ldapsaisie/src/includes/libs/class.smbHash.php
Benjamin Renard 7098b3ee79 Massive change of files organisation to move all files outside web-root
The web-root directory now contains URL rewrite stuff. All PHP & static files are
in root src directory and are served via LSurl routes.
2020-05-06 12:17:35 +02:00

539 lines
17 KiB
PHP

<?php
/*
This code is part of LDAP Account Manager (http://www.sourceforge.net/projects/lam)
Copyright (C) 2004 Roland Gruber
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/**
* This class provides functions to calculate Samba NT and LM hashes.
*
* The code is a conversion from createntlm.pl (Benjamin Kuit) and smbdes.c/md4.c (Andrew Tridgell).
*
* @author Roland Gruber
*
* @package modules
*/
/**
* Calculates NT and LM hashes.
*
* The important functions are lmhash($password) and nthash($password).
*
* @package modules
*/
class smbHash {
# Contants used in lanlam hash calculations
# Ported from SAMBA/source/libsmb/smbdes.c:perm1[56]
var $perm1 = array(57, 49, 41, 33, 25, 17, 9,
1, 58, 50, 42, 34, 26, 18,
10, 2, 59, 51, 43, 35, 27,
19, 11, 3, 60, 52, 44, 36,
63, 55, 47, 39, 31, 23, 15,
7, 62, 54, 46, 38, 30, 22,
14, 6, 61, 53, 45, 37, 29,
21, 13, 5, 28, 20, 12, 4);
# Ported from SAMBA/source/libsmb/smbdes.c:perm2[48]
var $perm2 = array(14, 17, 11, 24, 1, 5,
3, 28, 15, 6, 21, 10,
23, 19, 12, 4, 26, 8,
16, 7, 27, 20, 13, 2,
41, 52, 31, 37, 47, 55,
30, 40, 51, 45, 33, 48,
44, 49, 39, 56, 34, 53,
46, 42, 50, 36, 29, 32);
# Ported from SAMBA/source/libsmb/smbdes.c:perm3[64]
var $perm3 = array(58, 50, 42, 34, 26, 18, 10, 2,
60, 52, 44, 36, 28, 20, 12, 4,
62, 54, 46, 38, 30, 22, 14, 6,
64, 56, 48, 40, 32, 24, 16, 8,
57, 49, 41, 33, 25, 17, 9, 1,
59, 51, 43, 35, 27, 19, 11, 3,
61, 53, 45, 37, 29, 21, 13, 5,
63, 55, 47, 39, 31, 23, 15, 7);
# Ported from SAMBA/source/libsmb/smbdes.c:perm4[48]
var $perm4 = array(32, 1, 2, 3, 4, 5,
4, 5, 6, 7, 8, 9,
8, 9, 10, 11, 12, 13,
12, 13, 14, 15, 16, 17,
16, 17, 18, 19, 20, 21,
20, 21, 22, 23, 24, 25,
24, 25, 26, 27, 28, 29,
28, 29, 30, 31, 32, 1);
# Ported from SAMBA/source/libsmb/smbdes.c:perm5[32]
var $perm5 = array(16, 7, 20, 21,
29, 12, 28, 17,
1, 15, 23, 26,
5, 18, 31, 10,
2, 8, 24, 14,
32, 27, 3, 9,
19, 13, 30, 6,
22, 11, 4, 25);
# Ported from SAMBA/source/libsmb/smbdes.c:perm6[64]
var $perm6 = array(40, 8, 48, 16, 56, 24, 64, 32,
39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30,
37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28,
35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,
33, 1, 41, 9, 49, 17, 57, 25);
# Ported from SAMBA/source/libsmb/smbdes.c:sc[16]
var $sc = array(1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1);
# Ported from SAMBA/source/libsmb/smbdes.c:sbox[8][4][16]
# Side note, I used cut and paste for all these numbers, I did NOT
# type them all in =)
var $sbox = array(array(array(14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7),
array( 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8),
array( 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0),
array(15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13)),
array(array(15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10),
array( 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5),
array( 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15),
array(13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9)),
array(array(10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8),
array(13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1),
array(13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7),
array( 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12)),
array(array( 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15),
array(13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9),
array(10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4),
array( 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14)),
array(array( 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9),
array(14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6),
array( 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14),
array(11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3)),
array(array(12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11),
array(10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8),
array( 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6),
array( 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13)),
array(array( 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1),
array(13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6),
array( 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2),
array( 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12)),
array(array(13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7),
array( 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2),
array( 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8),
array( 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11)));
/**
* Fixes too large numbers
*/
function x($i) {
if ($i < 0) return 4294967296 - $i;
else return $i;
}
/**
* @param integer count
* @param array $data
* @return array
*/
function lshift($count, $data) {
$ret = array();
for ($i = 0; $i < sizeof($data); $i++) {
$ret[$i] = $data[($i + $count)%sizeof($data)];
}
return $ret;
}
/**
* @param array in input data
* @param array p permutation
* @return array
*/
function permute($in, $p, $n) {
$ret = array();
for ($i = 0; $i < $n; $i++) {
$ret[$i] = $in[$p[$i] - 1]?1:0;
}
return $ret;
}
/**
* @param array $in1
* @param array $in2
* @return array
*/
function mxor($in1, $in2) {
$ret = array();
for ($i = 0; $i < sizeof($in1); $i++) {
$ret[$i] = $in1[$i] ^ $in2[$i];
}
return $ret;
}
/**
* @param array $in
* @param array $key
* @param boolean $forw
* @return array
*/
function doHash($in, $key, $forw) {
$ki = array();
$pk1 = $this->permute($key, $this->perm1, 56);
$c = array();
$d = array();
for ($i = 0; $i < 28; $i++) {
$c[$i] = $pk1[$i];
$d[$i] = $pk1[28 + $i];
}
for ($i = 0; $i < 16; $i++) {
$c = $this->lshift($this->sc[$i], $c);
$d = $this->lshift($this->sc[$i], $d);
$cd = $c;
for ($k = 0; $k < sizeof($d); $k++) $cd[] = $d[$k];
$ki[$i] = $this->permute($cd, $this->perm2, 48);
}
$pd1 = $this->permute($in, $this->perm3, 64);
$l = array();
$r = array();
for ($i = 0; $i < 32; $i++) {
$l[$i] = $pd1[$i];
$r[$i] = $pd1[32 + $i];
}
for ($i = 0; $i < 16; $i++) {
$er = $this->permute($r, $this->perm4, 48);
if ($forw) $erk = $this->mxor($er, $ki[$i]);
else $erk = $this->mxor($er, $ki[15 - $i]);
for ($j = 0; $j < 8; $j++) {
for ($k = 0; $k < 6; $k++) {
$b[$j][$k] = $erk[($j * 6) + $k];
}
}
for ($j = 0; $j < 8; $j++) {
$m = array();
$n = array();
$m = ($b[$j][0] << 1) | $b[$j][5];
$n = ($b[$j][1] << 3) | ($b[$j][2] << 2) | ($b[$j][3] << 1) | $b[$j][4];
for ($k = 0; $k < 4; $k++) {
$b[$j][$k]=($this->sbox[$j][$m][$n] & (1 << (3-$k)))?1:0;
}
}
for ($j = 0; $j < 8; $j++) {
for ($k = 0; $k < 4; $k++) {
$cb[($j * 4) + $k] = $b[$j][$k];
}
}
$pcb = $this->permute($cb, $this->perm5, 32);
$r2 = $this->mxor($l, $pcb);
for ($k = 0; $k < 32; $k++) $l[$k] = $r[$k];
for ($k = 0; $k < 32; $k++) $r[$k] = $r2[$k];
}
$rl = $r;
for ($i = 0; $i < sizeof($l); $i++) $rl[] = $l[$i];
return $this->permute($rl, $this->perm6, 64);
}
function str_to_key($str) {
$key[0] = $this->unsigned_shift_r($str[0], 1);
$key[1] = (($str[0]&0x01)<<6) | $this->unsigned_shift_r($str[1], 2);
$key[2] = (($str[1]&0x03)<<5) | $this->unsigned_shift_r($str[2], 3);
$key[3] = (($str[2]&0x07)<<4) | $this->unsigned_shift_r($str[3], 4);
$key[4] = (($str[3]&0x0F)<<3) | $this->unsigned_shift_r($str[4], 5);
$key[5] = (($str[4]&0x1F)<<2) | $this->unsigned_shift_r($str[5], 6);
$key[6] = (($str[5]&0x3F)<<1) | $this->unsigned_shift_r($str[6], 7);
$key[7] = $str[6]&0x7F;
for ($i = 0; $i < 8; $i++) {
$key[$i] = ($key[$i] << 1);
}
return $key;
}
function smb_hash($in, $key, $forw){
$key2 = $this->str_to_key($key);
for ($i = 0; $i < 64; $i++) {
$inb[$i] = ($in[$i/8] & (1<<(7-($i%8)))) ? 1:0;
$keyb[$i] = ($key2[$i/8] & (1<<(7-($i%8)))) ? 1:0;
$outb[$i] = 0;
}
$outb = $this->dohash($inb, $keyb, $forw);
for ($i = 0; $i < 8; $i++) {
$out[$i] = 0;
}
for ($i = 0; $i < 65; $i++) {
if ( isset($outb[$i]) && $outb[$i] ) {
$out[$i/8] |= (1<<(7-($i%8)));
}
}
return $out;
}
function E_P16($in) {
$p14 = array_values(unpack("C*",$in));
$sp8 = array(0x4b, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25);
$p14_1 = array();
$p14_2 = array();
for ($i = 0; $i < 7; $i++) {
$p14_1[$i] = $p14[$i];
$p14_2[$i] = $p14[$i + 7];
}
$p16_1 = $this->smb_hash($sp8, $p14_1, true);
$p16_2 = $this->smb_hash($sp8, $p14_2, true);
$p16 = $p16_1;
for ($i = 0; $i < sizeof($p16_2); $i++) {
$p16[] = $p16_2[$i];
}
return $p16;
}
/**
* Calculates the LM hash of a given password.
*
* @param string $password password
* @return string hash value
*/
function lmhash($password = "") {
$password = strtoupper($password);
$password = substr($password,0,14);
$password = str_pad($password, 14, chr(0));
$p16 = $this->E_P16($password);
for ($i = 0; $i < sizeof($p16); $i++) {
$p16[$i] = sprintf("%02X", $p16[$i]);
}
return join("", $p16);
}
/**
* Calculates the NT hash of a given password.
*
* @param string $password password
* @return string hash value
*/
function nthash($password = "") {
$password = substr($password,0,128);
$password2 = "";
for ($i = 0; $i < strlen($password); $i++) $password2 .= $password[$i] . chr(0);
$password = $password2;
$hex = $this->mdfour($password);
for ($i = 0; $i < sizeof($hex); $i++) {
$hex[$i] = sprintf("%02X", $hex[$i]);
}
return join("", $hex);
}
# Support functions
# Ported from SAMBA/source/lib/md4.c:F,G and H respectfully
function F($X, $Y, $Z) {
$ret = (($X&$Y) | ((~((int)$X))&$Z));
if ($this->x($ret) > 4294967296) {
$ret = (2*4294967296) - $this->x($ret);
}
return $ret;
}
function G($X, $Y, $Z) {
return ($X&$Y) | ($X&$Z) | ($Y&$Z);
}
function H($X, $Y, $Z) {
return $X^$Y^$Z;
}
# Ported from SAMBA/source/lib/md4.c:mdfour
function mdfour($in) {
$in = unpack("C*",$in);
$in = array_values($in);
$b = sizeof($in) * 8;
$A = array(0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476);
while (sizeof($in) > 64 ) {
$M = $this->copy64($in);
$this->mdfour64($A[0], $A[1], $A[2], $A[3], $M);
$new_in = array();
for ($i = 64; $i < sizeof($in); $i++) $new_in[] = $in[$i];
$in = $new_in;
}
$buf = $in;
$buf[] = 0x80;
for ($i = sizeof($buf) - 1; $i < 127; $i++) $buf[] = 0;
if ( sizeof($in) <= 55 ) {
$temp = $this->copy4($b);
$buf[56] = $temp[0];
$buf[57] = $temp[1];
$buf[58] = $temp[2];
$buf[59] = $temp[3];
$M = $this->copy64($buf);
$this->mdfour64($A[0], $A[1], $A[2], $A[3], $M);
}
else {
$temp = $this->copy4($b);
$buf[120] = $temp[0];
$buf[121] = $temp[1];
$buf[122] = $temp[2];
$buf[123] = $temp[3];
$M = $this->copy64($buf);
$this->mdfour64($A[0], $A[1], $A[2], $A[3], $M);
$temp = array();
for ($i = 64; $i < sizeof($buf); $i++) $temp[] = $buf[$i];
$M = $this->copy64($temp);
$this->mdfour64($A[0], $A[1], $A[2], $A[3], $M);
}
$out = array();
$temp = $this->copy4($A[0]);
for ($i = 0; $i < 4; $i++) $out[] = $temp[$i];
$temp = $this->copy4($A[1]);
for ($i = 0; $i < 4; $i++) $out[] = $temp[$i];
$temp = $this->copy4($A[2]);
for ($i = 0; $i < 4; $i++) $out[] = $temp[$i];
$temp = $this->copy4($A[3]);
for ($i = 0; $i < 4; $i++) $out[] = $temp[$i];
return $out;
}
# Ported from SAMBA/source/lib/md4.c:copy4
function copy4($x) {
$out = array();
$out[0] = $x&0xFF;
$out[1] = $this->unsigned_shift_r($x, 8)&0xFF;
$out[2] = $this->unsigned_shift_r($x, 16)&0xFF;
$out[3] = $this->unsigned_shift_r($x, 24)&0xFF;
return $out;
}
# Ported from SAMBA/source/lib/md4.c:copy64
function copy64($in) {
for ($i = 0; $i < 16; $i++) {
$M[$i] = ($in[$i*4+3]<<24) | ($in[$i*4+2]<<16) | ($in[$i*4+1]<<8) | ($in[$i*4+0]<<0);
}
return $M;
}
# Ported from SAMBA/source/lib/md4.c:mdfour64
function mdfour64(&$A, &$B, &$C, &$D, $M) {
$X = array();
for ($i = 0; $i < 16; $i++) $X[] = $M[$i];
$AA=$A;
$BB=$B;
$CC=$C;
$DD=$D;
$this->ROUND1($A,$B,$C,$D, 0, 3, $X);
$this->ROUND1($D,$A,$B,$C, 1, 7, $X);
$this->ROUND1($C,$D,$A,$B, 2, 11, $X);
$this->ROUND1($B,$C,$D,$A, 3, 19, $X);
$this->ROUND1($A,$B,$C,$D, 4, 3, $X); $this->ROUND1($D,$A,$B,$C, 5, 7, $X);
$this->ROUND1($C,$D,$A,$B, 6, 11, $X); $this->ROUND1($B,$C,$D,$A, 7, 19, $X);
$this->ROUND1($A,$B,$C,$D, 8, 3, $X); $this->ROUND1($D,$A,$B,$C, 9, 7, $X);
$this->ROUND1($C,$D,$A,$B, 10, 11, $X); $this->ROUND1($B,$C,$D,$A, 11, 19, $X);
$this->ROUND1($A,$B,$C,$D, 12, 3, $X); $this->ROUND1($D,$A,$B,$C, 13, 7, $X);
$this->ROUND1($C,$D,$A,$B, 14, 11, $X); $this->ROUND1($B,$C,$D,$A, 15, 19, $X);
$this->ROUND2($A,$B,$C,$D, 0, 3, $X); $this->ROUND2($D,$A,$B,$C, 4, 5, $X);
$this->ROUND2($C,$D,$A,$B, 8, 9, $X); $this->ROUND2($B,$C,$D,$A, 12, 13, $X);
$this->ROUND2($A,$B,$C,$D, 1, 3, $X); $this->ROUND2($D,$A,$B,$C, 5, 5, $X);
$this->ROUND2($C,$D,$A,$B, 9, 9, $X); $this->ROUND2($B,$C,$D,$A, 13, 13, $X);
$this->ROUND2($A,$B,$C,$D, 2, 3, $X); $this->ROUND2($D,$A,$B,$C, 6, 5, $X);
$this->ROUND2($C,$D,$A,$B, 10, 9, $X); $this->ROUND2($B,$C,$D,$A, 14, 13, $X);
$this->ROUND2($A,$B,$C,$D, 3, 3, $X); $this->ROUND2($D,$A,$B,$C, 7, 5, $X);
$this->ROUND2($C,$D,$A,$B, 11, 9, $X); $this->ROUND2($B,$C,$D,$A, 15, 13, $X);
$this->ROUND3($A,$B,$C,$D, 0, 3, $X); $this->ROUND3($D,$A,$B,$C, 8, 9, $X);
$this->ROUND3($C,$D,$A,$B, 4, 11, $X); $this->ROUND3($B,$C,$D,$A, 12, 15, $X);
$this->ROUND3($A,$B,$C,$D, 2, 3, $X); $this->ROUND3($D,$A,$B,$C, 10, 9, $X);
$this->ROUND3($C,$D,$A,$B, 6, 11, $X); $this->ROUND3($B,$C,$D,$A, 14, 15, $X);
$this->ROUND3($A,$B,$C,$D, 1, 3, $X); $this->ROUND3($D,$A,$B,$C, 9, 9, $X);
$this->ROUND3($C,$D,$A,$B, 5, 11, $X); $this->ROUND3($B,$C,$D,$A, 13, 15, $X);
$this->ROUND3($A,$B,$C,$D, 3, 3, $X); $this->ROUND3($D,$A,$B,$C, 11, 9, $X);
$this->ROUND3($C,$D,$A,$B, 7, 11, $X); $this->ROUND3($B,$C,$D,$A, 15, 15, $X);
$A = $this->add32(array($A, $AA)); $B = $this->add32(array($B, $BB));
$C = $this->add32(array($C, $CC)); $D = $this->add32(array($D, $DD));
}
# Needed? because perl seems to choke on overflowing when doing bitwise
# operations on numbers larger than 32 bits. Well, it did on my machine =)
function add32($v) {
$sum = array();
for ($i = 0; $i < sizeof($v); $i++) {
$v[$i] = array($this->unsigned_shift_r(($v[$i]&0xffff0000), 16), ($v[$i]&0xffff));
}
for ($i = 0; $i < sizeof($v); $i++) {
@$sum[0] += $v[$i][0];
@$sum[1] += $v[$i][1];
}
$sum[0] += ($sum[1]&0xffff0000)>>16;
$sum[1] &= 0xffff;
$sum[0] &= 0xffff;
$ret = ($sum[0]<<16) | $sum[1];
if ($this->x($ret) > 4294967296) {
$ret = (2*4294967296) - $this->x($ret);
}
return $ret;
}
# Ported from SAMBA/source/lib/md4.c:ROUND1
function ROUND1(&$a,$b,$c,$d,$k,$s,$X) {
$a = $this->md4lshift($this->add32(array($a, $this->F($b,$c,$d), $X[$k])), $s);
return $a;
}
# Ported from SAMBA/source/lib/md4.c:ROUND2
function ROUND2(&$a,$b,$c,$d,$k,$s,$X) {
$a = $this->md4lshift($this->add32(array($a, $this->G($b,$c,$d), $X[$k] + 0x5A827999)), $s);
return $a;
}
# Ported from SAMBA/source/lib/md4.c:ROUND3
function ROUND3(&$a,$b,$c,$d,$k,$s,$X) {
$a = $this->md4lshift($this->add32(array($a + $this->H($b,$c,$d) + $X[$k] + 0x6ED9EBA1)), $s);
return $a;
}
# Ported from SAMBA/source/lib/md4.c:lshift
# Renamed to prevent clash with SAMBA/source/libsmb/smbdes.c:lshift
function md4lshift($x, $s) {
$x &= 0xFFFFFFFF;
if ($this->x($x) > 4294967296) {
$x = (2*4294967296) - $this->x($x);
}
$ret = ((($x<<$s)&0xFFFFFFFF) | $this->unsigned_shift_r($x, (32-$s)));
if ($this->x($ret) > 4294967296) {
$ret = (2*4294967296) - $this->x($ret);
}
return $ret;
}
/**
* Unsigned shift operation for 32bit values.
*
* PHP 4 only supports signed shifts by default.
*/
function unsigned_shift_r($a, $b) {
$z = 0x80000000;
if ($z & $a) {
$a = ($a >> 1);
$a &= (~$z);
$a |= 0x40000000;
$a = ($a >> ($b - 1));
}
else {
$a = ($a >> $b);
}
return $a;
}
}