From cef4d6112051fd954bbc3e0c5b7daff2a8a249d1 Mon Sep 17 00:00:00 2001 From: Mark Henderson Date: Mon, 6 Apr 2026 11:28:55 -0400 Subject: [PATCH 1/3] add rationale for the 60/40 fee split in ZIP-235 Summarize teor's security argument from the community forum: an equal or miner-favoring split creates rollback incentives as issuance drops, and an asymmetric split aids implementation correctness by making fraction-swapping bugs detectable. Co-Authored-By: Claude Opus 4.6 (1M context) --- zips/zip-0235.md | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/zips/zip-0235.md b/zips/zip-0235.md index df8b840ea..d464c1326 100644 --- a/zips/zip-0235.md +++ b/zips/zip-0235.md @@ -142,6 +142,25 @@ a year. If 60% of these fees are removed from circulation, that would be 210.864 ZEC per year. [^zsf-fee-estimator] +## Rationale for the 60/40 split + +An asymmetric fee split favoring the removal mechanism is preferred for two +reasons: + +1. An equal split, or a split that favors miners creates a long-term security +concern. As issuance approaches zero, the proportion of fee revenue that a +miner can recoup through future block subsidies depends on their share of +network hash rate. Miners would face an incentive to roll back a preceding +block whenever the fee difference between adjacent blocks exceeds their +mining costs plus current issuance. By directing a larger share (60%) to the +removal mechanism and a smaller share (40%) to miners, the block-to-block +fee variation visible to miners is reduced, narrowing the window in which +rollback attacks are profitable.[^nsm-incentives] +2. An asymmetric split aids implementation correctness. Equal fractions +make it impossible to detect certain classes of bugs, such as swapping +the miner and removal fractions, or swapping the consensus checks on those +amounts. Any split other than 50/50 makes such errors observable in testing. + ## Considerations for the Future If transaction fees were to increase, further modifications can easily be @@ -192,4 +211,6 @@ ZIP 233 ("NSM: Removing Funds From Circulation" [^zip-0233]). [^zsf-fee-estimator]: [GitHub repository eigerco/zsf-fee-estimator](https://github.com/eigerco/zsf-fee-estimator) +[^nsm-incentives]: [Zcash Community Forum — Network Sustainability Mechanism (NSM), post by teor](https://forum.zcashcommunity.com/t/network-sustainability-mechanism-nsm/42703/104) + [^eip-1559]: [EIP-1559: Fee market change for ETH 1.0 chain](https://eips.ethereum.org/EIPS/eip-1559) From c83f2eaa8276d3c9bef78ab3537abff67f13e245 Mon Sep 17 00:00:00 2001 From: Mark Henderson Date: Thu, 9 Apr 2026 10:55:41 -0400 Subject: [PATCH 2/3] fix: move footnote --- zips/zip-0235.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/zips/zip-0235.md b/zips/zip-0235.md index d464c1326..1ba58c2f7 100644 --- a/zips/zip-0235.md +++ b/zips/zip-0235.md @@ -145,7 +145,7 @@ year. [^zsf-fee-estimator] ## Rationale for the 60/40 split An asymmetric fee split favoring the removal mechanism is preferred for two -reasons: +reasons. [^nsm-incentives] 1. An equal split, or a split that favors miners creates a long-term security concern. As issuance approaches zero, the proportion of fee revenue that a @@ -155,7 +155,7 @@ block whenever the fee difference between adjacent blocks exceeds their mining costs plus current issuance. By directing a larger share (60%) to the removal mechanism and a smaller share (40%) to miners, the block-to-block fee variation visible to miners is reduced, narrowing the window in which -rollback attacks are profitable.[^nsm-incentives] +rollback attacks are profitable. 2. An asymmetric split aids implementation correctness. Equal fractions make it impossible to detect certain classes of bugs, such as swapping the miner and removal fractions, or swapping the consensus checks on those From e739f156a5ac38a60e6758b694a7c69335d06ac6 Mon Sep 17 00:00:00 2001 From: Mark Henderson Date: Thu, 9 Apr 2026 12:02:57 -0400 Subject: [PATCH 3/3] Update zips/zip-0235.md Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com> --- zips/zip-0235.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/zips/zip-0235.md b/zips/zip-0235.md index 1ba58c2f7..4fd55f977 100644 --- a/zips/zip-0235.md +++ b/zips/zip-0235.md @@ -147,7 +147,7 @@ year. [^zsf-fee-estimator] An asymmetric fee split favoring the removal mechanism is preferred for two reasons. [^nsm-incentives] -1. An equal split, or a split that favors miners creates a long-term security +1. An equal split, or a split that favors miners, creates a long-term security concern. As issuance approaches zero, the proportion of fee revenue that a miner can recoup through future block subsidies depends on their share of network hash rate. Miners would face an incentive to roll back a preceding