BLS Components for Simplex

[samliok]

Why this should be merged

Introduces BLSSigner and BLSVerifier in the new simplex package for signing and verifying messages (e.g., votes) in Simplex consensus. BLSVerifier will be extended in future PRs to support quorum certificate verification and additional functionality.

The newly created Config struct is provided during simplex engine initialization and contains only the fields necessary for the current functionality of the simplex package.

How this works

In future PRs, the simplex package will be expanded to integrate simplex into AvalancheGo.

How this was tested

Add unit tests in bls_test.go

Need to be documented in RELEASES.md?

No

[Copilot]

Pull Request Overview

Adds BLS signing and verification to the new simplex package by defining configuration, signer/verifier types, and tests.

• Introduces Config, ValidatorInfo, and SimplexChainContext for engine setup
• Implements BLSSigner/BLSVerifier with ASN.1–encoded messages
• Provides unit tests in bls_test.go and updates go.mod for local module replacement

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
simplex/config.go	Define Config, ValidatorInfo, and chain context
simplex/bls.go	Implement BLS signer/verifier and message encoding
simplex/bls_test.go	Add tests for signing, valid/invalid signer and messages
go.mod	Add replace directive for simplex module

Comments suppressed due to low confidence (1)

simplex/bls.go:23

• The comment refers to 'NetworkID' but the field is named SubnetID. Update the comment to avoid confusion.

// BLSSigner signs messages encoded with the provided ChainID and NetworkID

[yacovm]

What about the QC stuff? Is that a future PR?

[yacovm]

LGTM modulo two comments above

[samliok]

What about the QC stuff? Is that a future PR?

Yep!