A simple example:

use strict;
use warnings;

my $plaintext = 'We are discovered. Flee at once!';
my $key = 'CorrectBatteryHorseStaple';

print "Original message: $plaintext\n";
my $ciphertext = cypher($plaintext,$key);
my $ucode = pack("u",$ciphertext);
print " Encoded message: $ucode (uuencoded)\n";
my $decoded = cypher($ciphertext,$key);
print " Decoded message: $decoded\n";

sub cypher {
  my $plain = shift; my $key = shift;
  my $i=0;
  $key x= ( 1 + length($plain)/length($key) );
  return $plain ^ substr($key,0,length($plain));
}

[download]

It requires a key that is XORd with the plaintext to produce the ciphertext. Calling the subroutine again with the ciphertext and the same key will reproduce the plaintext.

Update: copied example into response, against future changes to scratchpad. Updated again to use uuencode to display key, also removed unnecessary loop.

1 Peter 4:10

In reply to Re: Encryption/Decryption Program: by GotToBTru
in thread Encryption/Decryption Program: by Perl Beginner01

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