#!/usr/bin/perl -w

use strict;
use Crypt::RC4;

print "usage: $0 [ crypt | view ] <filename> <password>\n" and exit unless validateInput(@ARGV);

my ($option, $file, $password) = @ARGV;
my ($plaintext, $crypted, $decrypted);

$plaintext = openFile($file);

if ($option eq 'view') {
  
  $decrypted = RC4($password, $plaintext);
  print "$decrypted\n";
  
} elsif ($option eq 'crypt') {
  
  my $outputname = "$file" . '.enc';
  $crypted = RC4($password, $plaintext);
  open FH, ">$outputname" or print "error: $!\n" and exit;
  print FH "$crypted";
  close FH;
  print "$file encrypted with the given password\nnew filename $outputname\n";
}

sub openFile {

my $filename = shift;
my $data;
open FH, "<$filename" or print "error: $!\n" and exit;
while (<FH>) {
  $data .= $_;
}
close FH;
return $data;
}

sub validateInput {

return undef unless @_ == 3;
return undef unless ($_[0] =~ /view|crypt/);
return undef unless (-e $_[1]);
1;
}