Aggregate public keys

[Kynea0b]

Ref #204

Summary

Computational complexity is less when public keys are aggregated at the time of aggregation signature creation rather than at verification.

Problem Definition

If you sign the same message and aggregate the signatures, use this function for verification.
https://github.com/herumi/bls-eth-go-binary/blob/master/bls/bls.go#L843
However, this internally aggregates the public key array for each verification. This takes time, so if you aggregate the public keys when creating the aggregate signature and use that key, we only need to aggregate the keys once.

Proposal

We can use this function to aggregate public keys
https://github.com/herumi/bls-eth-go-binary/blob/master/bls/bls.go#L461

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned