drand / kyber-bls12381

Kyber wrapper around kilic/bls12381 library

kyber-bls12381

Kyber wrapper around kilic/bls12381 library.

Note: GT does not fully support the kyber.Point interface yet.

Previous library

This repository is the successor of the previous library bls12381 which was a complete fork of the upstream library.

kyber-bls12381's Issues

upgrade github.com/kilic/bls12-381 version ？

cur github.com/kilic/bls12-381 v0.0.0-20200820230200-6b2c19996391

Can it support github.com/kilic/bls12-381 v0.1.0 ?

print /data/user/mods/pkg/mod/github.com/drand/[email protected]/kyber_g1.go:92:50: cannot use &s.(*mod.Int).V (type *big.Int) as type *bls12381.Fr in argument to bls12381.NewG1().MulScalar /data/user/mods/pkg/mod/github.com/drand/[email protected]/kyber_g2.go:97:50: cannot use &s.(*mod.Int).V (type *big.Int) as type *bls12381.Fr in argument to bls12381.NewG2().MulScalar when i exec go build

I found that it was a problem with the github.com/kilic/bls12-381 version！

`go generate` compatibility.dat

see 01c4331#r39752400

Are there plans to open source this code?

I noticed that this repo has no LICENSE file, while all other parts of drand are open source. Is this on purpose? If so, are there plans to change at some point?

The same Domain is used for both G1 and G2 Hash()

It appears that we are currently re-using the same domain for both G1 and G2 hash to curve functions:

kyber-bls12381/kyber_g1.go

Lines 135 to 140 in 21249c0

	func (k *KyberG1) Hash(m []byte) kyber.Point {
	p, _ := bls12381.NewG1().HashToCurve(m, Domain)
	k.p = p
	return k
	}

kyber-bls12381/kyber_g2.go

Lines 140 to 144 in 21249c0

	func (k *KyberG2) Hash(m []byte) kyber.Point {
	pg2, _ := bls12381.NewG2().HashToCurve(m, Domain)
	k.p = pg2
	return k
	}

with Domain being:

kyber-bls12381/kyber_g2.go

Lines 14 to 16 in 21249c0

	// Domain comes from the ciphersuite used by the RFC of this name compatible
	// with the paired library > v18
	var Domain = []byte("BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_NUL_")

This is unfortunate as it makes us non-spec compliant 😢
Security-wise it shouldn't be an issue as long as we are not re-using the same secret on both G1 and G2.

Use newer kilic library with Fr

Fr has been introduced now in kilic/ and we should switch to it instead of using our own big.Int wrapper for G1 G2 operations.