2017-08-28 18:13 GMT+02:00 Greg Sanders : > Is there any reason to believe that you need Bitcoin "full security" at > all for timestamping? > This is a little bit out of the main topic of the email which is the savings in bandwidth in transmitting headers, any comment about that? P.S. As a personal experience timestamping is nowadays used to prove date and integrity of private databases containing a lot of value, so yes, in that cases I will go with Bitcoin "full security" > > On Mon, Aug 28, 2017 at 11:50 AM, Riccardo Casatta via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: > >> Hi everyone, >> >> the Bitcoin headers are probably the most condensed and important piece >> of data in the world, their demand is expected to grow. >> >> When sending a stream of continuous block headers, a common case in IBD >> and in disconnected clients, I think there is a possible optimization of >> the transmitted data: >> The headers after the first could avoid transmitting the previous hash >> cause the receiver could compute it by double hashing the previous header >> (an operation he needs to do anyway to verify PoW). >> In a long stream, for example 2016 headers, the savings in bandwidth are >> about 32/80 ~= 40% >> without compressed headers 2016*80=161280 bytes >> with compressed headers 80+2015*48=96800 bytes >> >> What do you think? >> >> >> In OpenTimestamps calendars we are going to use this compression to give >> lite-client a reasonable secure proofs (a full node give higher security >> but isn't feasible in all situations, for example for in-browser >> verification) >> To speed up sync of a new client Electrum starts with the download of a >> file ~36MB containing >> the first 477637 headers. >> For this kind of clients could be useful a common http API with fixed >> position chunks to leverage http caching. For example /headers/2016/0 >> returns the headers from the genesis to the 2015 header included while >> /headers/2016/1 gives the headers from the 2016th to the 4031. >> Other endpoints could have chunks of 20160 blocks or 201600 such that >> with about 10 http requests a client could fast sync the headers >> >> >> -- >> Riccardo Casatta - @RCasatta >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >> >> > -- Riccardo Casatta - @RCasatta