Simple Encryption and Perl

mimithebrain · 01-07-2008, 10:08 PM

I've been having lots of fun with Perl recently.

One thing that I did was to create an encryption program that encrypts the STDIN with a key using a simple XOR algorithm.

Here's my code:

Code:

#!/usr/bin/perl

die "error, provide password" if ( $#ARGV != 0 );
$masterkey = $ARGV[0];
$mklen = length($masterkey);
$chri = 0; #character index
$key = "";

while (<STDIN>){
$line = $_;
$llen = length($line);
$i = 0;
$key = "";

	while ($i < $llen)
	{
	$key = $key . substr( $masterkey, $chri, 1);
	$chri++;
	if ($chri == $mklen) {$chri = 0};
	$i++;
	}
#print $key;
print ($line ^ $key);
}

My question: What's a more efficient way of doing this?
I'd like to improve...

Thanks

j-ray · 01-08-2008, 02:52 AM

http://search.cpan.org/~kasei/Crypt-...0.06/Simple.pm

there are a lot of encryption methods and modules available at cpan.
cheers, j

bigearsbilly · 01-08-2008, 11:54 AM

how's this?

(use "<>" which accepts stdin or command line args)

Code:

#!/usr/bin/perl -w

$key = shift or die "error, provide password\n";

local $/ = undef; # slurp mode
$file = <>; # slurp whole file

$key .=  $key x int(length($file)/length($key));
$key = substr ($key, 0, length($file));  # remove excess

print ($file ^ $key);

make test data file:

Code:

$ cat /usr/dict/words  /usr/dict/words  /usr/dict/words  /usr/dict/words > input
$ wc -l input
  100572 input

your version:

Code:

$ time cat input | ./2.pl sponge  > 2

real    0m1.15s
user    0m1.11s
sys     0m0.02s

my version:

Code:

$ time ./1.pl sponge input > 1                 

real    0m0.08s
user    0m0.01s
sys     0m0.04s

check it's identical:

Code:

$ diff 1 2
$ cksum 1 2
1515968497      826652  1
1515968497      826652  2

mimithebrain · 01-08-2008, 08:44 PM

bigearsbilly,

You are a genius, thank you

bigearsbilly · 01-09-2008, 03:57 AM

I'm not a genius, just a sad geek who loves perl problems!

glad you like it, it's a more perl-ish solution, i.e. less typing!

syg00 · 01-09-2008, 04:23 AM

Quote:

Originally Posted by bigearsbilly

I'm not a genius, just a sad geek who loves perl problems!

In this country that would be "a sick bastard" ...

(meant of course as a friendly jibe - the best way)