fix: broadcast message with aggregated key

[RiXelanya]

Description

I tried to make a new broadcast which includes the aggregate signature and public keys

Related issue(s)

If this Pull Request is related to an issue, mention it here.

• Fixes Hello message should contains all public keys #547

[amirvalhalla]

@RiXelanya
please follow the PR title rules. read more:
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[b00f]

@RiXelanya

From your PR, I can see that you got a little bit confused. I believe the main reason for this confusion is the need to maintain backward compatibility. It's okay, no problem. I'll try to explain it a little more here.

sayHelloLagacy method

I suggest renaming the sayHello function to sayHelloLegacy and keeping it as it is. Please make sure to apply this change to the tests as well, so that they remain functional.

The sayHelloLegacy method helps us maintain backward compatibility, but we don't need to keep it forever. In a future release, once we confirm that the majority of the nodes are supporting the new format, we can safely delete it.

Adding comments to the code would be a good idea to provide clarity and context.

sayHello method

Now we can implement sayHello, In this method first we can get the list of all public keys from the sync.signers and at the same time we calculate the aggregated signature.

Probably should be something like this:

pubs := make([]*bls.PublicKey, 0, len(sync.signers))
sigs := make([]*bls.Signature, 0, len(sync.signers))

for _, signer := range sync.signers {
	signer.SignMsg(msg)
	pubs = append(pubkeys, msg.PublicKey)
	sigs = append(signs, msg.Signature)
}
aggSig := bls.SignatureAggregate(signs)

Now, we have the aggregated signature (only one signature) and list of all public keys.
Let's create another hello message and broadcast it.

msg.Signature = aggSig
msg.PublicKeys = pubs
msg.PublicKey = nil

Signature Verification

Now, let's move to the verification part. It is done inside the SanityCheck function.
Here, we need to support both Legacy and new format.

How to figure out? It is easy. If PulicKey set, it is legacy version, it PubliKeys set it is new version.
So we will have something like:

func (m *HelloMessage) SanityCheck() error {
	if m.Signature == nil {
		return errors.Error(errors.ErrInvalidSignature)
	}
	if m.PublicKey == nil &&  m.PublicKeys == nil {
		return errors.Error(errors.ErrInvalidPublicKey)
	}
	if m.PublicKey != nil {
             /// Legacy version
             return m.PublicKey.Verify(m.SignBytes(), m.Signature)
	} else {
	/// 1- Calculate the Aggregated Public key
	/// 2- Verify the signature
        }
}

[RiXelanya]

Understood. I will start fixing it now. apologies for the late response. I was busy yesterday

[themantre]

Fixed at #640