Import Chainlink's Distributed Schnorr implementation
Unmodified except for imports and addition of license files.
This commit is contained in:
Leo
parent
71c0e29dcf
commit
2a81b445b1
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@ -3,8 +3,9 @@ module github.com/certusone/wormhole/bridge
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go 1.14
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require (
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github.com/btcsuite/btcd v0.20.1-beta
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github.com/cenkalti/backoff/v4 v4.0.2
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github.com/ipfs/go-log v1.0.4
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github.com/ethereum/go-ethereum v1.9.18
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github.com/ipfs/go-log/v2 v2.1.1
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github.com/libp2p/go-libp2p v0.10.2
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github.com/libp2p/go-libp2p-connmgr v0.2.4
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@ -14,6 +15,11 @@ require (
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github.com/libp2p/go-libp2p-quic-transport v0.7.1
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github.com/libp2p/go-libp2p-tls v0.1.3
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github.com/multiformats/go-multiaddr v0.2.2
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github.com/smartcontractkit/chainlink v0.8.11
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github.com/stretchr/testify v1.6.1
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go.dedis.ch/fixbuf v1.0.3
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go.dedis.ch/kyber/v3 v3.0.12
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go.uber.org/zap v1.15.0
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golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
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google.golang.org/grpc v1.31.0
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)
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@ -0,0 +1,21 @@
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The MIT License (MIT)
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Copyright (c) 2018 SmartContract ChainLink, Ltd.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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@ -0,0 +1,2 @@
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The Distributed Schnorr Signature Go implementation and the corresponding Solidity smart contract
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have been imported from https://hub.docker.com/r/smartcontract/chainlink (which is based ob EPFL DEDIS/kyber).
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@ -0,0 +1,304 @@
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// Package ethdss implements the Distributed Schnorr Signature protocol from the
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////////////////////////////////////////////////////////////////////////////////
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// XXX: Do not use in production until this code has been audited.
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////////////////////////////////////////////////////////////////////////////////
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// paper "Provably Secure Distributed Schnorr Signatures and a (t, n)
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// Threshold Scheme for Implicit Certificates".
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// https://dl.acm.org/citation.cfm?id=678297
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// To generate a distributed signature from a group of participants, the group
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// must first generate one longterm distributed secret with the share/dkg
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// package, and then one random secret to be used only once.
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// Each participant then creates a DSS struct, that can issue partial signatures
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// with `dss.PartialSignature()`. These partial signatures can be broadcasted to
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// the whole group or to a trusted combiner. Once one has collected enough
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// partial signatures, it is possible to compute the distributed signature with
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// the `Signature` method.
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//
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// This is mostly copied from the sign/dss package, with minor adjustments for
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// use with ethschnorr.
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package ethdss
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import (
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"bytes"
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"errors"
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"math/big"
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"go.dedis.ch/kyber/v3"
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"go.dedis.ch/kyber/v3/share"
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"github.com/certusone/wormhole/bridge/third_party/chainlink/ethschnorr"
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"github.com/certusone/wormhole/bridge/third_party/chainlink/secp256k1"
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)
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// Suite represents the functionalities needed by the dss package
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type Suite interface {
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kyber.Group
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kyber.HashFactory
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kyber.Random
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}
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var secp256k1Suite = secp256k1.NewBlakeKeccackSecp256k1()
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var secp256k1Group kyber.Group = secp256k1Suite
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// DistKeyShare is an abstraction to allow one to use distributed key share
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// from different schemes easily into this distributed threshold Schnorr
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// signature framework.
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type DistKeyShare interface {
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PriShare() *share.PriShare
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Commitments() []kyber.Point
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}
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// DSS holds the information used to issue partial signatures as well as to
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// compute the distributed schnorr signature.
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type DSS struct {
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// Keypair for this participant in the signing process (i.e., the one where
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// this struct is stored.) This is not the keypair for full signing key; that
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// would defeat the point.
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secret kyber.Scalar
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public kyber.Point
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// Index value of this participant in the signing process. The index is shared
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// across participants.
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index int
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// Public keys of potential participants in the signing process
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participants []kyber.Point
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// Number of participants needed to construct a signature
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T int
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// Shares of the distributed long-term signing keypair
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long DistKeyShare
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// Shares of the distributed ephemeral nonce keypair
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random DistKeyShare
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// Pedersen commitments to the coefficients of the polynomial implicitly used
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// to share the long-term signing public/private keypair.
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longPoly *share.PubPoly
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// Pedersen commitments to the coefficients of the polynomial implicitly used
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// to share the ephemeral nonce keypair.
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randomPoly *share.PubPoly
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// Message to be signed
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msg *big.Int
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// The partial signatures collected so far.
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partials []*share.PriShare
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// Indices for the participants who have provided their partial signatures to
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// this participant.
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partialsIdx map[int]bool
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// True iff the partial signature for this dss has been signed by its owner.
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signed bool
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// String which uniquely identifies this signature, shared by all
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// participants.
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sessionID []byte
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}
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// DSSArgs is the arguments to NewDSS, as a struct. See NewDSS for details.
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type DSSArgs = struct {
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secret kyber.Scalar
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participants []kyber.Point
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long DistKeyShare
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random DistKeyShare
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msg *big.Int
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T int
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}
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// PartialSig is partial representation of the final distributed signature. It
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// must be sent to each of the other participants.
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type PartialSig struct {
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Partial *share.PriShare
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SessionID []byte
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Signature ethschnorr.Signature
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}
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// NewDSS returns a DSS struct out of the suite, the longterm secret of this
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// node, the list of participants, the longterm and random distributed key
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// (generated by the dkg package), the message to sign and finally the T
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// threshold. It returns an error if the public key of the secret can't be found
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// in the list of participants.
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func NewDSS(args DSSArgs) (*DSS, error) {
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public := secp256k1Group.Point().Mul(args.secret, nil)
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var i int
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var found bool
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for j, p := range args.participants {
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if p.Equal(public) {
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found = true
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i = j
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break
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}
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}
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if !found {
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return nil, errors.New("dss: public key not found in list of participants")
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}
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return &DSS{
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secret: args.secret,
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public: public,
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index: i,
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participants: args.participants,
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long: args.long,
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longPoly: share.NewPubPoly(secp256k1Suite,
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secp256k1Group.Point().Base(), args.long.Commitments()),
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random: args.random,
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randomPoly: share.NewPubPoly(secp256k1Suite,
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secp256k1Group.Point().Base(), args.random.Commitments()),
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msg: args.msg,
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T: args.T,
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partialsIdx: make(map[int]bool),
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sessionID: sessionID(secp256k1Suite, args.long, args.random),
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}, nil
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}
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// PartialSig generates the partial signature related to this DSS. This
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// PartialSig can be broadcasted to every other participant or only to a
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// trusted combiner as described in the paper.
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// The signature format is compatible with EdDSA verification implementations.
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//
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// Corresponds to section 4.2, step 2 the Stinson 2001 paper.
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func (d *DSS) PartialSig() (*PartialSig, error) {
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secretPartialLongTermKey := d.long.PriShare().V // ɑᵢ, in the paper
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secretPartialCommitmentKey := d.random.PriShare().V // βᵢ, in the paper
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fullChallenge := d.hashSig() // h(m‖V), in the paper
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secretChallengeMultiple := secp256k1Suite.Scalar().Mul(
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fullChallenge, secretPartialLongTermKey) // ɑᵢh(m‖V)G, in the paper
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// Corresponds to ɣᵢG=βᵢG+ɑᵢh(m‖V)G in the paper, but NB, in its notation, we
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// use ɣᵢG=βᵢG-ɑᵢh(m‖V)G. (Subtract instead of add.)
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partialSignature := secp256k1Group.Scalar().Sub(
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secretPartialCommitmentKey, secretChallengeMultiple)
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ps := &PartialSig{
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Partial: &share.PriShare{V: partialSignature, I: d.index},
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SessionID: d.sessionID,
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}
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var err error
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ps.Signature, err = ethschnorr.Sign(d.secret, ps.Hash()) // sign share
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if !d.signed {
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d.partialsIdx[d.index] = true
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d.partials = append(d.partials, ps.Partial)
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d.signed = true
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}
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return ps, err
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}
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// ProcessPartialSig takes a PartialSig from another participant and stores it
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// for generating the distributed signature. It returns an error if the index is
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// wrong, or the signature is invalid or if a partial signature has already been
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// received by the same peer. To know whether the distributed signature can be
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// computed after this call, one can use the `EnoughPartialSigs` method.
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//
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// Corresponds to section 4.3, step 3 of the paper
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func (d *DSS) ProcessPartialSig(ps *PartialSig) error {
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var err error
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public, ok := findPub(d.participants, ps.Partial.I)
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if !ok {
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err = errors.New("dss: partial signature with invalid index")
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}
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// nothing secret here
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if err == nil && !bytes.Equal(ps.SessionID, d.sessionID) {
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err = errors.New("dss: session id do not match")
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}
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if err == nil {
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if vrr := ethschnorr.Verify(public, ps.Hash(), ps.Signature); vrr != nil {
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err = vrr
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}
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}
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if err == nil {
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if _, ok := d.partialsIdx[ps.Partial.I]; ok {
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err = errors.New("dss: partial signature already received from peer")
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}
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}
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if err != nil {
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return err
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}
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hash := d.hashSig() // h(m‖V), in the paper's notation
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idx := ps.Partial.I
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// βᵢG=sum(cₖi^kG), in the paper, defined as sᵢ in step 2 of section 2.4
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randShare := d.randomPoly.Eval(idx)
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// ɑᵢG=sum(bₖi^kG), defined as sᵢ in step 2 of section 2.4
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longShare := d.longPoly.Eval(idx)
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// h(m‖V)(Y+...) term from equation (3) of the paper. AKA h(m‖V)ɑᵢG
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challengeSummand := secp256k1Group.Point().Mul(hash, longShare.V)
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// RHS of equation (3), except we subtract the second term instead of adding.
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// AKA (βᵢ-ɑᵢh(m‖V))G, which should equal ɣᵢG, according to equation (3)
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maybePartialSigCommitment := secp256k1Group.Point().Sub(randShare.V,
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challengeSummand)
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// Check that equation (3) holds (ɣᵢ is represented as ps.Partial.V, here.)
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partialSigCommitment := secp256k1Group.Point().Mul(ps.Partial.V, nil)
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if !partialSigCommitment.Equal(maybePartialSigCommitment) {
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return errors.New("dss: partial signature not valid")
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}
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d.partialsIdx[ps.Partial.I] = true
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d.partials = append(d.partials, ps.Partial)
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return nil
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}
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// EnoughPartialSig returns true if there are enough partial signature to compute
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// the distributed signature. It returns false otherwise. If there are enough
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// partial signatures, one can issue the signature with `Signature()`.
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func (d *DSS) EnoughPartialSig() bool {
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return len(d.partials) >= d.T
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}
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// Signature computes the distributed signature from the list of partial
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// signatures received. It returns an error if there are not enough partial
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// signatures.
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//
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// Corresponds to section 4.2, step 4 of Stinson, 2001 paper
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func (d *DSS) Signature() (ethschnorr.Signature, error) {
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if !d.EnoughPartialSig() {
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return nil, errors.New("dkg: not enough partial signatures to sign")
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}
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// signature corresponds to σ in step 4 of section 4.2
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signature, err := share.RecoverSecret(secp256k1Suite, d.partials, d.T,
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len(d.participants))
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if err != nil {
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return nil, err
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}
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rv := ethschnorr.NewSignature()
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rv.Signature = secp256k1.ToInt(signature)
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// commitmentPublicKey corresponds to V in step 4 of section 4.2
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commitmentPublicKey := d.random.Commitments()[0]
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rv.CommitmentPublicAddress = secp256k1.EthereumAddress(commitmentPublicKey)
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return rv, nil
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}
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// hashSig returns, in the paper's notation, h(m‖V). It is the challenge hash
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// for the signature. (Actually, the hash also includes the public key, but that
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// has no effect on the correctness or robustness arguments from the paper.)
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func (d *DSS) hashSig() kyber.Scalar {
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v := d.random.Commitments()[0] // Public-key commitment, in signature from d
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vAddress := secp256k1.EthereumAddress(v)
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publicKey := d.long.Commitments()[0]
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rv, err := ethschnorr.ChallengeHash(publicKey, vAddress, d.msg)
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if err != nil {
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panic(err)
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}
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return rv
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}
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// Verify takes a public key, a message and a signature and returns an error if
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// the signature is invalid.
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func Verify(public kyber.Point, msg *big.Int, sig ethschnorr.Signature) error {
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return ethschnorr.Verify(public, msg, sig)
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}
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// Hash returns the hash representation of this PartialSig to be used in a
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// signature.
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func (ps *PartialSig) Hash() *big.Int {
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h := secp256k1Suite.Hash()
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_, _ = h.Write(ps.Partial.Hash(secp256k1Suite))
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_, _ = h.Write(ps.SessionID)
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return (&big.Int{}).SetBytes(h.Sum(nil))
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}
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func findPub(list []kyber.Point, i int) (kyber.Point, bool) {
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if i >= len(list) {
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return nil, false
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}
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return list[i], true
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}
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func sessionID(s Suite, a, b DistKeyShare) []byte {
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h := s.Hash()
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for _, p := range a.Commitments() {
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_, _ = p.MarshalTo(h)
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}
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for _, p := range b.Commitments() {
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_, _ = p.MarshalTo(h)
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}
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return h.Sum(nil)
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}
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@ -0,0 +1,290 @@
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package ethdss
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import (
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"crypto/rand"
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"fmt"
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"math/big"
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"testing"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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"github.com/smartcontractkit/chainlink/core/services/signatures/cryptotest"
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"github.com/smartcontractkit/chainlink/core/services/signatures/ethschnorr"
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"github.com/smartcontractkit/chainlink/core/services/signatures/secp256k1"
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"go.dedis.ch/kyber/v3"
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dkg "go.dedis.ch/kyber/v3/share/dkg/rabin"
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)
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var suite = secp256k1.NewBlakeKeccackSecp256k1()
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var nbParticipants = 7
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var t = nbParticipants/2 + 1
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var partPubs []kyber.Point
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var partSec []kyber.Scalar
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var longterms []*dkg.DistKeyShare
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var randoms []*dkg.DistKeyShare
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var msg *big.Int
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var randomStream = cryptotest.NewStream(&testing.T{}, 0)
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func init() {
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partPubs = make([]kyber.Point, nbParticipants)
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partSec = make([]kyber.Scalar, nbParticipants)
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for i := 0; i < nbParticipants; i++ {
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kp := secp256k1.Generate(randomStream)
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partPubs[i] = kp.Public
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partSec[i] = kp.Private
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}
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// Corresponds to section 4.2, step 1 of Stinson, 2001 paper
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longterms = genDistSecret(true) // Keep trying until valid public key
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randoms = genDistSecret(false)
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var err error
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msg, err = rand.Int(rand.Reader, big.NewInt(0).Lsh(big.NewInt(1), 256))
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if err != nil {
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panic(err)
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}
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}
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func TestDSSNew(t *testing.T) {
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dssArgs := DSSArgs{secret: partSec[0], participants: partPubs,
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long: longterms[0], random: randoms[0], msg: msg, T: 4}
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dss, err := NewDSS(dssArgs)
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assert.NotNil(t, dss)
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assert.Nil(t, err)
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dssArgs.secret = suite.Scalar().Zero()
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dss, err = NewDSS(dssArgs)
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assert.Nil(t, dss)
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assert.Error(t, err)
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}
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func TestDSSPartialSigs(t *testing.T) {
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dss0 := getDSS(0)
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dss1 := getDSS(1)
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ps0, err := dss0.PartialSig()
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assert.Nil(t, err)
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assert.NotNil(t, ps0)
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assert.Len(t, dss0.partials, 1)
|
||||
// second time should not affect list
|
||||
ps0, err = dss0.PartialSig()
|
||||
assert.Nil(t, err)
|
||||
assert.NotNil(t, ps0)
|
||||
assert.Len(t, dss0.partials, 1)
|
||||
|
||||
// wrong index
|
||||
goodI := ps0.Partial.I
|
||||
ps0.Partial.I = 100
|
||||
err = dss1.ProcessPartialSig(ps0)
|
||||
assert.Error(t, err)
|
||||
assert.Contains(t, err.Error(), "invalid index")
|
||||
ps0.Partial.I = goodI
|
||||
|
||||
// wrong sessionID
|
||||
goodSessionID := ps0.SessionID
|
||||
ps0.SessionID = []byte("ahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh")
|
||||
err = dss1.ProcessPartialSig(ps0)
|
||||
assert.Error(t, err)
|
||||
assert.Contains(t, err.Error(), "dss: session id")
|
||||
ps0.SessionID = goodSessionID
|
||||
|
||||
// wrong Signature
|
||||
goodSig := ps0.Signature
|
||||
ps0.Signature = ethschnorr.NewSignature()
|
||||
copy(ps0.Signature.CommitmentPublicAddress[:], randomBytes(20))
|
||||
badSig := secp256k1.ToInt(suite.Scalar().Pick(randomStream))
|
||||
ps0.Signature.Signature.Set(badSig)
|
||||
assert.Error(t, dss1.ProcessPartialSig(ps0))
|
||||
ps0.Signature = goodSig
|
||||
|
||||
// invalid partial sig
|
||||
goodV := ps0.Partial.V
|
||||
ps0.Partial.V = suite.Scalar().Zero()
|
||||
ps0.Signature, err = ethschnorr.Sign(dss0.secret, ps0.Hash())
|
||||
require.Nil(t, err)
|
||||
err = dss1.ProcessPartialSig(ps0)
|
||||
assert.Error(t, err)
|
||||
assert.Contains(t, err.Error(), "not valid")
|
||||
ps0.Partial.V = goodV
|
||||
ps0.Signature = goodSig
|
||||
|
||||
// fine
|
||||
err = dss1.ProcessPartialSig(ps0)
|
||||
assert.Nil(t, err)
|
||||
|
||||
// already received
|
||||
assert.Error(t, dss1.ProcessPartialSig(ps0))
|
||||
|
||||
// if not enough partial signatures, can't generate signature
|
||||
sig, err := dss1.Signature()
|
||||
assert.Nil(t, sig) // XXX: Should also check err is nil?
|
||||
assert.Error(t, err)
|
||||
assert.Contains(t, err.Error(), "not enough")
|
||||
|
||||
// enough partial sigs ?
|
||||
for i := 2; i < nbParticipants; i++ {
|
||||
dss := getDSS(i)
|
||||
ps, e := dss.PartialSig()
|
||||
require.Nil(t, e)
|
||||
require.Nil(t, dss1.ProcessPartialSig(ps))
|
||||
}
|
||||
assert.True(t, dss1.EnoughPartialSig())
|
||||
sig, err = dss1.Signature()
|
||||
assert.NoError(t, err)
|
||||
assert.NoError(t, Verify(dss1.long.Commitments()[0], msg, sig))
|
||||
}
|
||||
|
||||
var printTests = false
|
||||
|
||||
func printTest(t *testing.T, msg *big.Int, public kyber.Point,
|
||||
signature ethschnorr.Signature) {
|
||||
pX, pY := secp256k1.Coordinates(public)
|
||||
fmt.Printf(" ['%064x',\n '%064x',\n '%064x',\n '%064x',\n '%040x'],\n",
|
||||
msg, pX, pY, signature.Signature,
|
||||
signature.CommitmentPublicAddress)
|
||||
}
|
||||
|
||||
func TestDSSSignature(t *testing.T) {
|
||||
dsss := make([]*DSS, nbParticipants)
|
||||
pss := make([]*PartialSig, nbParticipants)
|
||||
for i := 0; i < nbParticipants; i++ {
|
||||
dsss[i] = getDSS(i)
|
||||
ps, err := dsss[i].PartialSig()
|
||||
require.Nil(t, err)
|
||||
require.NotNil(t, ps)
|
||||
pss[i] = ps
|
||||
}
|
||||
for i, dss := range dsss {
|
||||
for j, ps := range pss {
|
||||
if i == j {
|
||||
continue
|
||||
}
|
||||
require.Nil(t, dss.ProcessPartialSig(ps))
|
||||
}
|
||||
}
|
||||
// issue and verify signature
|
||||
dss0 := dsss[0]
|
||||
sig, err := dss0.Signature()
|
||||
assert.NotNil(t, sig)
|
||||
assert.Nil(t, err)
|
||||
assert.NoError(t, ethschnorr.Verify(longterms[0].Public(), dss0.msg, sig))
|
||||
// Original contains this second check. Unclear why.
|
||||
assert.NoError(t, ethschnorr.Verify(longterms[0].Public(), dss0.msg, sig))
|
||||
if printTests {
|
||||
printTest(t, dss0.msg, dss0.long.Commitments()[0], sig)
|
||||
}
|
||||
}
|
||||
|
||||
func TestPartialSig_Hash(t *testing.T) {
|
||||
observedHashes := make(map[*big.Int]bool)
|
||||
for i := 0; i < nbParticipants; i++ {
|
||||
psig, err := getDSS(i).PartialSig()
|
||||
require.NoError(t, err)
|
||||
hash := psig.Hash()
|
||||
require.False(t, observedHashes[hash])
|
||||
observedHashes[hash] = true
|
||||
}
|
||||
}
|
||||
|
||||
func getDSS(i int) *DSS {
|
||||
dss, err := NewDSS(DSSArgs{secret: partSec[i], participants: partPubs,
|
||||
long: longterms[i], random: randoms[i], msg: msg, T: t})
|
||||
if dss == nil || err != nil {
|
||||
panic("nil dss")
|
||||
}
|
||||
return dss
|
||||
}
|
||||
|
||||
func _genDistSecret() []*dkg.DistKeyShare {
|
||||
dkgs := make([]*dkg.DistKeyGenerator, nbParticipants)
|
||||
for i := 0; i < nbParticipants; i++ {
|
||||
dkg, err := dkg.NewDistKeyGenerator(suite, partSec[i], partPubs, nbParticipants/2+1)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
dkgs[i] = dkg
|
||||
}
|
||||
// full secret sharing exchange
|
||||
// 1. broadcast deals
|
||||
resps := make([]*dkg.Response, 0, nbParticipants*nbParticipants)
|
||||
for _, dkg := range dkgs {
|
||||
deals, err := dkg.Deals()
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
for i, d := range deals {
|
||||
resp, err := dkgs[i].ProcessDeal(d)
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
if !resp.Response.Approved {
|
||||
panic("wrong approval")
|
||||
}
|
||||
resps = append(resps, resp)
|
||||
}
|
||||
}
|
||||
// 2. Broadcast responses
|
||||
for _, resp := range resps {
|
||||
for h, dkg := range dkgs {
|
||||
// ignore all messages from ourself
|
||||
if resp.Response.Index == uint32(h) {
|
||||
continue
|
||||
}
|
||||
j, err := dkg.ProcessResponse(resp)
|
||||
if err != nil || j != nil {
|
||||
panic("wrongProcessResponse")
|
||||
}
|
||||
}
|
||||
}
|
||||
// 4. Broadcast secret commitment
|
||||
for i, dkg := range dkgs {
|
||||
scs, err := dkg.SecretCommits()
|
||||
if err != nil {
|
||||
panic("wrong SecretCommits")
|
||||
}
|
||||
for j, dkg2 := range dkgs {
|
||||
if i == j {
|
||||
continue
|
||||
}
|
||||
cc, err := dkg2.ProcessSecretCommits(scs)
|
||||
if err != nil || cc != nil {
|
||||
panic("wrong ProcessSecretCommits")
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// 5. reveal shares
|
||||
dkss := make([]*dkg.DistKeyShare, len(dkgs))
|
||||
for i, dkg := range dkgs {
|
||||
dks, err := dkg.DistKeyShare()
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
dkss[i] = dks
|
||||
}
|
||||
return dkss
|
||||
|
||||
}
|
||||
|
||||
func genDistSecret(checkValidPublicKey bool) []*dkg.DistKeyShare {
|
||||
rv := _genDistSecret()
|
||||
if checkValidPublicKey {
|
||||
// Because of the trick we're using to verify the signatures on-chain, we
|
||||
// need to make sure that the ordinate of this distributed public key is
|
||||
// in the lower half of {0,...,}
|
||||
for !secp256k1.ValidPublicKey(rv[0].Public()) {
|
||||
rv = _genDistSecret() // Keep trying until valid distributed public key.
|
||||
}
|
||||
}
|
||||
return rv
|
||||
}
|
||||
|
||||
func randomBytes(n int) []byte {
|
||||
var buff = make([]byte, n)
|
||||
_, _ = rand.Read(buff[:])
|
||||
return buff
|
||||
}
|
||||
|
|
@ -0,0 +1,152 @@
|
|||
// Package ethschnorr implements a version of the Schnorr signature which is
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// XXX: Do not use in production until this code has been audited.
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// cheap to verify on-chain.
|
||||
//
|
||||
// See https://en.wikipedia.org/wiki/Schnorr_signature For vanilla Schnorr.
|
||||
//
|
||||
// Since we are targeting ethereum specifically, there is no need to abstract
|
||||
// away the group operations, as original kyber Schnorr code does. Thus, these
|
||||
// functions only work with secp256k1 objects, even though they are expressed in
|
||||
// terms of the abstract kyber Group interfaces.
|
||||
//
|
||||
// This code is largely based on EPFL-DEDIS's go.dedis.ch/kyber/sign/schnorr
|
||||
package ethschnorr
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"math/big"
|
||||
|
||||
"go.dedis.ch/kyber/v3"
|
||||
|
||||
"github.com/certusone/wormhole/bridge/third_party/chainlink/secp256k1"
|
||||
)
|
||||
|
||||
var secp256k1Suite = secp256k1.NewBlakeKeccackSecp256k1()
|
||||
var secp256k1Group kyber.Group = secp256k1Suite
|
||||
|
||||
type signature = struct {
|
||||
CommitmentPublicAddress [20]byte
|
||||
Signature *big.Int
|
||||
}
|
||||
|
||||
// Signature is a representation of the Schnorr signature generated and verified
|
||||
// by this library.
|
||||
type Signature = *signature
|
||||
|
||||
func i() *big.Int { return big.NewInt(0) }
|
||||
|
||||
var one = big.NewInt(1)
|
||||
var u256Cardinality = i().Lsh(one, 256)
|
||||
var maxUint256 = i().Sub(u256Cardinality, one)
|
||||
|
||||
// NewSignature allocates space for a Signature, and returns it
|
||||
func NewSignature() Signature { return &signature{Signature: i()} }
|
||||
|
||||
var zero = i()
|
||||
|
||||
// ValidSignature(s) is true iff s.Signature represents an element of secp256k1
|
||||
func ValidSignature(s Signature) bool {
|
||||
return s.Signature.Cmp(secp256k1.GroupOrder) == -1 &&
|
||||
s.Signature.Cmp(zero) != -1
|
||||
}
|
||||
|
||||
// ChallengeHash returns the value the signer must use to demonstrate knowledge
|
||||
// of the secret key
|
||||
//
|
||||
// NB: for parity with the on-chain hash, it's important that public and r
|
||||
// marshall to the big-endian x ordinate, followed by a byte which is 0 if the y
|
||||
// ordinate is even, 1 if it's odd. See evm/contracts/SchnorrSECP256K1.sol and
|
||||
// evm/test/schnorr_test.js
|
||||
func ChallengeHash(public kyber.Point, rAddress [20]byte, msg *big.Int) (
|
||||
kyber.Scalar, error) {
|
||||
var err error
|
||||
h := secp256k1Suite.Hash()
|
||||
if _, herr := public.MarshalTo(h); herr != nil {
|
||||
err = fmt.Errorf("failed to hash public key for signature: %s", herr)
|
||||
}
|
||||
if err != nil && (msg.BitLen() > 256 || msg.Cmp(zero) == -1) {
|
||||
err = fmt.Errorf("msg must be a uint256")
|
||||
}
|
||||
if err == nil {
|
||||
if _, herr := h.Write(msg.Bytes()); herr != nil {
|
||||
err = fmt.Errorf("failed to hash message for signature: %s", herr)
|
||||
}
|
||||
}
|
||||
if err == nil {
|
||||
if _, herr := h.Write(rAddress[:]); herr != nil {
|
||||
err = fmt.Errorf("failed to hash r for signature: %s", herr)
|
||||
}
|
||||
}
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
return secp256k1Suite.Scalar().SetBytes(h.Sum(nil)), nil
|
||||
}
|
||||
|
||||
// Sign creates a signature from a msg and a private key. Verify with the
|
||||
// function Verify, or on-chain with SchnorrSECP256K1.sol.
|
||||
func Sign(private kyber.Scalar, msg *big.Int) (Signature, error) {
|
||||
if !secp256k1.IsSecp256k1Scalar(private) {
|
||||
return nil, fmt.Errorf("private key is not a secp256k1 scalar")
|
||||
}
|
||||
// create random secret and public commitment to it
|
||||
commitmentSecretKey := secp256k1Group.Scalar().Pick(
|
||||
secp256k1Suite.RandomStream())
|
||||
commitmentPublicKey := secp256k1Group.Point().Mul(commitmentSecretKey, nil)
|
||||
commitmentPublicAddress := secp256k1.EthereumAddress(commitmentPublicKey)
|
||||
|
||||
public := secp256k1Group.Point().Mul(private, nil)
|
||||
challenge, err := ChallengeHash(public, commitmentPublicAddress, msg)
|
||||
if err != nil {
|
||||
return nil, err
|
||||
}
|
||||
// commitmentSecretKey-private*challenge
|
||||
s := secp256k1Group.Scalar().Sub(commitmentSecretKey,
|
||||
secp256k1Group.Scalar().Mul(private, challenge))
|
||||
rv := signature{commitmentPublicAddress, secp256k1.ToInt(s)}
|
||||
return &rv, nil
|
||||
}
|
||||
|
||||
// Verify verifies the given Schnorr signature. It returns true iff the
|
||||
// signature is valid.
|
||||
func Verify(public kyber.Point, msg *big.Int, s Signature) error {
|
||||
var err error
|
||||
if !ValidSignature(s) {
|
||||
err = fmt.Errorf("s is not a valid signature")
|
||||
}
|
||||
if err == nil && !secp256k1.IsSecp256k1Point(public) {
|
||||
err = fmt.Errorf("public key is not a secp256k1 point")
|
||||
}
|
||||
if err == nil && !secp256k1.ValidPublicKey(public) {
|
||||
err = fmt.Errorf("`public` is not a valid public key")
|
||||
}
|
||||
if err == nil && (msg.Cmp(zero) == -1 || msg.Cmp(maxUint256) == 1) {
|
||||
err = fmt.Errorf("msg is not a uint256")
|
||||
}
|
||||
var challenge kyber.Scalar
|
||||
var herr error
|
||||
if err == nil {
|
||||
challenge, herr = ChallengeHash(public, s.CommitmentPublicAddress, msg)
|
||||
if herr != nil {
|
||||
err = herr
|
||||
}
|
||||
}
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
sigScalar := secp256k1.IntToScalar(s.Signature)
|
||||
// s*g + challenge*public = s*g + challenge*(secretKey*g) =
|
||||
// commitmentSecretKey*g = commitmentPublicKey
|
||||
maybeCommitmentPublicKey := secp256k1Group.Point().Add(
|
||||
secp256k1Group.Point().Mul(sigScalar, nil),
|
||||
secp256k1Group.Point().Mul(challenge, public))
|
||||
maybeCommitmentPublicAddress := secp256k1.EthereumAddress(maybeCommitmentPublicKey)
|
||||
if !bytes.Equal(s.CommitmentPublicAddress[:],
|
||||
maybeCommitmentPublicAddress[:]) {
|
||||
return fmt.Errorf("signature mismatch")
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
|
@ -0,0 +1,114 @@
|
|||
package ethschnorr
|
||||
|
||||
// This code is largely based on go.dedis.ch/kyber/sign/schnorr_test from
|
||||
// EPFL's DEDIS
|
||||
|
||||
import (
|
||||
crand "crypto/rand"
|
||||
"fmt"
|
||||
"math/big"
|
||||
mrand "math/rand"
|
||||
"testing"
|
||||
|
||||
"github.com/smartcontractkit/chainlink/core/services/signatures/cryptotest"
|
||||
"github.com/stretchr/testify/require"
|
||||
|
||||
"go.dedis.ch/kyber/v3"
|
||||
"go.dedis.ch/kyber/v3/group/curve25519"
|
||||
|
||||
"github.com/certusone/wormhole/bridge/third_party/chainlink/secp256k1"
|
||||
)
|
||||
|
||||
var numSignatures = 5
|
||||
|
||||
var randomStream = cryptotest.NewStream(&testing.T{}, 0)
|
||||
|
||||
var printTests = false
|
||||
|
||||
func printTest(t *testing.T, msg *big.Int, private kyber.Scalar,
|
||||
public kyber.Point, signature Signature) {
|
||||
privateBytes, err := private.MarshalBinary()
|
||||
require.Nil(t, err)
|
||||
pX, pY := secp256k1.Coordinates(public)
|
||||
fmt.Printf(" ['%064x',\n '%064x',\n '%064x',\n '%064x',\n "+
|
||||
"'%064x',\n '%040x'],\n",
|
||||
msg, privateBytes, pX, pY, signature.Signature,
|
||||
signature.CommitmentPublicAddress)
|
||||
}
|
||||
|
||||
func TestShortSchnorr_SignAndVerify(t *testing.T) {
|
||||
if printTests {
|
||||
fmt.Printf("tests = [\n")
|
||||
}
|
||||
for i := 0; i < numSignatures; i++ {
|
||||
rand := mrand.New(mrand.NewSource(0))
|
||||
msg, err := crand.Int(rand, maxUint256)
|
||||
require.NoError(t, err)
|
||||
kp := secp256k1.Generate(randomStream)
|
||||
sig, err := Sign(kp.Private, msg)
|
||||
require.NoError(t, err, "failed to sign message")
|
||||
require.NoError(t, Verify(kp.Public, msg, sig),
|
||||
"failed to validate own signature")
|
||||
require.Error(t, Verify(kp.Public, u256Cardinality, sig),
|
||||
"failed to abort on too large a message")
|
||||
require.Error(t, Verify(kp.Public, big.NewInt(0).Neg(big.NewInt(1)), sig),
|
||||
"failed to abort on negative message")
|
||||
if printTests {
|
||||
printTest(t, msg, kp.Private, kp.Public, sig)
|
||||
}
|
||||
wrongMsg := big.NewInt(0).Add(msg, big.NewInt(1))
|
||||
require.Error(t, Verify(kp.Public, wrongMsg, sig),
|
||||
"failed to reject signature with bad message")
|
||||
wrongPublic := secp256k1Group.Point().Add(kp.Public, kp.Public)
|
||||
require.Error(t, Verify(wrongPublic, msg, sig),
|
||||
"failed to reject signature with bad public key")
|
||||
wrongSignature := &signature{
|
||||
CommitmentPublicAddress: sig.CommitmentPublicAddress,
|
||||
Signature: big.NewInt(0).Add(sig.Signature, one),
|
||||
}
|
||||
require.Error(t, Verify(kp.Public, msg, wrongSignature),
|
||||
"failed to reject bad signature")
|
||||
badPublicCommitmentAddress := &signature{Signature: sig.Signature}
|
||||
copy(badPublicCommitmentAddress.CommitmentPublicAddress[:],
|
||||
sig.CommitmentPublicAddress[:])
|
||||
badPublicCommitmentAddress.CommitmentPublicAddress[0] ^= 1 // Corrupt it
|
||||
require.Error(t, Verify(kp.Public, msg, badPublicCommitmentAddress),
|
||||
"failed to reject signature with bad public commitment")
|
||||
}
|
||||
if printTests {
|
||||
fmt.Println("]")
|
||||
}
|
||||
// Check other validations
|
||||
edSuite := curve25519.NewBlakeSHA256Curve25519(false)
|
||||
badScalar := edSuite.Scalar()
|
||||
_, err := Sign(badScalar, i())
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "not a secp256k1 scalar")
|
||||
err = Verify(edSuite.Point(), i(), NewSignature())
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "not a secp256k1 point")
|
||||
err = Verify(secp256k1Suite.Point(), i(), &signature{Signature: big.NewInt(-1)})
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "not a valid signature")
|
||||
err = Verify(secp256k1Suite.Point(), i(), &signature{Signature: u256Cardinality})
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "not a valid signature")
|
||||
}
|
||||
|
||||
func TestShortSchnorr_NewSignature(t *testing.T) {
|
||||
s := NewSignature()
|
||||
require.Equal(t, s.Signature, big.NewInt(0))
|
||||
}
|
||||
|
||||
func TestShortSchnorr_ChallengeHash(t *testing.T) {
|
||||
point := secp256k1Group.Point()
|
||||
var hash [20]byte
|
||||
h, err := ChallengeHash(point, hash, big.NewInt(-1))
|
||||
require.Nil(t, h)
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "msg must be a uint256")
|
||||
h, err = ChallengeHash(point, hash, u256Cardinality)
|
||||
require.Nil(t, h)
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "msg must be a uint256")
|
||||
}
|
||||
|
|
@ -0,0 +1,44 @@
|
|||
// Package secp256k1 is an implementation of the kyber.{Group,Point,Scalar}
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// XXX: Do not use in production until this code has been audited.
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// interfaces, based on btcd/btcec and kyber/group/mod
|
||||
//
|
||||
// XXX: NOT CONSTANT TIME!
|
||||
package secp256k1
|
||||
|
||||
import (
|
||||
"math/big"
|
||||
|
||||
secp256k1BTCD "github.com/btcsuite/btcd/btcec"
|
||||
|
||||
"go.dedis.ch/kyber/v3"
|
||||
)
|
||||
|
||||
// Secp256k1 represents the secp256k1 group.
|
||||
// There are no parameters and no initialization is required
|
||||
// because it supports only this one specific curve.
|
||||
type Secp256k1 struct{}
|
||||
|
||||
// s256 is the btcec representation of secp256k1.
|
||||
var s256 *secp256k1BTCD.KoblitzCurve = secp256k1BTCD.S256()
|
||||
|
||||
// String returns the name of the curve
|
||||
func (*Secp256k1) String() string { return "Secp256k1" }
|
||||
|
||||
var egScalar kyber.Scalar = newScalar(big.NewInt(0))
|
||||
var egPoint kyber.Point = &secp256k1Point{newFieldZero(), newFieldZero()}
|
||||
|
||||
// ScalarLen returns the length of a marshalled Scalar
|
||||
func (*Secp256k1) ScalarLen() int { return egScalar.MarshalSize() }
|
||||
|
||||
// Scalar creates a new Scalar for the prime-order group on the secp256k1 curve
|
||||
func (*Secp256k1) Scalar() kyber.Scalar { return newScalar(big.NewInt(0)) }
|
||||
|
||||
// PointLen returns the length of a marshalled Point
|
||||
func (*Secp256k1) PointLen() int { return egPoint.MarshalSize() }
|
||||
|
||||
// Point returns a new secp256k1 point
|
||||
func (*Secp256k1) Point() kyber.Point {
|
||||
return &secp256k1Point{newFieldZero(), newFieldZero()}
|
||||
}
|
||||
|
|
@ -0,0 +1,20 @@
|
|||
package secp256k1
|
||||
|
||||
import (
|
||||
"testing"
|
||||
|
||||
"github.com/stretchr/testify/require"
|
||||
)
|
||||
|
||||
var group = &Secp256k1{}
|
||||
|
||||
func TestSecp256k1_String(t *testing.T) {
|
||||
require.Equal(t, group.String(), "Secp256k1")
|
||||
}
|
||||
|
||||
func TestSecp256k1_Constructors(t *testing.T) {
|
||||
require.Equal(t, group.ScalarLen(), 32)
|
||||
require.Equal(t, ToInt(group.Scalar()), bigZero)
|
||||
require.Equal(t, group.PointLen(), 33)
|
||||
require.Equal(t, group.Point(), &secp256k1Point{fieldZero, fieldZero})
|
||||
}
|
||||
|
|
@ -0,0 +1,169 @@
|
|||
// Package secp256k1 is an implementation of the kyber.{Group,Point,Scalar}
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// XXX: Do not use in production until this code has been audited.
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// interfaces, based on btcd/btcec and kyber/group/mod
|
||||
//
|
||||
// XXX: NOT CONSTANT TIME!
|
||||
package secp256k1
|
||||
|
||||
// Arithmetic operations in the base field of secp256k1, i.e. ℤ/qℤ, where q is
|
||||
// the base field characteristic.
|
||||
|
||||
import (
|
||||
"crypto/cipher"
|
||||
"fmt"
|
||||
"math/big"
|
||||
|
||||
"go.dedis.ch/kyber/v3/util/random"
|
||||
)
|
||||
|
||||
// q is the field characteristic (cardinality) of the secp256k1 base field. All
|
||||
// arithmetic operations on the field are modulo this.
|
||||
var q = s256.P
|
||||
|
||||
type fieldElt big.Int
|
||||
|
||||
// newFieldZero returns a newly allocated field element.
|
||||
func newFieldZero() *fieldElt { return (*fieldElt)(big.NewInt(0)) }
|
||||
|
||||
// Int returns f as a big.Int
|
||||
func (f *fieldElt) int() *big.Int { return (*big.Int)(f) }
|
||||
|
||||
// modQ reduces f's underlying big.Int modulo q, and returns it
|
||||
func (f *fieldElt) modQ() *fieldElt {
|
||||
if f.int().Cmp(q) != -1 || f.int().Cmp(bigZero) == -1 {
|
||||
// f ∉ {0, ..., q-1}. Find the representative of f+qℤ in that set.
|
||||
//
|
||||
// Per Mod docstring, "Mod implements Euclidean modulus", meaning that after
|
||||
// this, f will be the smallest non-negative representative of its
|
||||
// equivalence class in ℤ/qℤ. TODO(alx): Make this faster
|
||||
f.int().Mod(f.int(), q)
|
||||
}
|
||||
return f
|
||||
}
|
||||
|
||||
// This differs from SetInt below, in that it does not take a copy of v.
|
||||
func fieldEltFromBigInt(v *big.Int) *fieldElt { return (*fieldElt)(v).modQ() }
|
||||
|
||||
func fieldEltFromInt(v int64) *fieldElt {
|
||||
return fieldEltFromBigInt(big.NewInt(int64(v))).modQ()
|
||||
}
|
||||
|
||||
var fieldZero = fieldEltFromInt(0)
|
||||
var bigZero = big.NewInt(0)
|
||||
|
||||
// String returns the string representation of f
|
||||
func (f *fieldElt) String() string {
|
||||
return fmt.Sprintf("fieldElt{%x}", f.int())
|
||||
}
|
||||
|
||||
// Equal returns true iff f=g, i.e. the backing big.Ints satisfy f ≡ g mod q
|
||||
func (f *fieldElt) Equal(g *fieldElt) bool {
|
||||
if f == (*fieldElt)(nil) && g == (*fieldElt)(nil) {
|
||||
return true
|
||||
}
|
||||
if f == (*fieldElt)(nil) { // f is nil, g is not
|
||||
return false
|
||||
}
|
||||
if g == (*fieldElt)(nil) { // g is nil, f is not
|
||||
return false
|
||||
}
|
||||
return bigZero.Cmp(newFieldZero().Sub(f, g).modQ().int()) == 0
|
||||
}
|
||||
|
||||
// Add sets f to the sum of a and b modulo q, and returns it.
|
||||
func (f *fieldElt) Add(a, b *fieldElt) *fieldElt {
|
||||
f.int().Add(a.int(), b.int())
|
||||
return f.modQ()
|
||||
}
|
||||
|
||||
// Sub sets f to a-b mod q, and returns it.
|
||||
func (f *fieldElt) Sub(a, b *fieldElt) *fieldElt {
|
||||
f.int().Sub(a.int(), b.int())
|
||||
return f.modQ()
|
||||
}
|
||||
|
||||
// Set sets f's value to v, and returns f.
|
||||
func (f *fieldElt) Set(v *fieldElt) *fieldElt {
|
||||
f.int().Set(v.int())
|
||||
return f.modQ()
|
||||
}
|
||||
|
||||
// SetInt sets f's value to v mod q, and returns f.
|
||||
func (f *fieldElt) SetInt(v *big.Int) *fieldElt {
|
||||
f.int().Set(v)
|
||||
return f.modQ()
|
||||
}
|
||||
|
||||
// Pick samples uniformly from {0, ..., q-1}, assigns sample to f, and returns f
|
||||
func (f *fieldElt) Pick(rand cipher.Stream) *fieldElt {
|
||||
return f.SetInt(random.Int(q, rand)) // random.Int safe because q≅2²⁵⁶, q<2²⁵⁶
|
||||
}
|
||||
|
||||
// Neg sets f to the negation of g modulo q, and returns it
|
||||
func (f *fieldElt) Neg(g *fieldElt) *fieldElt {
|
||||
f.int().Neg(g.int())
|
||||
return f.modQ()
|
||||
}
|
||||
|
||||
// Clone returns a new fieldElt, backed by a clone of f
|
||||
func (f *fieldElt) Clone() *fieldElt { return newFieldZero().Set(f.modQ()) }
|
||||
|
||||
// SetBytes sets f to the 32-byte big-endian value represented by buf, reduces
|
||||
// it, and returns it.
|
||||
func (f *fieldElt) SetBytes(buf [32]byte) *fieldElt {
|
||||
f.int().SetBytes(buf[:])
|
||||
return f.modQ()
|
||||
}
|
||||
|
||||
// Bytes returns the 32-byte big-endian representation of f
|
||||
func (f *fieldElt) Bytes() [32]byte {
|
||||
bytes := f.modQ().int().Bytes()
|
||||
if len(bytes) > 32 {
|
||||
panic("field element longer than 256 bits")
|
||||
}
|
||||
var rv [32]byte
|
||||
copy(rv[32-len(bytes):], bytes) // leftpad w zeros
|
||||
return rv
|
||||
}
|
||||
|
||||
var two = big.NewInt(2)
|
||||
|
||||
// square returns y² mod q
|
||||
func fieldSquare(y *fieldElt) *fieldElt {
|
||||
return fieldEltFromBigInt(newFieldZero().int().Exp(y.int(), two, q))
|
||||
}
|
||||
|
||||
// sqrtPower is s.t. n^sqrtPower≡sqrt(n) mod q, if n has a root at all. See
|
||||
// https://math.stackexchange.com/a/1816280, for instance
|
||||
//
|
||||
// What I'm calling sqrtPower is called q on the s256 struct. (See
|
||||
// btcec.initS256), which is confusing because the "Q" in "QPlus1Div4" refers to
|
||||
// the field characteristic
|
||||
var sqrtPower = s256.QPlus1Div4()
|
||||
|
||||
// maybeSqrtInField returns a square root of v, if it has any, else nil
|
||||
func maybeSqrtInField(v *fieldElt) *fieldElt {
|
||||
s := newFieldZero()
|
||||
s.int().Exp(v.int(), sqrtPower, q)
|
||||
if !fieldSquare(s).Equal(v) {
|
||||
return nil
|
||||
}
|
||||
return s
|
||||
}
|
||||
|
||||
var three = big.NewInt(3)
|
||||
var seven = fieldEltFromInt(7)
|
||||
|
||||
// rightHandSide returns the RHS of the secp256k1 equation, x³+7 mod q, given x
|
||||
func rightHandSide(x *fieldElt) *fieldElt {
|
||||
xCubed := newFieldZero()
|
||||
xCubed.int().Exp(x.int(), three, q)
|
||||
return xCubed.Add(xCubed, seven)
|
||||
}
|
||||
|
||||
// isEven returns true if f is even, false otherwise
|
||||
func (f *fieldElt) isEven() bool {
|
||||
return big.NewInt(0).Mod(f.int(), two).Cmp(big.NewInt(0)) == 0
|
||||
}
|
||||
|
|
@ -0,0 +1,159 @@
|
|||
package secp256k1
|
||||
|
||||
import (
|
||||
"encoding/hex"
|
||||
"math/big"
|
||||
"testing"
|
||||
|
||||
"github.com/stretchr/testify/assert"
|
||||
"github.com/stretchr/testify/require"
|
||||
|
||||
"github.com/smartcontractkit/chainlink/core/services/signatures/cryptotest"
|
||||
)
|
||||
|
||||
var numFieldSamples = 10
|
||||
|
||||
var observedFieldElts map[string]bool
|
||||
|
||||
func init() {
|
||||
observedFieldElts = make(map[string]bool)
|
||||
}
|
||||
|
||||
// observedFieldElt ensures that novel scalars are being picked.
|
||||
func observedFieldElt(t *testing.T, s *fieldElt) {
|
||||
elt := s.Bytes()
|
||||
data := hex.Dump(elt[:])
|
||||
require.False(t, observedFieldElts[data])
|
||||
observedFieldElts[data] = true
|
||||
}
|
||||
|
||||
var randomStream = cryptotest.NewStream(&testing.T{}, 0)
|
||||
|
||||
func TestField_SetIntAndEqual(t *testing.T) {
|
||||
tests := []int64{5, 67108864, 67108865, 4294967295}
|
||||
g := newFieldZero()
|
||||
for _, test := range tests {
|
||||
f := fieldEltFromInt(test)
|
||||
i := big.NewInt(test)
|
||||
g.SetInt(i)
|
||||
assert.Equal(t, f, g,
|
||||
"different values obtained for same input, using "+
|
||||
"SetInt vs fieldEltFromInt")
|
||||
i.Add(i, big.NewInt(1))
|
||||
assert.Equal(t, f, g,
|
||||
"SetInt should take a copy of the backing big.Int")
|
||||
}
|
||||
}
|
||||
|
||||
func TestField_String(t *testing.T) {
|
||||
require.Equal(t, fieldZero.String(), "fieldElt{0}")
|
||||
}
|
||||
|
||||
func TestField_Equal(t *testing.T) {
|
||||
require.True(t, (*fieldElt)(nil).Equal((*fieldElt)(nil)))
|
||||
require.False(t, (*fieldElt)(nil).Equal(fieldZero))
|
||||
require.False(t, fieldZero.Equal((*fieldElt)(nil)))
|
||||
}
|
||||
|
||||
func TestField_Set(t *testing.T) {
|
||||
f := fieldEltFromInt(1)
|
||||
g := newFieldZero()
|
||||
g.Set(f)
|
||||
g.Add(g, fieldEltFromInt(1))
|
||||
assert.Equal(t, f, fieldEltFromInt(1),
|
||||
"Set takes a copy of the backing big.Int")
|
||||
}
|
||||
|
||||
func TestFieldEltFromInt(t *testing.T) {
|
||||
assert.Equal(t, fieldEltFromInt(1), // Also tests fieldElt.modQ
|
||||
fieldEltFromBigInt(new(big.Int).Add(q, big.NewInt(1))),
|
||||
"only one representation of a ℤ/qℤ element should be used")
|
||||
}
|
||||
|
||||
func TestField_SmokeTestPick(t *testing.T) {
|
||||
f := newFieldZero()
|
||||
f.Pick(randomStream)
|
||||
observedFieldElt(t, f)
|
||||
assert.True(t, f.int().Cmp(big.NewInt(1000000000)) == 1,
|
||||
"should be greater than 1000000000, with very high probability")
|
||||
}
|
||||
|
||||
func TestField_Neg(t *testing.T) {
|
||||
f := newFieldZero()
|
||||
for i := 0; i < numFieldSamples; i++ {
|
||||
f.Pick(randomStream)
|
||||
observedFieldElt(t, f)
|
||||
g := f.Clone()
|
||||
g.Neg(g)
|
||||
require.True(t, g.Add(f, g).Equal(fieldZero),
|
||||
"adding something to its negative should give zero: "+
|
||||
"failed with %s", f)
|
||||
}
|
||||
}
|
||||
|
||||
func TestField_Sub(t *testing.T) {
|
||||
f := newFieldZero()
|
||||
for i := 0; i < numFieldSamples; i++ {
|
||||
f.Pick(randomStream)
|
||||
observedFieldElt(t, f)
|
||||
require.True(t, f.Sub(f, f).Equal(fieldZero),
|
||||
"subtracting something from itself should give zero: "+
|
||||
"failed with %s", f)
|
||||
}
|
||||
}
|
||||
|
||||
func TestField_Clone(t *testing.T) {
|
||||
f := fieldEltFromInt(1)
|
||||
g := f.Clone()
|
||||
h := f.Clone()
|
||||
assert.Equal(t, f, g, "clone output does not equal original")
|
||||
g.Add(f, f)
|
||||
assert.Equal(t, f, h, "clone does not make a copy")
|
||||
|
||||
}
|
||||
|
||||
func TestField_SetBytesAndBytes(t *testing.T) {
|
||||
f := newFieldZero()
|
||||
g := newFieldZero()
|
||||
for i := 0; i < numFieldSamples; i++ {
|
||||
f.Pick(randomStream)
|
||||
observedFieldElt(t, f)
|
||||
g.SetBytes(f.Bytes())
|
||||
require.True(t, g.Equal(f),
|
||||
"roundtrip through serialization should give same "+
|
||||
"result back: failed with %s", f)
|
||||
}
|
||||
}
|
||||
|
||||
func TestField_MaybeSquareRootInField(t *testing.T) {
|
||||
f := newFieldZero()
|
||||
minusOne := fieldEltFromInt(-1)
|
||||
assert.Nil(t, maybeSqrtInField(minusOne), "-1 is not a square, in this field")
|
||||
for i := 0; i < numFieldSamples; i++ {
|
||||
f.Pick(randomStream)
|
||||
observedFieldElt(t, f)
|
||||
require.True(t, f.int().Cmp(q) == -1, "picked larger value than q: %s", f)
|
||||
require.True(t, f.int().Cmp(big.NewInt(-1)) != -1,
|
||||
"backing int must be non-negative")
|
||||
s := fieldSquare(f)
|
||||
g := maybeSqrtInField(s)
|
||||
require.NotEqual(t, g, (*fieldElt)(nil))
|
||||
ng := newFieldZero().Neg(g)
|
||||
require.True(t, f.Equal(g) || f.Equal(ng), "squaring something and "+
|
||||
"taking the square root should give ± the original: failed with %s", f)
|
||||
bigIntSqrt := newFieldZero() // Cross-check against big.ModSqrt
|
||||
rv := bigIntSqrt.int().ModSqrt(s.int(), q)
|
||||
require.NotNil(t, rv)
|
||||
require.True(t, bigIntSqrt.Equal(g) || bigIntSqrt.Equal(ng))
|
||||
nonSquare := newFieldZero().Neg(s)
|
||||
rv = bigIntSqrt.int().ModSqrt(nonSquare.int(), q)
|
||||
require.Nil(t, rv, "ModSqrt indicates nonSquare is square")
|
||||
require.Nil(t, maybeSqrtInField(nonSquare), "the negative of square "+
|
||||
"should not be a square")
|
||||
}
|
||||
}
|
||||
|
||||
func TestField_RightHandSide(t *testing.T) {
|
||||
assert.Equal(t, rightHandSide(fieldEltFromInt(1)), fieldEltFromInt(8))
|
||||
assert.Equal(t, rightHandSide(fieldEltFromInt(2)), fieldEltFromInt(15))
|
||||
}
|
||||
|
|
@ -0,0 +1,379 @@
|
|||
// Package secp256k1 is an implementation of the kyber.{Group,Point,Scalar}
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// XXX: Do not use in production until this code has been audited.
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// interfaces, based on btcd/btcec and kyber/group/mod
|
||||
//
|
||||
// XXX: NOT CONSTANT TIME!
|
||||
package secp256k1
|
||||
|
||||
// Implementation of kyber.Point interface for elliptic-curve arithmetic
|
||||
// operations on secpk256k1.
|
||||
//
|
||||
// This is mostly a wrapper of the functionality provided by btcec
|
||||
|
||||
import (
|
||||
"crypto/cipher"
|
||||
"fmt"
|
||||
"io"
|
||||
"math/big"
|
||||
|
||||
"go.dedis.ch/kyber/v3"
|
||||
"go.dedis.ch/kyber/v3/util/key"
|
||||
"golang.org/x/crypto/sha3"
|
||||
)
|
||||
|
||||
// btcec's public interface uses this affine representation for points on the
|
||||
// curve. This does not naturally accommodate the point at infinity. btcec
|
||||
// represents it as (0, 0), which is not a point on {y²=x³+7}.
|
||||
type secp256k1Point struct {
|
||||
X *fieldElt
|
||||
Y *fieldElt
|
||||
}
|
||||
|
||||
func newPoint() *secp256k1Point {
|
||||
return &secp256k1Point{newFieldZero(), newFieldZero()}
|
||||
}
|
||||
|
||||
// String returns a string representation of P
|
||||
func (P *secp256k1Point) String() string {
|
||||
return fmt.Sprintf("Secp256k1{X: %s, Y: %s}", P.X, P.Y)
|
||||
}
|
||||
|
||||
// Equal returns true if p and pPrime represent the same point, false otherwise.
|
||||
func (P *secp256k1Point) Equal(pPrime kyber.Point) bool {
|
||||
return P.X.Equal(pPrime.(*secp256k1Point).X) &&
|
||||
P.Y.Equal(pPrime.(*secp256k1Point).Y)
|
||||
}
|
||||
|
||||
// Null sets p to the group-identity value, and returns it.
|
||||
func (P *secp256k1Point) Null() kyber.Point {
|
||||
P.X = fieldEltFromInt(0) // btcec representation of null point is (0,0)
|
||||
P.Y = fieldEltFromInt(0)
|
||||
return P
|
||||
}
|
||||
|
||||
// Base sets p to a copy of the standard group generator, and returns it.
|
||||
func (P *secp256k1Point) Base() kyber.Point {
|
||||
P.X.SetInt(s256.Gx)
|
||||
P.Y.SetInt(s256.Gy)
|
||||
return P
|
||||
}
|
||||
|
||||
// Pick sets P to a random point sampled from rand, and returns it.
|
||||
func (P *secp256k1Point) Pick(rand cipher.Stream) kyber.Point {
|
||||
for { // Keep trying X's until one fits the curve (~50% probability of
|
||||
// success each iteration
|
||||
P.X.Set(newFieldZero().Pick(rand))
|
||||
maybeRHS := rightHandSide(P.X)
|
||||
if maybeY := maybeSqrtInField(maybeRHS); maybeY != (*fieldElt)(nil) {
|
||||
P.Y.Set(maybeY)
|
||||
// Take the negative with 50% probability
|
||||
b := make([]byte, 1)
|
||||
rand.XORKeyStream(b[:], b[:])
|
||||
if b[0]&1 == 0 {
|
||||
P.Y.Neg(P.Y)
|
||||
}
|
||||
return P
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Set sets P to copies of pPrime's values, and returns it.
|
||||
func (P *secp256k1Point) Set(pPrime kyber.Point) kyber.Point {
|
||||
P.X.Set(pPrime.(*secp256k1Point).X)
|
||||
P.Y.Set(pPrime.(*secp256k1Point).Y)
|
||||
return P
|
||||
}
|
||||
|
||||
// Clone returns a copy of P.
|
||||
func (P *secp256k1Point) Clone() kyber.Point {
|
||||
return &secp256k1Point{X: P.X.Clone(), Y: P.Y.Clone()}
|
||||
}
|
||||
|
||||
// EmbedLen returns the number of bytes of data which can be embedded in a point.
|
||||
func (*secp256k1Point) EmbedLen() int {
|
||||
// Reserve the most-significant 8 bits for pseudo-randomness.
|
||||
// Reserve the least-significant 8 bits for embedded data length.
|
||||
return (255 - 8 - 8) / 8
|
||||
}
|
||||
|
||||
// Embed encodes a limited amount of specified data in the Point, using r as a
|
||||
// source of cryptographically secure random data. Implementations only embed
|
||||
// the first EmbedLen bytes of the given data.
|
||||
func (P *secp256k1Point) Embed(data []byte, r cipher.Stream) kyber.Point {
|
||||
numEmbedBytes := P.EmbedLen()
|
||||
if len(data) > numEmbedBytes {
|
||||
panic("too much data to embed in a point")
|
||||
}
|
||||
numEmbedBytes = len(data)
|
||||
var x [32]byte
|
||||
randStart := 1 // First byte to fill with random data
|
||||
if data != nil {
|
||||
x[0] = byte(numEmbedBytes) // Encode length in low 8 bits
|
||||
copy(x[1:1+numEmbedBytes], data) // Copy in data to embed
|
||||
randStart = 1 + numEmbedBytes
|
||||
}
|
||||
maxAttempts := 10000
|
||||
// Try random x ordinates satisfying the constraints, until one provides
|
||||
// a point on secp256k1
|
||||
for numAttempts := 0; numAttempts < maxAttempts; numAttempts++ {
|
||||
// Fill the rest of the x ordinate with random data
|
||||
r.XORKeyStream(x[randStart:], x[randStart:])
|
||||
xOrdinate := newFieldZero().SetBytes(x)
|
||||
// RHS of secp256k1 equation is x³+7 mod p. Success if square.
|
||||
// We optimistically don't use btcec.IsOnCurve, here, because we
|
||||
// hope to assign the intermediate result maybeY to P.Y
|
||||
secp256k1RHS := rightHandSide(xOrdinate)
|
||||
if maybeY := maybeSqrtInField(secp256k1RHS); maybeY != (*fieldElt)(nil) {
|
||||
P.X = xOrdinate // success: found (x,y) s.t. y²=x³+7
|
||||
P.Y = maybeY
|
||||
return P
|
||||
}
|
||||
}
|
||||
// Probability 2^{-maxAttempts}, under correct operation.
|
||||
panic("failed to find point satisfying all constraints")
|
||||
}
|
||||
|
||||
// Data returns data embedded in P, or an error if inconsistent with encoding
|
||||
func (P *secp256k1Point) Data() ([]byte, error) {
|
||||
b := P.X.Bytes()
|
||||
dataLength := int(b[0])
|
||||
if dataLength > P.EmbedLen() {
|
||||
return nil, fmt.Errorf("point specifies too much data")
|
||||
}
|
||||
return b[1 : dataLength+1], nil
|
||||
}
|
||||
|
||||
// Add sets P to a+b (secp256k1 group operation) and returns it.
|
||||
func (P *secp256k1Point) Add(a, b kyber.Point) kyber.Point {
|
||||
X, Y := s256.Add(
|
||||
a.(*secp256k1Point).X.int(), a.(*secp256k1Point).Y.int(),
|
||||
b.(*secp256k1Point).X.int(), b.(*secp256k1Point).Y.int())
|
||||
P.X.SetInt(X)
|
||||
P.Y.SetInt(Y)
|
||||
return P
|
||||
}
|
||||
|
||||
// Add sets P to a-b (secp256k1 group operation), and returns it.
|
||||
func (P *secp256k1Point) Sub(a, b kyber.Point) kyber.Point {
|
||||
X, Y := s256.Add(
|
||||
a.(*secp256k1Point).X.int(), a.(*secp256k1Point).Y.int(),
|
||||
b.(*secp256k1Point).X.int(),
|
||||
newFieldZero().Neg(b.(*secp256k1Point).Y).int()) // -b_y
|
||||
P.X.SetInt(X)
|
||||
P.Y.SetInt(Y)
|
||||
return P
|
||||
}
|
||||
|
||||
// Neg sets P to -a (in the secp256k1 group), and returns it.
|
||||
func (P *secp256k1Point) Neg(a kyber.Point) kyber.Point {
|
||||
P.X = a.(*secp256k1Point).X.Clone()
|
||||
P.Y = newFieldZero().Neg(a.(*secp256k1Point).Y)
|
||||
return P
|
||||
}
|
||||
|
||||
// Mul sets P to s*a (in the secp256k1 group, i.e. adding a to itself s times),
|
||||
// and returns it. If a is nil, it is replaced by the secp256k1 generator.
|
||||
func (P *secp256k1Point) Mul(s kyber.Scalar, a kyber.Point) kyber.Point {
|
||||
sBytes, err := s.(*secp256k1Scalar).MarshalBinary()
|
||||
if err != nil {
|
||||
panic(fmt.Errorf("failure while marshaling multiplier: %s",
|
||||
err))
|
||||
}
|
||||
var X, Y *big.Int
|
||||
if a == (*secp256k1Point)(nil) || a == nil {
|
||||
X, Y = s256.ScalarBaseMult(sBytes)
|
||||
} else {
|
||||
X, Y = s256.ScalarMult(a.(*secp256k1Point).X.int(),
|
||||
a.(*secp256k1Point).Y.int(), sBytes)
|
||||
}
|
||||
P.X.SetInt(X)
|
||||
P.Y.SetInt(Y)
|
||||
return P
|
||||
}
|
||||
|
||||
// MarshalBinary returns the concatenated big-endian representation of the X
|
||||
// ordinate and a byte which is 0 if Y is even, 1 if it's odd. Or it returns an
|
||||
// error on failure.
|
||||
func (P *secp256k1Point) MarshalBinary() ([]byte, error) {
|
||||
maybeSqrt := maybeSqrtInField(rightHandSide(P.X))
|
||||
if maybeSqrt == (*fieldElt)(nil) {
|
||||
return nil, fmt.Errorf("x³+7 not a square")
|
||||
}
|
||||
minusMaybeSqrt := newFieldZero().Neg(maybeSqrt)
|
||||
if !P.Y.Equal(maybeSqrt) && !P.Y.Equal(minusMaybeSqrt) {
|
||||
return nil, fmt.Errorf(
|
||||
"y ≠ ±maybeSqrt(x³+7), so not a point on the curve")
|
||||
}
|
||||
rv := make([]byte, P.MarshalSize())
|
||||
signByte := P.MarshalSize() - 1 // Last byte contains sign of Y.
|
||||
xordinate := P.X.Bytes()
|
||||
copyLen := copy(rv[:signByte], xordinate[:])
|
||||
if copyLen != P.MarshalSize()-1 {
|
||||
return []byte{}, fmt.Errorf("marshal of x ordinate too short")
|
||||
}
|
||||
if P.Y.isEven() {
|
||||
rv[signByte] = 0
|
||||
} else {
|
||||
rv[signByte] = 1
|
||||
}
|
||||
return rv, nil
|
||||
}
|
||||
|
||||
// MarshalSize returns the length of the byte representation of P
|
||||
func (P *secp256k1Point) MarshalSize() int { return 33 }
|
||||
|
||||
// MarshalID returns the ID for a secp256k1 point
|
||||
func (P *secp256k1Point) MarshalID() [8]byte {
|
||||
return [8]byte{'s', 'p', '2', '5', '6', '.', 'p', 'o'}
|
||||
}
|
||||
|
||||
// UnmarshalBinary sets P to the point represented by contents of buf, or
|
||||
// returns an non-nil error
|
||||
func (P *secp256k1Point) UnmarshalBinary(buf []byte) error {
|
||||
var err error
|
||||
if len(buf) != P.MarshalSize() {
|
||||
err = fmt.Errorf("wrong length for marshaled point")
|
||||
}
|
||||
if err == nil && !(buf[32] == 0 || buf[32] == 1) {
|
||||
err = fmt.Errorf("bad sign byte (the last one)")
|
||||
}
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
var xordinate [32]byte
|
||||
copy(xordinate[:], buf[:32])
|
||||
P.X = newFieldZero().SetBytes(xordinate)
|
||||
secp256k1RHS := rightHandSide(P.X)
|
||||
maybeY := maybeSqrtInField(secp256k1RHS)
|
||||
if maybeY == (*fieldElt)(nil) {
|
||||
return fmt.Errorf("x ordinate does not correspond to a curve point")
|
||||
}
|
||||
isEven := maybeY.isEven()
|
||||
P.Y.Set(maybeY)
|
||||
if (buf[32] == 0 && !isEven) || (buf[32] == 1 && isEven) {
|
||||
P.Y.Neg(P.Y)
|
||||
} else {
|
||||
if buf[32] != 0 && buf[32] != 1 {
|
||||
return fmt.Errorf("parity byte must be 0 or 1")
|
||||
}
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
// MarshalTo writes the serialized P to w, and returns the number of bytes
|
||||
// written, or an error on failure.
|
||||
func (P *secp256k1Point) MarshalTo(w io.Writer) (int, error) {
|
||||
buf, err := P.MarshalBinary()
|
||||
if err != nil {
|
||||
return 0, err
|
||||
}
|
||||
return w.Write(buf)
|
||||
}
|
||||
|
||||
// UnmarshalFrom sets P to the secp256k1 point represented by bytes read from r,
|
||||
// and returns the number of bytes read, or an error on failure.
|
||||
func (P *secp256k1Point) UnmarshalFrom(r io.Reader) (int, error) {
|
||||
buf := make([]byte, P.MarshalSize())
|
||||
n, err := io.ReadFull(r, buf)
|
||||
if err != nil {
|
||||
return 0, err
|
||||
}
|
||||
return n, P.UnmarshalBinary(buf)
|
||||
}
|
||||
|
||||
// EthereumAddress returns the 160-bit address corresponding to p as public key.
|
||||
func EthereumAddress(p kyber.Point) (rv [20]byte) {
|
||||
// The Ethereum address of P is the bottom 160 bits of keccak256(P.X‖P.Y),
|
||||
// where P.X and P.Y are represented in 32 bytes as big-endian. See equations
|
||||
// (277, 284) of Ethereum Yellow Paper version 3e36772, or go-ethereum's
|
||||
// crypto.PubkeyToAddress.
|
||||
h := sha3.NewLegacyKeccak256()
|
||||
if _, err := h.Write(LongMarshal(p)); err != nil {
|
||||
panic(err)
|
||||
}
|
||||
copy(rv[:], h.Sum(nil)[12:])
|
||||
return rv
|
||||
}
|
||||
|
||||
// IsSecp256k1Point returns true if p is a secp256k1Point
|
||||
func IsSecp256k1Point(p kyber.Point) bool {
|
||||
switch p.(type) {
|
||||
case *secp256k1Point:
|
||||
return true
|
||||
default:
|
||||
return false
|
||||
}
|
||||
}
|
||||
|
||||
// Coordinates returns the coordinates of p
|
||||
func Coordinates(p kyber.Point) (*big.Int, *big.Int) {
|
||||
return p.(*secp256k1Point).X.int(), p.(*secp256k1Point).Y.int()
|
||||
}
|
||||
|
||||
// ValidPublicKey returns true iff p can be used in the optimized on-chain
|
||||
// Schnorr-signature verification. See SchnorrSECP256K1.sol for details.
|
||||
func ValidPublicKey(p kyber.Point) bool {
|
||||
if p == (*secp256k1Point)(nil) || p == nil {
|
||||
return false
|
||||
}
|
||||
P, ok := p.(*secp256k1Point)
|
||||
if !ok {
|
||||
return false
|
||||
}
|
||||
maybeY := maybeSqrtInField(rightHandSide(P.X))
|
||||
return maybeY != nil && (P.Y.Equal(maybeY) || P.Y.Equal(maybeY.Neg(maybeY)))
|
||||
}
|
||||
|
||||
// Generate generates a public/private key pair, which can be verified cheaply
|
||||
// on-chain
|
||||
func Generate(random cipher.Stream) *key.Pair {
|
||||
p := key.Pair{}
|
||||
for !ValidPublicKey(p.Public) {
|
||||
p.Private = (&Secp256k1{}).Scalar().Pick(random)
|
||||
p.Public = (&Secp256k1{}).Point().Mul(p.Private, nil)
|
||||
}
|
||||
return &p
|
||||
}
|
||||
|
||||
// LongMarshal returns the concatenated coordinates serialized as uint256's
|
||||
func LongMarshal(p kyber.Point) []byte {
|
||||
xMarshal := p.(*secp256k1Point).X.Bytes()
|
||||
yMarshal := p.(*secp256k1Point).Y.Bytes()
|
||||
return append(xMarshal[:], yMarshal[:]...)
|
||||
}
|
||||
|
||||
// LongUnmarshal returns the secp256k1 point represented by m, as a concatenated
|
||||
// pair of uint256's
|
||||
func LongUnmarshal(m []byte) (kyber.Point, error) {
|
||||
if len(m) != 64 {
|
||||
return nil, fmt.Errorf(
|
||||
"0x%x does not represent an uncompressed secp256k1Point. Should be length 64, but is length %d",
|
||||
m, len(m))
|
||||
}
|
||||
p := newPoint()
|
||||
p.X.SetInt(big.NewInt(0).SetBytes(m[:32]))
|
||||
p.Y.SetInt(big.NewInt(0).SetBytes(m[32:]))
|
||||
if !ValidPublicKey(p) {
|
||||
return nil, fmt.Errorf("%s is not a valid secp256k1 point", p)
|
||||
}
|
||||
return p, nil
|
||||
}
|
||||
|
||||
// ScalarToPublicPoint returns the public secp256k1 point associated to s
|
||||
func ScalarToPublicPoint(s kyber.Scalar) kyber.Point {
|
||||
publicPoint := (&Secp256k1{}).Point()
|
||||
return publicPoint.Mul(s, nil)
|
||||
}
|
||||
|
||||
// SetCoordinates returns the point (x,y), or panics if an invalid secp256k1Point
|
||||
func SetCoordinates(x, y *big.Int) kyber.Point {
|
||||
rv := newPoint()
|
||||
rv.X.SetInt(x)
|
||||
rv.Y.SetInt(y)
|
||||
if !ValidPublicKey(rv) {
|
||||
panic("point requested from invalid coordinates")
|
||||
}
|
||||
return rv
|
||||
}
|
||||
|
|
@ -0,0 +1,232 @@
|
|||
package secp256k1
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"crypto/rand"
|
||||
"fmt"
|
||||
"math/big"
|
||||
"testing"
|
||||
|
||||
"go.dedis.ch/kyber/v3/group/curve25519"
|
||||
|
||||
"github.com/stretchr/testify/assert"
|
||||
"github.com/stretchr/testify/require"
|
||||
|
||||
"github.com/smartcontractkit/chainlink/core/services/signatures/cryptotest"
|
||||
)
|
||||
|
||||
var numPointSamples = 10
|
||||
|
||||
var randomStreamPoint = cryptotest.NewStream(&testing.T{}, 0)
|
||||
|
||||
func TestPoint_String(t *testing.T) {
|
||||
require.Equal(t, newPoint().String(),
|
||||
"Secp256k1{X: fieldElt{0}, Y: fieldElt{0}}")
|
||||
}
|
||||
|
||||
func TestPoint_CloneAndEqual(t *testing.T) {
|
||||
f := newPoint()
|
||||
for i := 0; i < numPointSamples; i++ {
|
||||
g := f.Clone()
|
||||
f.Pick(randomStreamPoint)
|
||||
assert.NotEqual(t, f, g,
|
||||
"modifying original shouldn't change clone")
|
||||
g, h := f.Clone(), f.Clone()
|
||||
assert.Equal(t, f, g, "clones should be equal")
|
||||
g.Add(g, f)
|
||||
assert.Equal(t, h, f,
|
||||
"modifying a clone shouldn't change originial")
|
||||
}
|
||||
}
|
||||
|
||||
func TestPoint_NullAndAdd(t *testing.T) {
|
||||
f, g := newPoint(), newPoint()
|
||||
for i := 0; i < numPointSamples; i++ {
|
||||
g.Null()
|
||||
f.Pick(randomStreamPoint)
|
||||
g.Add(f, g)
|
||||
assert.Equal(t, f, g, "adding zero should have no effect")
|
||||
}
|
||||
}
|
||||
|
||||
func TestPoint_Set(t *testing.T) {
|
||||
p := newPoint()
|
||||
base := newPoint().Base()
|
||||
assert.NotEqual(t, p, base, "generator should not be zero")
|
||||
p.Set(base)
|
||||
assert.Equal(t, p, base, "setting to generator should yield generator")
|
||||
}
|
||||
|
||||
func TestPoint_Embed(t *testing.T) {
|
||||
p := newPoint()
|
||||
for i := 0; i < numPointSamples; i++ {
|
||||
data := make([]byte, p.EmbedLen())
|
||||
_, err := rand.Read(data)
|
||||
require.Nil(t, err)
|
||||
p.Embed(data, randomStreamPoint)
|
||||
require.True(t, s256.IsOnCurve(p.X.int(), p.Y.int()),
|
||||
"should embed to a secp256k1 point")
|
||||
output, err := p.Data()
|
||||
require.NoError(t, err)
|
||||
require.True(t, bytes.Equal(data, output),
|
||||
"should get same value back after round-trip "+
|
||||
"embedding, got %v, then %v", data, output)
|
||||
}
|
||||
var uint256Bytes [32]byte
|
||||
uint256Bytes[0] = 30
|
||||
p.X.SetBytes(uint256Bytes)
|
||||
_, err := p.Data()
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "specifies too much data")
|
||||
var b bytes.Buffer
|
||||
p.Pick(randomStreamPoint)
|
||||
_, err = p.MarshalTo(&b)
|
||||
require.NoError(t, err)
|
||||
_, err = p.UnmarshalFrom(&b)
|
||||
require.NoError(t, err)
|
||||
data := make([]byte, p.EmbedLen()+1) // Check length validation. This test
|
||||
defer func() { // comes last, because it triggers panic
|
||||
r := recover()
|
||||
require.NotNil(t, r, "calling embed with too much data should panic")
|
||||
require.Contains(t, r, "too much data to embed in a point")
|
||||
}()
|
||||
p.Embed(data, randomStreamPoint)
|
||||
}
|
||||
|
||||
func TestPoint_AddSubAndNeg(t *testing.T) {
|
||||
zero := newPoint().Null()
|
||||
p := newPoint()
|
||||
for i := 0; i < numPointSamples; i++ {
|
||||
p.Pick(randomStreamPoint)
|
||||
q := p.Clone()
|
||||
p.Sub(p, q)
|
||||
require.True(t, p.Equal(zero),
|
||||
"subtracting a point from itself should give zero, "+
|
||||
"got %v - %v = %v ≠ %v", q, q, p, zero)
|
||||
p.Neg(q)
|
||||
r := newPoint().Add(p, q)
|
||||
require.True(t, r.Equal(zero),
|
||||
"adding a point to its negative should give zero"+
|
||||
" got %v+%v=%v≠%v", q, p, r, zero)
|
||||
r.Neg(q)
|
||||
p.Sub(q, r)
|
||||
s := newPoint().Add(q, q)
|
||||
require.True(t, p.Equal(s), "q-(-q)=q+q?"+
|
||||
" got %v-%v=%v≠%v", q, r, p, s)
|
||||
}
|
||||
}
|
||||
|
||||
func TestPoint_Mul(t *testing.T) {
|
||||
zero := newPoint().Null()
|
||||
multiplier := newScalar(bigZero)
|
||||
one := newScalar(big.NewInt(int64(1)))
|
||||
var p *secp256k1Point
|
||||
for i := 0; i < numPointSamples/5; i++ {
|
||||
if i%20 == 0 {
|
||||
p = nil // Test default to generator point
|
||||
} else {
|
||||
p = newPoint()
|
||||
p.Pick(randomStreamPoint)
|
||||
}
|
||||
multiplier.Pick(randomStreamPoint)
|
||||
q := newPoint().Mul(one, p)
|
||||
comparee := newPoint()
|
||||
if p == (*secp256k1Point)(nil) {
|
||||
comparee.Base()
|
||||
} else {
|
||||
comparee = p.Clone().(*secp256k1Point)
|
||||
}
|
||||
require.True(t, comparee.Equal(q), "1*p=p? %v * %v ≠ %v", one,
|
||||
comparee, q)
|
||||
q.Mul(multiplier, p)
|
||||
negMultiplier := newScalar(bigZero).Neg(multiplier)
|
||||
r := newPoint().Mul(negMultiplier, p)
|
||||
s := newPoint().Add(q, r)
|
||||
require.True(t, s.Equal(zero), "s*p+(-s)*p=0? got "+
|
||||
"%v*%v + %v*%v = %v + %v = %v ≠ %v", multiplier, p,
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
func TestPoint_Marshal(t *testing.T) {
|
||||
p := newPoint()
|
||||
for i := 0; i < numPointSamples; i++ {
|
||||
p.Pick(randomStreamPoint)
|
||||
serialized, err := p.MarshalBinary()
|
||||
require.Nil(t, err)
|
||||
q := newPoint()
|
||||
err = q.UnmarshalBinary(serialized)
|
||||
require.Nil(t, err)
|
||||
require.True(t, p.Equal(q), "%v marshalled to %x, which "+
|
||||
"unmarshalled to %v", p, serialized, q)
|
||||
}
|
||||
p.X.SetInt(big.NewInt(0)) // 0³+7 is not a square in the base field.
|
||||
_, err := p.MarshalBinary()
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "not a square")
|
||||
p.X.SetInt(big.NewInt(1))
|
||||
_, err = p.MarshalBinary()
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "not a point on the curve")
|
||||
id := p.MarshalID()
|
||||
require.Equal(t, string(id[:]), "sp256.po")
|
||||
data := make([]byte, 34)
|
||||
err = p.UnmarshalBinary(data)
|
||||
require.Error(t, err)
|
||||
require.Contains(t, err.Error(), "wrong length for marshaled point")
|
||||
require.Contains(t, p.UnmarshalBinary(data[:32]).Error(),
|
||||
"wrong length for marshaled point")
|
||||
data[32] = 2
|
||||
require.Contains(t, p.UnmarshalBinary(data[:33]).Error(),
|
||||
"bad sign byte")
|
||||
data[32] = 0
|
||||
data[31] = 5 // I.e., x-ordinate is now 5
|
||||
require.Contains(t, p.UnmarshalBinary(data[:33]).Error(),
|
||||
"does not correspond to a curve point")
|
||||
}
|
||||
|
||||
func TestPoint_BaseTakesCopy(t *testing.T) {
|
||||
p := newPoint().Base()
|
||||
p.Add(p, p)
|
||||
q := newPoint().Base()
|
||||
assert.False(t, p.Equal(q),
|
||||
"modifying output from Base changes S256.G{x,y}")
|
||||
}
|
||||
|
||||
func TestPoint_EthereumAddress(t *testing.T) {
|
||||
// Example taken from
|
||||
// https://theethereum.wiki/w/index.php/Accounts,_Addresses,_Public_And_Private_Keys,_And_Tokens
|
||||
pString := "3a1076bf45ab87712ad64ccb3b10217737f7faacbf2872e88fdd9a537d8fe266"
|
||||
pInt, ok := big.NewInt(0).SetString(pString, 16)
|
||||
require.True(t, ok, "failed to parse private key")
|
||||
private := newScalar(pInt)
|
||||
public := newPoint().Mul(private, nil)
|
||||
address := EthereumAddress(public)
|
||||
assert.Equal(t, fmt.Sprintf("%x", address),
|
||||
"c2d7cf95645d33006175b78989035c7c9061d3f9")
|
||||
}
|
||||
|
||||
func TestIsSecp256k1Point(t *testing.T) {
|
||||
p := curve25519.NewBlakeSHA256Curve25519(false).Point()
|
||||
require.False(t, IsSecp256k1Point(p))
|
||||
require.True(t, IsSecp256k1Point(newPoint()))
|
||||
}
|
||||
|
||||
func TestCoordinates(t *testing.T) {
|
||||
x, y := Coordinates(newPoint())
|
||||
require.Equal(t, x, bigZero)
|
||||
require.Equal(t, y, bigZero)
|
||||
}
|
||||
|
||||
func TestValidPublicKey(t *testing.T) {
|
||||
require.False(t, ValidPublicKey(newPoint()), "zero is not a valid key")
|
||||
require.True(t, ValidPublicKey(newPoint().Base()))
|
||||
}
|
||||
|
||||
func TestGenerate(t *testing.T) {
|
||||
for {
|
||||
if ValidPublicKey(Generate(randomStreamPoint).Public) {
|
||||
break
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
@ -0,0 +1,228 @@
|
|||
// Package secp256k1 is an implementation of the kyber.{Group,Point,Scalcar}
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// XXX: Do not use in production until this code has been audited.
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// interfaces, based on btcd/btcec and kyber/group/mod
|
||||
//
|
||||
// XXX: NOT CONSTANT TIME!
|
||||
package secp256k1
|
||||
|
||||
// Implementation of kyber.Scalar interface for arithmetic operations mod the
|
||||
// order of the secpk256k1 group (i.e. hex value
|
||||
// 0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141.)
|
||||
|
||||
import (
|
||||
"crypto/cipher"
|
||||
"fmt"
|
||||
"io"
|
||||
"math/big"
|
||||
|
||||
secp256k1BTCD "github.com/btcsuite/btcd/btcec"
|
||||
"github.com/ethereum/go-ethereum/common"
|
||||
|
||||
"go.dedis.ch/kyber/v3"
|
||||
"go.dedis.ch/kyber/v3/util/random"
|
||||
)
|
||||
|
||||
var GroupOrder = secp256k1BTCD.S256().N
|
||||
|
||||
type secp256k1Scalar big.Int
|
||||
|
||||
// AllowVarTime, if passed true indicates that variable-time operations may be
|
||||
// used on s.
|
||||
func (s *secp256k1Scalar) AllowVarTime(varTimeAllowed bool) {
|
||||
// Since constant-time operations are unimplemented for secp256k1, a
|
||||
// value of false panics.
|
||||
if !varTimeAllowed {
|
||||
panic("implementation is not constant-time!")
|
||||
}
|
||||
}
|
||||
|
||||
// newScalar returns a secpk256k1 scalar, with value v modulo GroupOrder.
|
||||
func newScalar(v *big.Int) kyber.Scalar {
|
||||
return (*secp256k1Scalar)(zero().Mod(v, GroupOrder))
|
||||
}
|
||||
|
||||
func zero() *big.Int { return big.NewInt(0) }
|
||||
|
||||
func ToInt(s kyber.Scalar) *big.Int { return (*big.Int)(s.(*secp256k1Scalar)) }
|
||||
|
||||
func (s *secp256k1Scalar) int() *big.Int { return (*big.Int)(s) }
|
||||
|
||||
func (s *secp256k1Scalar) modG() kyber.Scalar {
|
||||
// TODO(alx): Make this faster
|
||||
s.int().Mod(s.int(), GroupOrder)
|
||||
return s
|
||||
}
|
||||
|
||||
func (s *secp256k1Scalar) String() string {
|
||||
return fmt.Sprintf("scalar{%x}", (*big.Int)(s))
|
||||
}
|
||||
|
||||
var scalarZero = zero()
|
||||
|
||||
// Equal returns true if s and sPrime represent the same value modulo the group
|
||||
// order, false otherwise
|
||||
func (s *secp256k1Scalar) Equal(sPrime kyber.Scalar) bool {
|
||||
difference := zero().Sub(s.int(), ToInt(sPrime))
|
||||
return scalarZero.Cmp(difference.Mod(difference, GroupOrder)) == 0
|
||||
}
|
||||
|
||||
// Set copies sPrime's value (modulo GroupOrder) to s, and returns it
|
||||
func (s *secp256k1Scalar) Set(sPrime kyber.Scalar) kyber.Scalar {
|
||||
return (*secp256k1Scalar)(s.int().Mod(ToInt(sPrime), GroupOrder))
|
||||
}
|
||||
|
||||
// Clone returns a copy of s mod GroupOrder
|
||||
func (s *secp256k1Scalar) Clone() kyber.Scalar {
|
||||
return (*secp256k1Scalar)(zero().Mod(s.int(), GroupOrder))
|
||||
}
|
||||
|
||||
// SetInt64 returns s with value set to v modulo GroupOrder
|
||||
func (s *secp256k1Scalar) SetInt64(v int64) kyber.Scalar {
|
||||
return (*secp256k1Scalar)(s.int().SetInt64(v)).modG()
|
||||
}
|
||||
|
||||
// Zero sets s to 0 mod GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) Zero() kyber.Scalar {
|
||||
return s.SetInt64(0)
|
||||
}
|
||||
|
||||
// Add sets s to a+b mod GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) Add(a, b kyber.Scalar) kyber.Scalar {
|
||||
s.int().Add(ToInt(a), ToInt(b))
|
||||
return s.modG()
|
||||
}
|
||||
|
||||
// Sub sets s to a-b mod GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) Sub(a, b kyber.Scalar) kyber.Scalar {
|
||||
s.int().Sub(ToInt(a), ToInt(b))
|
||||
return s.modG()
|
||||
}
|
||||
|
||||
// Neg sets s to -a mod GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) Neg(a kyber.Scalar) kyber.Scalar {
|
||||
s.int().Neg(ToInt(a))
|
||||
return s.modG()
|
||||
}
|
||||
|
||||
// One sets s to 1 mod GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) One() kyber.Scalar {
|
||||
return s.SetInt64(1)
|
||||
}
|
||||
|
||||
// Mul sets s to a*b mod GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) Mul(a, b kyber.Scalar) kyber.Scalar {
|
||||
// TODO(alx): Make this faster
|
||||
s.int().Mul(ToInt(a), ToInt(b))
|
||||
return s.modG()
|
||||
}
|
||||
|
||||
// Div sets s to a*b⁻¹ mod GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) Div(a, b kyber.Scalar) kyber.Scalar {
|
||||
if ToInt(b).Cmp(scalarZero) == 0 {
|
||||
panic("attempt to divide by zero")
|
||||
}
|
||||
// TODO(alx): Make this faster
|
||||
s.int().Mul(ToInt(a), zero().ModInverse(ToInt(b), GroupOrder))
|
||||
return s.modG()
|
||||
}
|
||||
|
||||
// Inv sets s to s⁻¹ mod GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) Inv(a kyber.Scalar) kyber.Scalar {
|
||||
if ToInt(a).Cmp(scalarZero) == 0 {
|
||||
panic("attempt to divide by zero")
|
||||
}
|
||||
s.int().ModInverse(ToInt(a), GroupOrder)
|
||||
return s
|
||||
}
|
||||
|
||||
// Pick sets s to a random value mod GroupOrder sampled from rand, and returns
|
||||
// it
|
||||
func (s *secp256k1Scalar) Pick(rand cipher.Stream) kyber.Scalar {
|
||||
return s.Set((*secp256k1Scalar)(random.Int(GroupOrder, rand)))
|
||||
}
|
||||
|
||||
// MarshalBinary returns the big-endian byte representation of s, or an error on
|
||||
// failure
|
||||
func (s *secp256k1Scalar) MarshalBinary() ([]byte, error) {
|
||||
b := ToInt(s.modG()).Bytes()
|
||||
// leftpad with zeros
|
||||
rv := append(make([]byte, s.MarshalSize()-len(b)), b...)
|
||||
if len(rv) != s.MarshalSize() {
|
||||
return nil, fmt.Errorf("marshalled scalar to wrong length")
|
||||
}
|
||||
return rv, nil
|
||||
}
|
||||
|
||||
// MarshalSize returns the length of the byte representation of s
|
||||
func (s *secp256k1Scalar) MarshalSize() int { return 32 }
|
||||
|
||||
// MarshalID returns the ID for a secp256k1 scalar
|
||||
func (s *secp256k1Scalar) MarshalID() [8]byte {
|
||||
return [8]byte{'s', 'p', '2', '5', '6', '.', 's', 'c'}
|
||||
}
|
||||
|
||||
// UnmarshalBinary sets s to the scalar represented by the contents of buf,
|
||||
// returning error on failure.
|
||||
func (s *secp256k1Scalar) UnmarshalBinary(buf []byte) error {
|
||||
if len(buf) != s.MarshalSize() {
|
||||
return fmt.Errorf("cannot unmarshal to scalar: wrong length")
|
||||
}
|
||||
s.int().Mod(s.int().SetBytes(buf), GroupOrder)
|
||||
return nil
|
||||
}
|
||||
|
||||
// MarshalTo writes the serialized s to w, and returns the number of bytes
|
||||
// written, or an error on failure.
|
||||
func (s *secp256k1Scalar) MarshalTo(w io.Writer) (int, error) {
|
||||
buf, err := s.MarshalBinary()
|
||||
if err != nil {
|
||||
return 0, fmt.Errorf("cannot marshal binary: %s", err)
|
||||
}
|
||||
return w.Write(buf)
|
||||
}
|
||||
|
||||
// UnmarshalFrom sets s to the scalar represented by bytes read from r, and
|
||||
// returns the number of bytes read, or an error on failure.
|
||||
func (s *secp256k1Scalar) UnmarshalFrom(r io.Reader) (int, error) {
|
||||
buf := make([]byte, s.MarshalSize())
|
||||
n, err := io.ReadFull(r, buf)
|
||||
if err != nil {
|
||||
return n, err
|
||||
}
|
||||
return n, s.UnmarshalBinary(buf)
|
||||
}
|
||||
|
||||
// SetBytes sets s to the number with big-endian representation a mod
|
||||
// GroupOrder, and returns it
|
||||
func (s *secp256k1Scalar) SetBytes(a []byte) kyber.Scalar {
|
||||
return ((*secp256k1Scalar)(s.int().SetBytes(a))).modG()
|
||||
}
|
||||
|
||||
// IsSecp256k1Scalar returns true if p is a secp256k1Scalar
|
||||
func IsSecp256k1Scalar(s kyber.Scalar) bool {
|
||||
switch s := s.(type) {
|
||||
case *secp256k1Scalar:
|
||||
s.modG()
|
||||
return true
|
||||
default:
|
||||
return false
|
||||
}
|
||||
}
|
||||
|
||||
// IntToScalar returns i wrapped as a big.Int.
|
||||
//
|
||||
// May modify i to reduce mod GroupOrder
|
||||
func IntToScalar(i *big.Int) kyber.Scalar {
|
||||
return ((*secp256k1Scalar)(i)).modG()
|
||||
}
|
||||
|
||||
func ScalarToHash(s kyber.Scalar) common.Hash {
|
||||
return common.BigToHash(ToInt(s.(*secp256k1Scalar)))
|
||||
}
|
||||
|
||||
// RepresentsScalar returns true iff i is in the right range to be a scalar
|
||||
func RepresentsScalar(i *big.Int) bool {
|
||||
return i.Cmp(GroupOrder) == -1
|
||||
}
|
||||
|
|
@ -0,0 +1,189 @@
|
|||
package secp256k1
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"encoding/hex"
|
||||
"math/big"
|
||||
"testing"
|
||||
|
||||
"github.com/stretchr/testify/assert"
|
||||
"github.com/stretchr/testify/require"
|
||||
|
||||
"go.dedis.ch/kyber/v3"
|
||||
"go.dedis.ch/kyber/v3/group/curve25519"
|
||||
|
||||
"github.com/smartcontractkit/chainlink/core/services/signatures/cryptotest"
|
||||
)
|
||||
|
||||
var numScalarSamples = 10
|
||||
|
||||
var observedScalars map[string]bool
|
||||
|
||||
func init() {
|
||||
observedScalars = make(map[string]bool)
|
||||
}
|
||||
|
||||
// observedScalar ensures that novel scalars are being picked.
|
||||
func observedScalar(t *testing.T, s kyber.Scalar) {
|
||||
data, err := s.(*secp256k1Scalar).modG().MarshalBinary()
|
||||
require.NoError(t, err)
|
||||
scalar := hex.Dump(data)
|
||||
require.False(t, observedScalars[scalar])
|
||||
observedScalars[scalar] = true
|
||||
}
|
||||
|
||||
var randomStreamScalar = cryptotest.NewStream(&testing.T{}, 0)
|
||||
|
||||
func TestScalar_SetAndEqual(t *testing.T) {
|
||||
tests := []int64{5, 67108864, 67108865, 4294967295}
|
||||
g := newScalar(scalarZero)
|
||||
for _, test := range tests {
|
||||
f := newScalar(big.NewInt(test))
|
||||
g.Set(f)
|
||||
assert.Equal(t, f, g,
|
||||
"the method Set should give the same value to receiver")
|
||||
f.Add(f, newScalar(big.NewInt(1)))
|
||||
assert.NotEqual(t, f, g,
|
||||
"SetInt should take a copy of the backing big.Int")
|
||||
}
|
||||
}
|
||||
|
||||
func TestNewScalar(t *testing.T) {
|
||||
one := newScalar(big.NewInt(1))
|
||||
assert.Equal(t, ToInt(one),
|
||||
ToInt(newScalar(big.NewInt(0).Add(ToInt(one), GroupOrder))),
|
||||
"equivalence classes mod GroupOrder not equal")
|
||||
}
|
||||
|
||||
func TestScalar_SmokeTestPick(t *testing.T) {
|
||||
f := newScalar(scalarZero).Clone()
|
||||
for i := 0; i < numScalarSamples; i++ {
|
||||
f.Pick(randomStreamScalar)
|
||||
observedScalar(t, f)
|
||||
require.True(t, ToInt(f).Cmp(big.NewInt(1000000000)) == 1,
|
||||
"implausibly low value returned from Pick: %v", f)
|
||||
}
|
||||
}
|
||||
|
||||
func TestScalar_Neg(t *testing.T) {
|
||||
f := newScalar(scalarZero).Clone()
|
||||
for i := 0; i < numScalarSamples; i++ {
|
||||
f.Pick(randomStreamScalar)
|
||||
observedScalar(t, f)
|
||||
g := f.Clone()
|
||||
g.Neg(g)
|
||||
require.True(t, g.Add(f, g).Equal(newScalar(scalarZero)))
|
||||
}
|
||||
}
|
||||
|
||||
func TestScalar_Sub(t *testing.T) {
|
||||
f := newScalar(scalarZero).Clone()
|
||||
for i := 0; i < numScalarSamples; i++ {
|
||||
f.Pick(randomStreamScalar)
|
||||
observedScalar(t, f)
|
||||
require.True(t, f.Sub(f, f).Equal(newScalar(scalarZero)),
|
||||
"subtracting something from itself should give zero")
|
||||
}
|
||||
}
|
||||
|
||||
func TestScalar_Clone(t *testing.T) {
|
||||
f := newScalar(big.NewInt(1))
|
||||
g := f.Clone()
|
||||
h := f.Clone()
|
||||
assert.Equal(t, f, g, "clone output does not equal input")
|
||||
g.Add(f, f)
|
||||
assert.Equal(t, f, h, "clone does not make a copy")
|
||||
}
|
||||
|
||||
func TestScalar_Marshal(t *testing.T) {
|
||||
f := newScalar(scalarZero)
|
||||
g := newScalar(scalarZero)
|
||||
for i := 0; i < numFieldSamples; i++ {
|
||||
f.Pick(randomStreamScalar)
|
||||
observedScalar(t, f)
|
||||
data, err := f.MarshalBinary()
|
||||
require.Nil(t, err)
|
||||
err = g.UnmarshalBinary(data)
|
||||
require.Nil(t, err)
|
||||
require.True(t, g.Equal(f),
|
||||
"roundtrip through serialization should give same "+
|
||||
"result back: failed with %s", f)
|
||||
}
|
||||
marshalID := f.(*secp256k1Scalar).MarshalID()
|
||||
require.Equal(t, string(marshalID[:]), "sp256.sc")
|
||||
data := make([]byte, 33)
|
||||
require.Contains(t, f.UnmarshalBinary(data).Error(), "wrong length")
|
||||
var buf bytes.Buffer
|
||||
_, err := f.MarshalTo(&buf)
|
||||
require.NoError(t, err)
|
||||
_, err = f.UnmarshalFrom(&buf)
|
||||
require.NoError(t, err)
|
||||
}
|
||||
|
||||
func TestScalar_MulDivInv(t *testing.T) {
|
||||
f := newScalar(scalarZero)
|
||||
g := newScalar(scalarZero)
|
||||
h := newScalar(scalarZero)
|
||||
j := newScalar(scalarZero)
|
||||
k := newScalar(scalarZero)
|
||||
for i := 0; i < numFieldSamples; i++ {
|
||||
f.Pick(randomStreamScalar)
|
||||
observedScalar(t, f)
|
||||
g.Inv(f)
|
||||
h.Mul(f, g)
|
||||
require.True(t, h.Equal(newScalar(big.NewInt(1))))
|
||||
h.Div(f, f)
|
||||
require.True(t, h.Equal(newScalar(big.NewInt(1))))
|
||||
h.Div(newScalar(big.NewInt(1)), f)
|
||||
require.True(t, h.Equal(g))
|
||||
h.Pick(randomStreamScalar)
|
||||
observedScalar(t, h)
|
||||
j.Neg(j.Mul(h, f))
|
||||
k.Mul(h, k.Neg(f))
|
||||
require.True(t, j.Equal(k), "-(h*f) != h*(-f)")
|
||||
}
|
||||
}
|
||||
|
||||
func TestScalar_AllowVarTime(t *testing.T) {
|
||||
defer func() { require.Contains(t, recover(), "not constant-time!") }()
|
||||
newScalar(bigZero).(*secp256k1Scalar).AllowVarTime(false)
|
||||
}
|
||||
|
||||
func TestScalar_String(t *testing.T) {
|
||||
require.Equal(t, newScalar(bigZero).String(), "scalar{0}")
|
||||
}
|
||||
|
||||
func TestScalar_SetInt64(t *testing.T) {
|
||||
require.Equal(t, newScalar(bigZero).SetInt64(1), newScalar(big.NewInt(1)))
|
||||
require.True(t, newScalar(big.NewInt(1)).Zero().Equal(newScalar(bigZero)))
|
||||
require.Equal(t, newScalar(bigZero).One(), newScalar(big.NewInt(1)))
|
||||
}
|
||||
|
||||
func TestScalar_DivPanicsOnZeroDivisor(t *testing.T) {
|
||||
defer func() { require.Contains(t, recover(), "divide by zero") }()
|
||||
newScalar(bigZero).Div(newScalar(bigZero).One(), newScalar(bigZero))
|
||||
}
|
||||
|
||||
func TestScalar_InvPanicsOnZero(t *testing.T) {
|
||||
defer func() { require.Contains(t, recover(), "divide by zero") }()
|
||||
newScalar(bigZero).Inv(newScalar(bigZero))
|
||||
}
|
||||
|
||||
func TestScalar_SetBytes(t *testing.T) {
|
||||
u256Cardinality := zero().Lsh(big.NewInt(1), 256)
|
||||
newScalar(bigZero).(*secp256k1Scalar).int().Cmp(
|
||||
zero().Sub(u256Cardinality, GroupOrder))
|
||||
}
|
||||
|
||||
func TestScalar_IsSecp256k1Scalar(t *testing.T) {
|
||||
c := curve25519.NewBlakeSHA256Curve25519(true)
|
||||
require.False(t, IsSecp256k1Scalar(c.Scalar()))
|
||||
require.True(t, IsSecp256k1Scalar(newScalar(bigZero)))
|
||||
}
|
||||
|
||||
func TestScalar_IntToScalar(t *testing.T) {
|
||||
u256Cardinality := zero().Lsh(big.NewInt(1), 256)
|
||||
IntToScalar(u256Cardinality)
|
||||
require.Equal(t, u256Cardinality, zero().Sub(zero().Lsh(big.NewInt(1), 256),
|
||||
GroupOrder))
|
||||
}
|
||||
|
|
@ -0,0 +1,89 @@
|
|||
// Package secp256k1 is an implementation of the kyber.{Group,Point,Scalar}
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// XXX: Do not use in production until this code has been audited.
|
||||
////////////////////////////////////////////////////////////////////////////////
|
||||
// interfaces, based on btcd/btcec and kyber/group/mod
|
||||
//
|
||||
// XXX: NOT CONSTANT TIME!
|
||||
package secp256k1
|
||||
|
||||
import (
|
||||
"crypto/cipher"
|
||||
"hash"
|
||||
"io"
|
||||
"reflect"
|
||||
|
||||
"golang.org/x/crypto/sha3"
|
||||
|
||||
"go.dedis.ch/fixbuf"
|
||||
"go.dedis.ch/kyber/v3"
|
||||
"go.dedis.ch/kyber/v3/util/random"
|
||||
"go.dedis.ch/kyber/v3/xof/blake2xb"
|
||||
)
|
||||
|
||||
// SuiteSecp256k1 implements some basic functionalities such as Group, HashFactory,
|
||||
// and XOFFactory.
|
||||
type SuiteSecp256k1 struct {
|
||||
Secp256k1
|
||||
r cipher.Stream
|
||||
}
|
||||
|
||||
// Hash returns a newly instantiated keccak hash function.
|
||||
func (s *SuiteSecp256k1) Hash() hash.Hash {
|
||||
return sha3.NewLegacyKeccak256()
|
||||
}
|
||||
|
||||
// XOF returns an XOR function, implemented via the Blake2b hash.
|
||||
//
|
||||
// This should only be used for generating secrets, so there is no need to make
|
||||
// it cheap to compute on-chain.
|
||||
func (s *SuiteSecp256k1) XOF(key []byte) kyber.XOF {
|
||||
return blake2xb.New(key)
|
||||
}
|
||||
|
||||
// Read implements the Encoding interface function, and reads a series of objs from r
|
||||
// The objs must all be pointers
|
||||
func (s *SuiteSecp256k1) Read(r io.Reader, objs ...interface{}) error {
|
||||
return fixbuf.Read(r, s, objs...)
|
||||
}
|
||||
|
||||
// Write implements the Encoding interface, and writes the objs to r using their
|
||||
// built-in binary serializations. Supports Points, Scalars, fixed-length data
|
||||
// types supported by encoding/binary/Write(), and structs, arrays, and slices
|
||||
// containing these types.
|
||||
func (s *SuiteSecp256k1) Write(w io.Writer, objs ...interface{}) error {
|
||||
return fixbuf.Write(w, objs)
|
||||
}
|
||||
|
||||
var aScalar kyber.Scalar
|
||||
var tScalar = reflect.TypeOf(aScalar)
|
||||
var aPoint kyber.Point
|
||||
var tPoint = reflect.TypeOf(aPoint)
|
||||
|
||||
// New implements the kyber.Encoding interface, and returns a new element of
|
||||
// type t, which can be a Point or a Scalar
|
||||
func (s *SuiteSecp256k1) New(t reflect.Type) interface{} {
|
||||
switch t {
|
||||
case tScalar:
|
||||
return s.Scalar()
|
||||
case tPoint:
|
||||
return s.Point()
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
// RandomStream returns a cipher.Stream that returns a key stream
|
||||
// from crypto/rand.
|
||||
func (s *SuiteSecp256k1) RandomStream() cipher.Stream {
|
||||
if s.r != nil {
|
||||
return s.r
|
||||
}
|
||||
return random.New()
|
||||
}
|
||||
|
||||
// NewBlakeKeccackSecp256k1 returns a cipher suite based on package
|
||||
// go.dedis.ch/kyber/xof/blake2xb, SHA-256, and the secp256k1 curve. It
|
||||
// produces cryptographically secure random numbers via package crypto/rand.
|
||||
func NewBlakeKeccackSecp256k1() *SuiteSecp256k1 {
|
||||
return new(SuiteSecp256k1)
|
||||
}
|
||||
|
|
@ -0,0 +1,16 @@
|
|||
package secp256k1
|
||||
|
||||
import (
|
||||
"encoding/hex"
|
||||
"testing"
|
||||
|
||||
"github.com/stretchr/testify/require"
|
||||
)
|
||||
|
||||
func TestSuite(t *testing.T) {
|
||||
s := NewBlakeKeccackSecp256k1()
|
||||
emptyHashAsHex := hex.EncodeToString(s.Hash().Sum(nil))
|
||||
require.Equal(t, emptyHashAsHex,
|
||||
"c5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470")
|
||||
_ = s.RandomStream()
|
||||
}
|
||||
Loading…
Reference in New Issue