
}
$x = $this->random($min, $max);
$x->value = gmp_nextprime($x->value);
if ($x->compare($max) <= 0) {
return $x;
}
$x->value = gmp_nextprime($min->value);
if ($x->compare($max) <= 0) {
return $x;
}
return false;
}
$repeat1 = $repeat2 = array();
$one = new Math_BigInteger(1);
$two = new Math_BigInteger(2);
$start = time();
do {
if ($timeout !== false && time() - $start > $timeout) {
return false;
}
$x = $this->random($min, $max);
if ($x->equals($two)) {
return $x;
}
// make the number odd
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
gmp_setbit($x->value, 0);
break;
case MATH_BIGINTEGER_MODE_BCMATH:
if ($x->value[strlen($x->value) - 1] % 2 == 0) {
$x = $x->add($one);
}
break;
default:
$x->value[0] |= 1;
}
// if we've seen this number twice before, assume there are no prime numbers within the given range
if (in_array($x->value, $repeat1)) {
if (in_array($x->value, $repeat2)) {
return false;
} else {
$repeat2[] = $x->value;
}
} else {
$repeat1[] = $x->value;
}
} while (!$x->isPrime());
return $x;
}
/**
* Checks a numer to see if it's prime
*
* Assuming the $t parameter is not set, this functoin has an error rate of 2**-80. The main motivation for the
* $t parameter is distributability. Math_BigInteger::randomPrime() can be distributed accross multiple pageloads
* on a website instead of just one.
*
* @param optional Integer $t
* @return Boolean
* @access public
* @internal Uses the
* {@link http://en.wikipedia.org/wiki/Miller%E2%80%93Rabin_primality_test Miller<EFBFBD>Rabin primality test}. See
* {@link http://www.cacr.math.uwaterloo.ca/hac/about/chap4.pdf#page=8 HAC 4.24}.
*/
function isPrime($t = false)
{
$length = strlen($this->toBytes());
if (!$t) {
// see HAC 4.49 "Note (controlling the error probability)"
if ($length >= 163) { $t = 2; } // floor(1300 / 8)
else if ($length >= 106) { $t = 3; } // floor( 850 / 8)
else if ($length >= 81 ) { $t = 4; } // floor( 650 / 8)
else if ($length >= 68 ) { $t = 5; } // floor( 550 / 8)
else if ($length >= 56 ) { $t = 6; } // floor( 450 / 8)
else if ($length >= 50 ) { $t = 7; } // floor( 400 / 8)
else if ($length >= 43 ) { $t = 8; } // floor( 350 / 8)
else if ($length >= 37 ) { $t = 9; } // floor( 300 / 8)
else if ($length >= 31 ) { $t = 12; } // floor( 250 / 8)
else if ($length >= 25 ) { $t = 15; } // floor( 200 / 8)
else if ($length >= 18 ) { $t = 18; } // floor( 150 / 8)
else { $t = 27; }
}
// ie. gmp_testbit($this, 0)
// ie. isEven() or !isOdd()
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
return gmp_prob_prime($this->value, $t) != 0;
case MATH_BIGINTEGER_MODE_BCMATH:
if ($this->value == '2') {
return true;
}
if ($this->value[strlen($this->value) - 1] % 2 == 0) {
return false;
}
break;
default:
if ($this->value == array(2)) {
return true;
}
if (~$this->value[0] & 1) {
return false;
}
}
static $primes, $zero, $one, $two;
if (!isset($primes)) {
$primes = array(
3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59,
61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137,
139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227,
229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313,
317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419,
421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509,
521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617,
619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727,
733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829,
839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947,
953, 967, 971, 977, 983, 991, 997
);
for ($i = 0; $i < count($primes); $i++) {
$primes[$i] = new Math_BigInteger($primes[$i]);
}
$zero = new Math_BigInteger();
$one = new Math_BigInteger(1);
$two = new Math_BigInteger(2);
}
// see HAC 4.4.1 "Random search for probable primes"
for ($i = 0; $i < count($primes); $i++) {
list(, $r) = $this->divide($primes[$i]);
if ($r->equals($zero)) {
return false;
}
}
$n = $this->copy();
$n_1 = $n->subtract($one);
$n_2 = $n->subtract($two);
$r = $n_1->copy();
// ie. $s = gmp_scan1($n, 0) and $r = gmp_div_q($n, gmp_pow(gmp_init('2'), $s));
if ( MATH_BIGINTEGER_MODE == MATH_BIGINTEGER_MODE_BCMATH ) {
$s = 0;
while ($r->value[strlen($r->value) - 1] % 2 == 0) {
$r->value = bcdiv($r->value, 2);
$s++;
}
} else {
for ($i = 0; $i < count($r->value); $i++) {
$temp = ~$r->value[$i] & 0xFFFFFF;
for ($j = 1; ($temp >> $j) & 1; $j++);
if ($j != 25) {
break;
}
}
$s = 26 * $i + $j - 1;
$r->_rshift($s);
}
for ($i = 0; $i < $t; $i++) {
$a = new Math_BigInteger();
$a = $a->random($two, $n_2);
$y = $a->modPow($r, $n);
if (!$y->equals($one) && !$y->equals($n_1)) {
for ($j = 1; $j < $s && !$y->equals($n_1); $j++) {
$y = $y->modPow($two, $n);
if ($y->equals($one)) {
return false;
}
}
if (!$y->equals($n_1)) {
return false;
}
}
}
return true;
}
/**
* Logical Left Shift
*
* Shifts BigInteger's by $shift bits.
*
* @param Integer $shift
* @access private
*/
function _lshift($shift)
{
if ( $shift == 0 ) {
return;
}
$num_digits = floor($shift / 26);
$shift %= 26;
$shift = 1 << $shift;
$carry = 0;
for ($i = 0; $i < count($this->value); $i++) {
$temp = $this->value[$i] * $shift + $carry;
$carry = floor($temp / 0x4000000);
$this->value[$i] = $temp - $carry * 0x4000000;
}
if ( $carry ) {
$this->value[] = $carry;
}
while ($num_digits--) {
array_unshift($this->value, 0);
}
}
/**
* Logical Right Shift
*
* Shifts BigInteger's by $shift bits.
*
* @param Integer $shift
* @access private
*/
function _rshift($shift)
{
if ($shift == 0) {
return;
}
$num_digits = floor($shift / 26);
$shift %= 26;
$carry_shift = 26 - $shift;
$carry_mask = (1 << $shift) - 1;
if ( $num_digits ) {
$this->value = array_slice($this->value, $num_digits);
}
$carry = 0;
for ($i = count($this->value) - 1; $i >= 0; $i--) {
$temp = $this->value[$i] >> $shift | $carry;
$carry = ($this->value[$i] & $carry_mask) << $carry_shift;
$this->value[$i] = $temp;
}
}
/**
* Normalize
*
* Deletes leading zeros and truncates (if necessary) to maintain the appropriate precision
*
* @return Math_BigInteger
* @access private
*/
function _normalize($result)
{
$result->precision = $this->precision;
$result->bitmask = $this->bitmask;
switch ( MATH_BIGINTEGER_MODE ) {
case MATH_BIGINTEGER_MODE_GMP:
if (!empty($result->bitmask->value)) {
$result->value = gmp_and($result->value, $result->bitmask->value);
}
return $result;
case MATH_BIGINTEGER_MODE_BCMATH:
if (!empty($result->bitmask->value)) {
$result->value = bcmod($result->value, $result->bitmask->value);
}
return $result;
}
if ( !count($result->value) ) {
return $result;
}
for ($i = count($result->value) - 1; $i >= 0; $i--) {
if ( $result->value[$i] ) {
break;
}
unset($result->value[$i]);
}
if (!empty($result->bitmask->value)) {
$length = min(count($result->value), count($this->bitmask->value));
$result->value = array_slice($result->value, 0, $length);
for ($i = 0; $i < $length; $i++) {
$result->value[$i] = $result->value[$i] & $this->bitmask->value[$i];
}
}
return $result;
}
/**
* Array Repeat
*
* @param $input Array
* @param $multiplier mixed
* @return Array
* @access private
*/
function _array_repeat($input, $multiplier)
{
return ($multiplier) ? array_fill(0, $multiplier, $input) : array();
}
/**
* Logical Left Shift
*
* Shifts binary strings $shift bits, essentially multiplying by 2**$shift.
*
* @param $x String
* @param $shift Integer
* @return String
* @access private
*/
function _base256_lshift(&$x, $shift)
{
if ($shift == 0) {
return;
}
$num_bytes = $shift >> 3; // eg. floor($shift/8)
$shift &= 7; // eg. $shift % 8
$carry = 0;
for ($i = strlen($x) - 1; $i >= 0; $i--) {
$temp = ord($x[$i]) << $shift | $carry;
$x[$i] = chr($temp);
$carry = $temp >> 8;
}
$carry = ($carry != 0) ? chr($carry) : '';
$x = $carry . $x . str_repeat(chr(0), $num_bytes);
}
/**
* Logical Right Shift
*
* Shifts binary strings $shift bits, essentially dividing by 2**$shift and returning the remainder.
*
* @param $x String
* @param $shift Integer
* @return String
* @access private
*/
function _base256_rshift(&$x, $shift)
{
if ($shift == 0) {
$x = ltrim($x, chr(0));
return '';
}
$num_bytes = $shift >> 3; // eg. floor($shift/8)
$shift &= 7; // eg. $shift % 8
$remainder = '';
if ($num_bytes) {
$start = $num_bytes > strlen($x) ? -strlen($x) : -$num_bytes;
$remainder = substr($x, $start);
$x = substr($x, 0, -$num_bytes);
}
$carry = 0;
$carry_shift = 8 - $shift;
for ($i = 0; $i < strlen($x); $i++) {
$temp = (ord($x[$i]) >> $shift) | $carry;
$carry = (ord($x[$i]) << $carry_shift) & 0xFF;
$x[$i] = chr($temp);
}
$x = ltrim($x, chr(0));
$remainder = chr($carry >> $carry_shift) . $remainder;
return ltrim($remainder, chr(0));
}
// one quirk about how the following functions are implemented is that PHP defines N to be an unsigned long
// at 32-bits, while java's longs are 64-bits.
/**
* Converts 32-bit integers to bytes.
*
* @param Integer $x
* @return String
* @access private
*/
function _int2bytes($x)
{
return ltrim(pack('N', $x), chr(0));
}
/**
* Converts bytes to 32-bit integers
*
* @param String $x
* @return Integer
* @access private
*/
function _bytes2int($x)
{
$temp = unpack('Nint', str_pad($x, 4, chr(0), STR_PAD_LEFT));
return $temp['int'];
}
}
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