# Reducing nullifier set 'state growth'

**URL:** <https://forum.aztec.network/t/reducing-nullifier-set-state-growth/155>\
**Category:** Aztec\
**Tags:** specs, nullifiers\
**Created:** [January 5, 2023, 4:19pm UTC](https://forum.aztec.network/t/reducing-nullifier-set-state-growth/155 "2023-01-05T16:19:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Mike](https://dub1.discourse-cdn.com/flex013/user_avatar/forum.aztec.network/mike/32/7_2.png) [@Mike](https://forum.aztec.network/u/Mike)\
**Post date:** [January 5, 2023, 4:19pm UTC](https://forum.aztec.network/t/reducing-nullifier-set-state-growth/155/1 "2023-01-05T16:19:57Z")

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There’s a ‘Nullifier set state growth’ problem with zcash-like protocols like ours. The amount of nullifier data to store grows with every transaction, and can never be deleted by full nodes.

- If Aztec 3 has 1 tps, and if each tx created only 2 new nullifiers, that’d be nullifier state growth of 1tx \* 2nullifiers \* 32bytes \* 31,536,000sec/yr = 2GB per year.
- If Aztec 3 has 10tps, and each kernel circuit allows for 16 new nullifiers, that’d be 10tx \* 16nullifiers \*… = 161 GB/yr  
And if we get more ambitious with scaling, the state growth increases.

Case study: the ZCash blockchain has apparently been growing at 0.78GB/day in the latter half of 2022, apparently due to an attacker spamming the chain with cheap txs which create nullifiers. (It quadrupled in size in 4 months). [Zcash Blockchain Size—Risks? - General - Zcash Community Forum](https://forum.zcashcommunity.com/t/zcash-blockchain-size-risks/43126)

[This proposal](https://github.com/0xPolygonMiden/miden-vm/discussions/356) from our friends at Polygon Miden is the best proposal I’ve seen to combat this (it’s inspired by an old proposal from Vitalik). It’s definitely worth a read. _And I reckon it’s worth implementing this approach in Aztec 3_.