#1654 Add timestamp option for archive creation

[M S Cook]

When signing code, there is an option for adding a timestamp. How hard would it be to add a similar timestamp (just the timestamp) to a 7z archive? It could be done with an external file, but I'm wondering if it might not be a "selling point" to have it integrated with the archive format. It would be limited to proving "the archive hasn't changed since..." rather than who created the archive, but that would serve my needs perfectly. If I understand correctly, it is just a signature applied to a Hash value for the archive, which 7-zip already calculates, so the process would be (a) take the hash (b) submit it to be signed (via Internet) (c) receive back the signature and enclose it in some structure at the end of the archive.

I'd think it would work as an option for each archive, since a timestamp would be wasted on a lot of them, so work like the "delete after compression" tick box, which has to be set each time you want to use it.

There are a number of firms offering timestamps for code signing and other purposes, and I don't see that you have to use (or pay for) a specific one when signing code. I'd hate to have people overuse a free service, but maybe one or several firms would offer to timestamp some 7z archives as a way of getting advertising, and maybe even offer a small grant to support development. I suppose as a downside someone might try to sue the timestamping firm if the timestamp ends up on an archive containing copyrighted material or the like, but since the firm never sees the content or a listing of the archive, that shouldn't get very far.

No problem telling me I'm the only one who would want such a thing.

Thanks for a splendid program!