Files
zeekay f7b136528d round: pointer receivers on trivial round methods
VerifyMessage/StoreMessage/MessageContent/Number/BroadcastContent on
round structs were value receivers. Go FAQ: "if any method on T takes
*T, all methods should take *T." Finalize already takes *T (it mutates
round state) so the others should too. Aligns the method set, removes
silent struct-copies on every dispatch, and prevents future drift
where a value-receiver method accidentally observes pre-Finalize
state. No behavior change — all current methods are no-ops or return
constants.

Touched: round.Abort, round.Output, all CMP keygen/presign/sign rounds,
all Doerner keygen/sign rounds, all FROST keygen/sign rounds, xor
example. Build + vet clean; CMP/FROST/Doerner -race tests PASS.
2026-06-01 00:07:58 -07:00

107 lines
3.3 KiB
Go

package keygen
import (
"errors"
"github.com/luxfi/threshold/internal/ot"
"github.com/luxfi/threshold/internal/params"
"github.com/luxfi/threshold/internal/round"
"github.com/luxfi/threshold/pkg/hash"
"github.com/luxfi/threshold/pkg/math/curve"
zksch "github.com/luxfi/threshold/pkg/zk/sch"
)
// message2R is the message sent by the Receiver at the start of the second round.
type message2R struct {
// Decommit reveals the value that we committed to earlier.
Decommit hash.Decommitment
// ChainKeyDecommit is the decommitment to our chain key
ChainKeyDecommit hash.Decommitment
// RefreshDecommit is the decommitment to our refresh value
RefreshDecommit hash.Decommitment
// ChainKey is our contribution to the chain key.
ChainKey []byte
// PublicShare is our secret share times the group generator.
PublicShare curve.Point
// RefreshScalar is our refresh to the secret shares.
RefreshScalar curve.Scalar
// Proof is a proof of knowledge of the discrete logarithm of PublicShare.
Proof *zksch.Proof
OtMsg *ot.CorreOTSetupReceiveRound2Message
}
func (message2R) RoundNumber() round.Number { return 2 }
type round2R struct {
*round1R
// proof is a proof of knowledge for the discrete logarithm of our public share.
proof *zksch.Proof
// decommit is the decommitment to our first commitment
decommit hash.Decommitment
// chainKeyDecommit is the decommitment to our chain key commitment
chainKeyDecommit hash.Decommitment
// refreshDecommit is the decommitment to our refresh commitment
refreshDecommit hash.Decommitment
// refreshScalar is our contribution to refreshing the shares
refreshScalar curve.Scalar
// ourChainKey is our contribution to the chain key
ourChainKey []byte
// chainKey is our collective chain key
chainKey []byte
otMsg *ot.CorreOTSetupReceiveRound2Message
}
func (r *round2R) VerifyMessage(msg round.Message) error {
body, ok := msg.Content.(*message1S)
if !ok || body == nil {
return round.ErrInvalidContent
}
if body.Proof == nil || body.PublicShare == nil || body.RefreshScalar == nil || body.OtMsg == nil {
return round.ErrNilFields
}
if !body.Proof.Verify(r.Hash(), body.PublicShare, nil) {
return errors.New("invalid Schnorr proof")
}
if len(body.ChainKey) != params.SecBytes {
return errors.New("chain key too short")
}
return nil
}
func (r *round2R) StoreMessage(msg round.Message) (err error) {
body := msg.Content.(*message1S)
r.otMsg, err = r.receiver.Round2(body.OtMsg)
if err != nil {
return err
}
if !r.refresh {
r.public = r.publicShare.Add(body.PublicShare)
}
r.chainKey = body.ChainKey
for i := 0; i < len(r.chainKey) && i < len(r.ourChainKey); i++ {
r.chainKey[i] ^= r.ourChainKey[i]
}
r.secretShare = r.Group().NewScalar().Set(r.secretShare).Add(r.refreshScalar).Sub(body.RefreshScalar)
return nil
}
func (r *round2R) Finalize(out chan<- *round.Message) (round.Session, error) {
if err := r.SendMessage(out, &message2R{r.decommit, r.chainKeyDecommit, r.refreshDecommit, r.ourChainKey, r.publicShare, r.refreshScalar, r.proof, r.otMsg}, ""); err != nil {
return r, err
}
return &round3R{round2R: r}, nil
}
func (r *round2R) MessageContent() round.Content {
group := r.Group()
return &message1S{
PublicShare: group.NewPoint(),
RefreshScalar: group.NewScalar(),
Proof: zksch.EmptyProof(group),
}
}
func (*round2R) Number() round.Number {
return 2
}