# Sharing block templates **URL:** \ **Category:** Implementation\ **Tags:** mempool, block-relay\ **Created:** [August 5, 2025, 7:08pm UTC](https://delvingbitcoin.org/t/sharing-block-templates/1906 "2025-08-05T19:08:31Z")\ **Posts on this page:** 1\ **Showing post:** 16
**Author:** ![gmaxwell](https://delvingbitcoin.org/letter_avatar_proxy/v4/letter/g/fbc32d/32.png) [@gmaxwell](https://delvingbitcoin.org/u/gmaxwell)\ **Post date:** [August 22, 2025, 11:34am UTC](https://delvingbitcoin.org/t/sharing-block-templates/1906/16 "2025-08-22T11:34:53Z")
Right my intuition is that you want to send some check value to confirm you got a correct decode regardless. You could just use a hash, but using a minisketch has the advantage of letting you do more than just pass-fail. An implementation could start by just using it as a pass/fail like a hash. When doing the math on short-id collisions it turns out that the failure rate is dominated by cases where there is just a one or two collisions (unless the short-id is woefully too small), so being able to disambiguate just a couple is potentially useful. Assuming it’s all unsalted the sketch is very close to free to compute, like store w/ txn their sketch values, and you just xor them when building the template (either on the sender side or as the receiver decodes). I suggested size 8 kind of as a random example, with the thought in mind that overly small minisketches have a non-negligible probability of false decode. Though I didn’t bother to run the calculator to check (there is a function in the library), IIRC it’s cryptographically negligible by size 8 for 64-bit hashes but it might also be by size 4. Information theoretically it should be possible to decode minisketch sketches well beyond the size limit if you happen to have a list of candidate elements that you expect to be more likely in the difference – like your own mempool or a list of collisions. Unfortunately we don’t currently know of a decoder that can exploit that which has subexponential complexity. So like a 64bit \* 8 element sketch could teach you 8 elements that you’re missing, but it probably could tell you about removing 30 extra elements you have that you shouldn’t out of a collection of 1000. (the exponential decoder is the one that just brute force tries toggling every combination of your set then runs the ordinary quadratic decoder). I only mention it because this is a case where it would be handy to go beyond the bound, but it’s really a sidebar unless someone figures out how to make it tractable 😛 If the receiver picks the salt for the ordinary short ids and has been caching it all along then it’s very cheap to do the decode anyways, so I don’t know that your third example is that compelling. --- _[View the full topic](https://delvingbitcoin.org/t/sharing-block-templates/1906)._