I was looking for a reasonably good method of encrypting stuff that was okay to use on an ipaq,
RSA seems a bit too heavy, and the RSA dolphin requires stuff that hasn't yet been ported...
I toyed with using Solitaire (p480 of Cryptonomicon)
I've got some C code for GOST, but I've not tried it, instead for a laugh:

It's an enigma machine, that'll take a varying number of rotors. I've tested it reasonably thouroughly, please report any errors ;), as it was only tested on 5.6.1.

Notes
The enigma machine here, can 'emulate' most types of enigma, from the pre-war (3 rotor w/o plug-board (AKA Steckerboard)) to the 4 Rotor, plug-boarded enigma used on submarines).

• rotorN represents a disc with a jumbled alphabet corresponding to an ordered alphabet
• reflect represents a partial rotor where letters correspond to other letters and the other letter back (i.e) A->M, M->A.
• Order is the order of occurence of the rotors, since they're interchangeable, except the reflector
• position is the starting letter for each rotor.
• Plug is the plug board where letters are mapped to other letters, as with the reflector

Using a programming language it seemed redundant to retain ring-settings.

#!/usr/bin/perl
use strict;

sub r{
        my($r,$p,$c,$n)=@_;
        $r=~s/([a-z])/$n=uc($1),uc($1)/eg && $r=~s/(.*)($p)(.*)/$2$3$1
+/;
        sub{
                if($_[0]=~/^-(.)$/){$p=('A'..'Z')[index($r,$1)]}      
+  
                else{$r=~s/(.{$_[1]})(.*)/$2$1/ if $#_>0;$p=substr($r,
+ord($_[0])-65,1)}
                ($p,eval $c)
        }                   
}

my $d=0;
%_=map{chomp;(split/:/,$_,2)}<DATA>; # These four lines read the setti
+ng data ;)
$_{$_}=[split/ /,$_{$_}] for qw(position plug order);
$_{'plug'}={map{@_=(split//);@_[0,1,1,0]}@{$_{'plug'}} };
$_{'switch'}=['$n eq $p','$d=($n eq $p),$d','$d?!($d=0):0','0'];

@_=map{
    &r($_{$_{'order'}->[$_]},
       $_{'position'}->[$_],
       $_{'switch'}->[$_])
    }(0..$#{$_{'order'}});

s/([a-z])/$_=uc($1);                             # Enigma takes only a
+lpha chars.
my($a,$i)=(1);$_=$_{'plug'}->{$_}|| $_;          # go through stecker 
+plugs.     
for $i(0..$#_){($_,$a)=&{$_[$i]}($_,$a)}         # go through rotors.
$_=substr($_{'reflect'},ord($_)-65,1);           # go through reflecto
+r plate.
for($i=$#_;$i>=0;){($_,$a)=&{$_[$i--]}("-$_")}   # go back through rot
+ors     
$_=$_{'plug'}->{$_}|| $_/eigx && print while(<>) # undergo steckering.
+   

__END__                                                               
rotor1:EKMFLGDqVZXNTOWYHUSPAIBRCJ
rotor3:AJDKSIRUXBLHWTMCQGZNPYFVOe
rotor2:BDFHJLCPRTXvZNYEIWGAKMUSQO
rotor4:ESOVPZjAYQUIRHXlNFTGKDCMWB
reflect:YRUHQSLDPXNGOKMIEBFZCWVJAT
order:rotor1 rotor3 rotor2
position:D M Z A                  
plug: AT MX CD GR
[download]

Update: Bwahahaha.. I was going to write GOST in Perl and someones already done it, look... :(

Update: You know how it is when you keep whittling away at something : It's a Shark

--

Brother Frankus. (TJRX OSDKVMG YPBO PKGHZP)

¤