#!/usr/bin/perl -wT #use warnings and use taint mode.

use strict;

use CGI qw/:standard/;
use GnuPG::Interface;


my $q = new->CGI;

my $tainted_plain_str = $q->param('plainStr');
my $plain_str = # insert code to untaint $tainted_plain_str

print $q->header;
print $q->start_html('A webpage');

# Do your stuff with GnuPG::Interface.
# Print out your encrypted string.

print $q->end_html;