I’m far from an expert, but anything on standards JIS X6257 / ISO 18630 would probably be a good start. It’s an open standard for 100+ year discs.

Otherwise probably best to look into accelerated aging studies. For technology that’s less that 100 yrs old to claim 100 or 1000 is a bit uncertain but accelerated aging is probably the closest to a best guess. I recall skimming over a third party lab saying Verbatim gold foil archival DVDs were estimated to last 30-120 years depending on storage methods and luck, but never saved the link.

Oh yeah, stick it in the sun or a damp box and either will probably be bad in weeks instead of decades or centuries. But supposedly they’ll meet those lifespans good at room temp

Kinda funny, I was just writing about archival media this morning. Verbatim makes DVDs & Blue Rays that last ~100 years, and M-DISC makes ones that’ll last ~1000 years. And the Verbatim Blu Rays run ~$0.036 per gig.

Decentralized encrypted email.

Create a key, identify it by a hash of it, and encrypt all mail sent to the account with the key. Allow it to run on top of regular email using one or more email addresses as an alias, but have the key itself be the identifier.

Client 1 creates a key pair > uploads email address(es)/"aliases " that client controlls (signed with key pair) > client 2 searches for emails based on client 1’s key or aliases > client 2 sends email through one or more of the accepted inboxes encrypted with public key > client 1 reads encrypted email.

Basically a modernized version of PGP that also handles identification, and similar to how it’s been proposed to change Matrix accounts to in order to make them decentralized.