search for: append_partition

Sorry if this is a total noob question... I've searched the archives and haven't turned up much. Not turning up much on the web in general, either. I'm working on a project and I'd like to create a Linux bootable ISO disc with an extra chunk of data **outside** the ISO space. This chunk of data might be a 10MB tar/zip. The goal would be to boot into Linux in RAM off the disc

I see there's a memtest on the Linux discs I've created... would it be possible to put another program in place (a module, perhaps?) that can calculate a hash using a certain algorithm (i.e. SHA512 or similar) to validate and print out the hash of the boot ISO before booting it? The integrity of the ISO is absolutely critical. Thanks, Bret