Timestamping signed documents or detached signature files

[Wiktor Kwapisiewicz]

> Thank you very much for the additional infos and links, i will read them
> all.

Oh, I forgot to mention that timestamping using blockchains is actually 
very easy, for example I timestamped my key's fingerprint:

https://keyserver.ubuntu.com/pks/lookup?fingerprint=on&search=0x653909A2F0E37C106F5FAF546C8857E0D8E8F074&op=vindex

(look for timestamp+bitcoin-transaction at metacode.biz 
afcb092c5ca6409526d18ae9cf22d3b55d37e723eb1b74e3f84f7e6b052a162a)

And you can check out the transaction here:
https://blockexplorer.com/api/tx/afcb092c5ca6409526d18ae9cf22d3b55d37e723eb1b74e3f84f7e6b052a162a

(look for "OP_RETURN 653909a2f0e37c106f5faf546c8857e0d8e8f074" that is 
my key's fingerprint).

If you convert "time": 1507539820 seconds from there to date you'll get 
something like 2017-10-09T09:03:40.000Z.

OpenTimestamps (I think) uses Merkle trees to minimize fees but the 
downside is that the hash is not directly embedded in the blockchain and 
you need the extra files to reconstruct the tree root.

Have a nice day!

Kind regards,
Wiktor

-- 
https://metacode.biz/@wiktor