# HeyAnoun x Spartan-ecdsa This doc consists of the possible way to use Spartan-ecdsa in HeyAnoun, and a general analysis of Spartan-ecdsa. ## A possbile way to use Spartna-ecdsa in HeyAnoun [Querying the tx counts of nouns tokens owners and delegates](https://dune.com/queries/2035869) on Dune, it seems like all of them have at least one tx submitted. But this could change (or my dune query isn’t 100% correct in the first place) so we’ll need to have a fallback mechanism when the prover’s pubkey isn’t available. Having separate Merkle trees for the address group and the pubkey group isn’t going to work because there will be only a few addresses (if any) that need to use the address group (when the prover uses the address group they’ll almost certainly dox themselves). So I think we’ll need to go for the “after adding your pubkey to the merkle tree, at least wait for 24h before submitting your first proof” idea, if we want to migrate to Spartan-ecdsa. ## Generalizing the above observation, and a general analysis of Spartan-ecdsa - Given the above observation that **even only with pubkey group membership proving, one can build a pseudonym app with a pretty good UX**, we can hypothesize: - **Spartan-ecdsa with on-chain verification is going to be sufficient for many pseudonyms apps** - Spartan-ecdsa, when compared to eff-zk-ecdsa - **Pros** - Faster proving! - Aligned with the roadmap (we’re focused on maintaining Spartan-ecdsa and not eff-zk-ecdsa) - **Cons** - **More likely to contain vulnerability when compared to eff-zk-ecdsa** - Spartan-ecdsa builds on code that has not been battle-tested such as Spartan and Halo2 on-chain verifier(WIP). This is in contrast to eff-zk-ecdsa which builds on top of the widely-used Circom. - [There was a commit](https://github.com/microsoft/Spartan/commit/1e431e2bbfe74b8a53488c43adf32de1dd974777) to the original Spartan repo that fixes a soundness bug, which we need to apply to Spartan-ecdsa soon. I inquired Srinath re this and waiting for his response. - Harder on-chain verification - Writing a Spartan verifier in Halo2 is non-trivial - Though it’s important to note that eff-zk-ecdsa w/ on-chain verification will come with additional cost on the prover!