# PPLNS with job declaration

**URL:** <https://delvingbitcoin.org/t/pplns-with-job-declaration/1099>\
**Category:** Protocol Design\
**Created:** [August 28, 2024, 2:16pm UTC](https://delvingbitcoin.org/t/pplns-with-job-declaration/1099 "2024-08-28T14:16:11Z")\
**Posts on this page:** 1\
**Showing post:** 41

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**Author:** ![sjors](https://delvingbitcoin.org/user_avatar/delvingbitcoin.org/sjors/32/59_2.png) [@sjors](https://delvingbitcoin.org/u/sjors)\
**Post date:** [December 9, 2024, 5:25am UTC](https://delvingbitcoin.org/t/pplns-with-job-declaration/1099/41 "2024-12-09T05:25:00Z")

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I’m a bit worried about miners proposing fake block templates with absurdly high fees, thereby enjoying a relatively large payout.

This seems worse than block withholding, because such a miner could run a way with ~100% of the block reward with ~0% of the PoW.

The obvious counter measure is for the pool (or separate Job Declarator server entity, JDS) to verify every template. But this a non-trivial task, since the JDS node mempool could be very different. It may need to replace transactions its mempool with that of the template to check that it doesn’t contain a big fee transaction that’s actually unspendable.

Absurdly high fees would always trigger a new slice, so you can at least prioritize its verification.

For coinbase-only templates the JDS doesn’t know the transactions and can’t verify anything.

It’s also unclear how, in the random sample verification protocol, you would distinguish a malicious miner from a malicious pool making such templates for themselves (and ‘accidentally’ approving them).

_Perhaps a simpler solution_ is to cap the fees for all slices to whatever fees were in the found block. The fake templates, if not caught, would then have their fees reduced to a level that at least in principle they could have found. Then it’s not much worse than regular block witholding.

This also creates a disincentive to produce high value templates with ‘secret’ transactions. Template providers will want everyone else to have the good stuff in their mempool too.

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_[View the full topic](https://delvingbitcoin.org/t/pplns-with-job-declaration/1099)._