Bit shifting and php-versions

[mogster]

I'm sitting here with a rope around my neck and a big box of sleeping pills, wondering if it's time to just end it all.

But found out that a last appeal here at phpbuilder might save my neck 😃

Problem:
I've got a 3DES-encryption script written in php which cooperates with a Javascript to perform encryption routines to bring passwords safely from client to server.
There's a lot of bit-shifting involved, and it all works fine.
Sometimes...
It seems that different php-versions interprets this in different ways.
Examples:
On Linux/php 4.2.2
On SunOS 9/php 4.3.1
Same code on both sites, but different output when shifting bits.

Heres the code:

## This enhances php to accept zero fill shift right bitwise operator >>> ##
function zeroFill($a, $b) { 
$z = hexdec(80000000); 
if ($z & $a) { 
$a >>= 1; 
$a &= (~ $z); 
$a |= 0x40000000; 
$a >>= ($b-1); 
} else { 
$a >>= $b; 
} 
return $a; 
}

## Just a test - this is what is exec'ed in the scripts on the links ##
$left = -890149274;
$right = -1236965530;
$temp = 53283;
echo "<br>right: ".$right."<br>";
echo "<br>left: ".$left."<br>";
echo "<br>Temp: ".$temp."<br>";
$temp = ((zeroFill($left, 2)) ^ $right) & 0x33333333; $right ^= $temp; $left ^= ($temp << 2);
echo "<br>right2: ".$right."<br>";
echo "<br>left2: ".$left."<br>";
echo "<br>Temp2: ".$temp."<br>";

The zeroFill-function is the only way I've found to extend php with this operand.
Anyone?:p

knutm

[mogster]

Oh, here's the Javascript equivalent:

temp = ((left >>> 2) ^ right) & 0x33333333; right ^= temp; left ^= (temp << 2);

Note:
Anyone solving this will be GUARANTEED a prominent place in my evening prayers for years to come😉

knutm

[mogster]

dum-ti-dum
Just strolling past, looking if there's any answers to this (incredibly interesting) problem 😃

knutm

[edwardsbc]

What architecture is the SunOS running on? Are the integer registers the same size between the two platforms? The PHP Manual has one note indicating that underlying CPU architecture can cause differences in bitwise results.

[diego25]

Yeah, I also think that is the problem. Is one of the systems 64-bit and the other 32-bit?

Diego

[mogster]

Yeah, that's true.
The sunos is 64-bit, and runs on sparc-architecture (Sun X1 UltraSparc III).

Will this affect the bit-shifting? :eek:

Hmmmm.. how would I work around this, do you think?
I'm not very warmed to the bit-shifting stuff, and the script is a perl2php-hack I wrote before christmas.

knutm 😃

[mogster]

Here's a more extensive list of servers which the code is tested on:

Does not work:
Linux on sparc/php 4.0.6
Do work:
Linux on i686/php 4.1.2
Do work:
Linux on unknown/php 4.2.2
Does not work:
Linux on i686/php 4.0.4pl1
Does not work:
Sunos9 on sparc/php 4.3.1

This snippet of code works on every server but the last, but the full version fails further down in the script on servers running php lower than 4.1.2.
Erm.. the server running sunos above runs 64-bit on Ultrasparc II (Ultra2). The server I'm working at is to replace the 4.0.4pl1-installation, and is the X1/UltraSparcIII...

knutm

[mogster]

FYI:
Found the error - seems that the values in the zeroFill()-function needed to be specified as integers:

# This takes care of bit-shuffling, and enhances php to accept zero fill shift right bitwise operator >>> ## 
function zeroFill($a, $b) { 
$z = hexdec(80000000);
$z = (int)$z;
$a = (int)$a;
$b = (int)$b;
if ($z & $a) { 
 $a >>= 1; 
 $a &= (~ $z); 
 $a |= 0x40000000; 
 $a >>= ($b-1); 
} else { 
 $a >>= $b; 
} 
return $a; 
}

I'm a much happier man today 😃

knutm