Change the message to the same to improve BLS signature verification performance

[Kynea0b]

Summary

If the messages are the same, the messages are signed, and the messages are aggregated, the pairing map can be processed only once.

Problem Definition

Verification of aggregated BLS signatures is easy when the messages are the same, as shown in the following formula. By simplifying the verification, the pairing mapping only needs to be performed once, and the computational complexity can be significantly reduced.

reference:
https://crypto.stanford.edu/~dabo/pubs/papers/BLSmultisig.html#BGLS03

Therefore, it is necessary to change the message when signing to be the same.

Proposal

The message used when signing is this structure. If all the Timestamp are the same, the message when signing will be the same.

type CanonicalVote struct {
	Type      SignedMsgType // type alias for byte
	Height    int64         `binary:"fixed64"`
	Round     int64         `binary:"fixed64"`
	BlockID   CanonicalBlockID
	Timestamp time.Time
	ChainID   string
}

Then we call this function to verify.
https://github.com/herumi/bls-eth-go-binary/blob/master/bls/bls.go#L843

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related issue

#72

see also by tendermint/tendermint:

https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-025-commit.md#decision
tendermint/tendermint#2840 (comment)

For Admin Use

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

[Kynea0b]

What is the purpose of BLS aggregate signatures?

The BLS aggregate signature is one of the important solutions to the scalability problem associated with the IBC

What is required for BLS aggregate signature to work well ?

In this issue, the desirable Vote data design for the use of BLS aggregate signatures is being considered.
tendermint/tendermint#2840 (comment)

How timestamp was introduced to vote?

In this issue, vote timestamp is introduced as BFT time.
Since it is used as a value to protect security in view of IBC extension, it is necessary to reconsider a mechanism to replace it in order to utilize BLS. See this for details.
tendermint/tendermint#2013
tendermint/tendermint#1146

[tac0turtle]

Here is what tendermint/tendermint will use to get to BLS aggregation

tendermint/tendermint#6942

[Kynea0b]

Since the BLS sig has been removed, this issue is also closed.
#541