sub encode_base32 {
   ... based on encode_base64 ...
}

sub decode_base32 {
   ... based on decode_base64 ...
}

sub compress_data {
   my ($year, $subject, $author, @chemicals) = @_;

   carp(...) if $year    < 0 || $year    > 65535;
   carp(...) if $subject < 0 || $subject > 65535;
   carp(...) if $author  < 0 || $author  > 65535;
   carp(...) if @chemicals > 11;
   carp(...) if grep { $_ == 65535 } @chemicals;

   push(@chemicals, (65535)x(11-@chemicals));

   return pack('n*', $year, $subject, $author, @chemicals);
}

sub decompress_data {
   my ($data) = @_;
   my ($year, $subject, $author, @chemicals) = unpack('n*', $data);
   @chemicals = grep { $_ != 65535 } @chemicals;
   return ($year, $subject, $author, @chemicals);
}


$file_name = encode_base32(compress_data(...));

(...) = decompress_data(decode_base32($file_name));