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- the previous fix i implemented for _barrett() when the modulo has an odd number of digits didn't always work

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git-svn-id: http://phpseclib.svn.sourceforge.net/svnroot/phpseclib/trunk@75 21d32557-59b3-4da0-833f-c5933fad653e
This commit is contained in:
Jim Wigginton 2010-01-05 18:38:02 +00:00
parent 7ecd481002
commit b1787c1529
1 changed files with 16 additions and 9 deletions
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25
phpseclib/Math/BigInteger.php
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@ -72,7 +72,7 @@
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVI Jim Wigginton
* @license http://www.gnu.org/licenses/lgpl.txt
* @version $Id: BigInteger.php,v 1.22 2010-01-04 07:59:01 terrafrost Exp $
* @version $Id: BigInteger.php,v 1.23 2010-01-05 18:38:02 terrafrost Exp $
* @link http://pear.php.net/package/Math_BigInteger
*/
@ -1756,11 +1756,6 @@ class Math_BigInteger {
$m_value = $m->value;
$m_length = count($m_value);
if ($m_length & 1) {
$m_value[] = 0;
$m_length++;
}
// if ($this->compare($m->_square()) >= 0) {
if (count($this->value) > 2 * $m_length) {
list(, $temp) = $this->divide($m);
@ -1806,6 +1801,10 @@ class Math_BigInteger {
$lsd->_trim();
$n = $lsd->add($msd->multiply($m1)); // m.length + (m.length >> 1) + 1
if ($m_length & 1) {
return $n->_regularBarrett($m);
}
// (m.length + (m.length >> 1) + 1) - (m.length - 1) == (m.length >> 1) + 2
$temp_value = array_slice($n->value, $m_length - 1);
// if even: ((m.length >> 1) + 2) + (m.length >> 1) == m.length + 2
@ -1821,7 +1820,7 @@ class Math_BigInteger {
// at this point, if m had an odd number of digits, we'd be subtracting a 2 * m.length - (m.length >> 1) digit
// number from a m.length + (m.length >> 1) + 1 digit number. ie. there'd be an extra digit and the while loop
// following this comment would loop a lot (hence our conditionally adding a 0 as the most significant digit).
// following this comment would loop a lot (hence our calling _regularBarrett() in that situation).
$result = $n->subtract($temp);
@ -1870,18 +1869,23 @@ class Math_BigInteger {
$temp_value = &$temp->value;
$temp_value = $this->_array_repeat(0, 2 * $n_length);
$temp_value[] = 1;
list($cache[MATH_BIGINTEGER_DATA][], ) = $temp->divide($n);
list($cache[MATH_BIGINTEGER_DATA][], ) = $temp->divide($n); // m.length
}
$this_value = $this->value;
$this_value = $this->value; // 2 * m.length
// 2 * m.length - (m.length - 1) = m.length + 1
$temp->value = array_slice($this_value, $n_length - 1);
// (m.length + 1) + m.length = 2 * m.length + 1
$temp = $temp->multiply($cache[MATH_BIGINTEGER_DATA][$key]);
$temp_value = &$temp->value;
// (2 * m.length + 1) - (m.length - 1) = m.length + 2
$temp_value = array_slice($temp_value, $n_length + 1);
$result = new Math_BigInteger();
// m.length + 1
$result->value = array_slice($this_value, 0, $n_length + 1);
// m.length + 1
$temp = $temp->_multiplyLower($n, $n_length + 1);
// $temp->value == array_slice($temp->multiply($n)->value, 0, $n_length + 1)
@ -1896,7 +1900,10 @@ class Math_BigInteger {
$result = $result->add($corrector);
}
// at this point, we're subtracting a number with m.length + 1 digits from another number with m.length + 1 digits
$result = $result->subtract($temp);
while ($result->compare($n) > 0) {
$result = $result->subtract($n);
}