sub encrypt {
    my $x = shift;
    chomp $x;
    return reverse substr crypt( $x, 'ar' ), 2;
}

# choose a random dictionary word
my $dictionary = '/usr/share/dict/words';
my $secret_word;

open my $dict_fh, '<', $dictionary
    or die "Can't read '$dictionary': $!";
my $line_no = 0;
while ( my $word = <$dict_fh> ) {
    chomp $word;
    $secret_word = $word if rand() < 1/++$line_no;
}
close $dict_fh or die "Can't close dict: $!";

print "my secret word is: $secret_word\n";
my $encrypted_word = encrypt( $secret_word );
undef $secret_word;

# figure out which word it was
open $dict_fh, '<', $dictionary
    or die "Can't read '$dictionary': $!";
while ( my $word = <$dict_fh> ) {
    chomp $word;
    if ($encrypted_word eq encrypt($word)) {
        print "secret word is: $word\n";
        last;
    }
}
close $dict_fh or die "Can't close dict: $!";