#!/usr/bin/perl
use strict;
use warnings;
use Crypt::CBC;
use Digest::MD5 qw/md5_hex/;

warn "Not enough arguments, use\naes.txt <pass> <file> <de-/encrypt>\n" if scalar @ARGV < 3;
my ($password, $file_name, $action) = @ARGV;
start_up($action, 0, $file_name);

sub start_up {
  my $action = shift;
  my $clean_up = shift;
  my $file_name = shift;

  my $is_file = -f $file_name ? 1 : 0;
  return unless $is_file;
  $action = $action eq 'e' ? 'encrypting' : 'decrypting';
  crypto($file_name, $clean_up, $action);
}

sub crypto {
  my $file = shift;
  my $clean_up = shift;
  my $action = shift;

  my $suffix = $action eq 'encrypting' ? 'aes' : 'no';
  my $cipher = Crypt::CBC->new(-key    => md5_hex($password),
                               -cipher => 'Rijndael');
  my $buffer;
  my $buffer_size = 1024;
  print "Begin $action $file...";
  $cipher->start($action);
  open(SOURCEFILE, $file) or die $!;
  open DESTFILE, '>', "$file.$suffix" or die $!;
    while (sysread(SOURCEFILE,$buffer,$buffer_size)) {
      $buffer = $cipher->crypt($buffer);
      print DESTFILE $buffer;
    }
  close DESTFILE;
  close SOURCEFILE or die $!;
  $cipher->finish;
  print " done!\n";
  if ($clean_up) {
  #...
  }
  return 1;
}