sub Make_shiftedKey ($) {
    my $self  = shift;
    my $shift = shift;
    my $shiftIsOdd = $shift & 1;
    my $s_key = $self->{S_KEY};
    my $length_s_key = length $s_key;

    if ( $shiftIsOdd ) {
        $s_key = substr($s_key, 1);
    } else {
        # $s_key = substr($s_key, 0, $length_s_key) - 1);
        chop($s_key);
    }
    $len_s_key--;

    foreach ( 1 .. ($shift - 1) % $length_s_key ) {
    {
        # my $key = substr($s_key, 0, 1);
        # $s_key = substr($s_key, 1);
        # $s_key .= $key;

        $s_key =~ s/^(.)(.*)$/$2$1/;
    }

    $self->{S_KEY} = $s_key;
    return $s_key;
}