plugeth/crypto/kzg4844/kzg4844.go
Felix Lange 0e93da3197
crypto/kzg4844: add helpers for versioned blob hashes (#28827)
The code to compute a versioned hash was duplicated a couple times, and also had a small
issue: if we ever change params.BlobTxHashVersion, it will most likely also cause changes
to the actual hash computation. So it's a bit useless to have this constant in params.
2024-01-19 11:41:17 +01:00

130 lines
4.1 KiB
Go

// Copyright 2023 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Package kzg4844 implements the KZG crypto for EIP-4844.
package kzg4844
import (
"embed"
"errors"
"hash"
"sync/atomic"
)
//go:embed trusted_setup.json
var content embed.FS
// Blob represents a 4844 data blob.
type Blob [131072]byte
// Commitment is a serialized commitment to a polynomial.
type Commitment [48]byte
// Proof is a serialized commitment to the quotient polynomial.
type Proof [48]byte
// Point is a BLS field element.
type Point [32]byte
// Claim is a claimed evaluation value in a specific point.
type Claim [32]byte
// useCKZG controls whether the cryptography should use the Go or C backend.
var useCKZG atomic.Bool
// UseCKZG can be called to switch the default Go implementation of KZG to the C
// library if fo some reason the user wishes to do so (e.g. consensus bug in one
// or the other).
func UseCKZG(use bool) error {
if use && !ckzgAvailable {
return errors.New("CKZG unavailable on your platform")
}
useCKZG.Store(use)
// Initializing the library can take 2-4 seconds - and can potentially crash
// on CKZG and non-ADX CPUs - so might as well do it now and don't wait until
// a crypto operation is actually needed live.
if use {
ckzgIniter.Do(ckzgInit)
} else {
gokzgIniter.Do(gokzgInit)
}
return nil
}
// BlobToCommitment creates a small commitment out of a data blob.
func BlobToCommitment(blob Blob) (Commitment, error) {
if useCKZG.Load() {
return ckzgBlobToCommitment(blob)
}
return gokzgBlobToCommitment(blob)
}
// ComputeProof computes the KZG proof at the given point for the polynomial
// represented by the blob.
func ComputeProof(blob Blob, point Point) (Proof, Claim, error) {
if useCKZG.Load() {
return ckzgComputeProof(blob, point)
}
return gokzgComputeProof(blob, point)
}
// VerifyProof verifies the KZG proof that the polynomial represented by the blob
// evaluated at the given point is the claimed value.
func VerifyProof(commitment Commitment, point Point, claim Claim, proof Proof) error {
if useCKZG.Load() {
return ckzgVerifyProof(commitment, point, claim, proof)
}
return gokzgVerifyProof(commitment, point, claim, proof)
}
// ComputeBlobProof returns the KZG proof that is used to verify the blob against
// the commitment.
//
// This method does not verify that the commitment is correct with respect to blob.
func ComputeBlobProof(blob Blob, commitment Commitment) (Proof, error) {
if useCKZG.Load() {
return ckzgComputeBlobProof(blob, commitment)
}
return gokzgComputeBlobProof(blob, commitment)
}
// VerifyBlobProof verifies that the blob data corresponds to the provided commitment.
func VerifyBlobProof(blob Blob, commitment Commitment, proof Proof) error {
if useCKZG.Load() {
return ckzgVerifyBlobProof(blob, commitment, proof)
}
return gokzgVerifyBlobProof(blob, commitment, proof)
}
// CalcBlobHashV1 calculates the 'versioned blob hash' of a commitment.
// The given hasher must be a sha256 hash instance, otherwise the result will be invalid!
func CalcBlobHashV1(hasher hash.Hash, commit *Commitment) (vh [32]byte) {
if hasher.Size() != 32 {
panic("wrong hash size")
}
hasher.Reset()
hasher.Write(commit[:])
hasher.Sum(vh[:0])
vh[0] = 0x01 // version
return vh
}
// IsValidVersionedHash checks that h is a structurally-valid versioned blob hash.
func IsValidVersionedHash(h []byte) bool {
return len(h) == 32 && h[0] == 0x01
}