Signature verification efforts

[blasrodri]

This issue compiles the short-term journey for the R&D (math-focused) team.

• Study, give benchmarks and propose optimizations for https://github.com/privacy-scaling-explorations/halo2wrong/blob/master/ecdsa/ (please confirm if this is the one we are checking out)

In particular:

1. Give pen + paper understanding of the topology of the circuit: number of constraints + on-chain costs (call data + proving times?)
2. Assess room for improvement
3. Compare to alternative implementation/frameworks (gnark/circom?)

[blasrodri]

@seunlanlege please feel free to update this

[seunlanlege]

I already said this on the sync call but halo2 is our only option.

There are benchmarks that show halo2 has faster proving/verification times than circom.

I also said that the EF is at the forefront of zero knowledge research.

Here's a PR to gnark adding support for ECDSA showing that they're using the EF's research Consensys/gnark#372