Welcome to the MacNN Forums.

nonhuman · Dec 23, 2001, 10:37 AM

Okay, being on break as I am, I'm generally pretty bored. I just reread Cryptonimicon and for the hell of it decided to try out "Solitaire" or "Pontifex" crypto system that's described in the book. The following is provided in the book as the perl version of the encryption algorith:

<BLOCKQUOTE>code:<HR><pre>#!/usr/bin/perl -s
$f=$d?-1:1;$D=pack('C*',33..86)$p=shift;
$p=~y/a-z/A-Z/;$U='$D=~s/(.*)U$/U$1/;
$D=~s/U(.)/$1U/;';($V=$U)=~s/U/V/g;
$p=~s/[A-Z]/$k=ord($&)-64,$e/eg;$k=0;
while(<> ){y/a-z/A-Z/;y/A-Z//dc;$o.=$_}$o.='X'
while length ($o)%5&&!$d;
$o=~s/./chr(($f*&e+ord($&)-13)%26+65)/eg;
$o=~s/X*$// if $d;$o=~s/.{5}/$& /g;
print"$o/n";sub v{$v=ord(substr($D,$_[0]))-32;
$v>53?53:$v}
sub w{$D=~s/(.{$_[0]})(.*)(.)/$2$1$3/}
sub e{eval"$U$V$V";$D=~s/(.*)([UV].*[UV])(.*)/$#$@$!/;
&w(&v(53));$k?(&w(&k))

$c=&v(&v(0)),$c>52?&e:$c)}[/code]

Knowing absolutely nothing about perl as I do (I intend to teach myself all about it, hopefully soon), I'm at a bit of a loss about what to do after making this into a nice little file in Pico. Obviously I would want to run the script (called, creatively enough, "Pontifex"), but even as root "./ Pontifex" tells me "./: Permission denied". Can anyone offer some advice?

davechen · Dec 23, 2001, 10:45 AM

You need to change permission of the file to make it executable.

chmod 755 Pontifex

I tried to run the script, and it's not valid perl. Must be some typos.

dave

nonhuman · Dec 23, 2001, 11:01 AM

Originally posted by davechen:
You need to change permission of the file to make it executable.

chmod 755 Pontifex

I tried to run the script, and it's not valid perl. Must be some typos.

dave

Hmm, I changed the permissions, and I retyped it out from the book (so it should be correct now). However, I still get the permission denied crap.

davechen · Dec 23, 2001, 12:42 PM

You say you type "./ Pontifex"

Are you sure you want that space? The message "./: Permission denied"
says to me that it's trying to execute the current directory, not the
actual script.

Jelle Monkmater · Dec 23, 2001, 04:17 PM

Originally posted by davechen:
You need to change permission of the file to make it executable.

chmod 755 Pontifex

I tried to run the script, and it's not valid perl. Must be some typos.

dave

Actually, the Perl in the book is not very well writtten. Not only is it totally illegible (bad, bad form!), but it doesn't work either -- there's a mistake in the program.

And how do I know this? I tried the same. Then, when things were not working and running, I had a look at the code, just to see what it did, and my conclusion was that it was not a particularly helpful program for finding out what that encryption thingamabob does exactly.

So I wrote my own, in Perl, in the way that I understood the original Pontifex/Solitaire code to be, together with a little more manageable key (a stack of 52 cards is funny for 5 minutes when trying to encrypt a message, but it's not that fun after those five minutes).

If you're interested, I can post my commented code here -- it should provide you with some insight.

davechen · Dec 23, 2001, 10:54 PM

I did a google search on Pontifex and Solitaire and found this URL:
http://www.ciphergoth.org/crypto/solitaire/

Looks like working C and Perl code of the algorithm.

dave

nonhuman · Dec 24, 2001, 04:27 AM

Originally posted by davechen:
I did a google search on Pontifex and Solitaire and found this URL:
http://www.ciphergoth.org/crypto/solitaire/

Looks like working C and Perl code of the algorithm.

dave

Cool, that one works. Thanks.