Ensure signing and verifying modifies no input

f3/api.go

@@ -47,23 +47,23 @@ type Clock interface {
 type Signer interface {
 	// Signs a message for the given sender ID.
 	Sign(sender ActorID, msg []byte) []byte
-	// Verifies a signature for the given sender ID.
-	Verify(sender ActorID, msg, sig []byte) bool
 }
 
-type Aggregator interface {
+type Verifier interface {
+	// Verifies a signature for the given sender ID.
+	Verify(pubKey PubKey, msg, sig []byte) bool
 	// Aggregates signatures from a participant to an existing signature.
-	Aggregate(sig []byte, aggSignature []byte) []byte
+	Aggregate(sig [][]byte, aggSignature []byte) []byte
 	// VerifyAggregate verifies an aggregate signature.
-	VerifyAggregate(payload, aggSig []byte, signers [][]byte) bool
+	VerifyAggregate(payload, aggSig []byte, signers []PubKey) bool
 }
 
 // Participant interface to the host system resources.
 type Host interface {
 	Network
 	Clock
 	Signer
-	Aggregator
+	Verifier
 
 	// Logs a message at the "logic" level
 	Log(format string, args ...interface{})

f3/granite.go

@@ -220,6 +220,7 @@ func (i *instance) receiveOne(msg *GMessage) error {
 	if i.phase == TERMINATED {
 		return nil // No-op
 	}
+	round := i.roundState(msg.Round)
 
 	// Drop any messages that can never be valid.
 	if !i.isValid(msg) {
@@ -234,7 +235,6 @@ func (i *instance) receiveOne(msg *GMessage) error {
 		return nil
 	}
 
-	round := i.roundState(msg.Round)
 	switch msg.Step {
 	case QUALITY:
 		// Receive each prefix of the proposal independently.
@@ -259,6 +259,7 @@ func (i *instance) receiveOne(msg *GMessage) error {
 	// Try to complete the current phase.
 	// Every COMMIT phase stays open to new messages even after the protocol moves on to
 	// a new round. Late-arriving COMMITS can still (must) cause a local decision, *in that round*.
+
 	if msg.Step == COMMIT && i.phase != DECIDE {
 		return i.tryCommit(msg.Round)
 	}
@@ -293,16 +294,20 @@ func (i *instance) isValid(msg *GMessage) bool {
 		i.log("sender with zero power or not in power table")
 		return false
 	}
+
+	_, pubKey := i.powerTable.Get(msg.Sender)
+
 	if !(msg.Value.IsZero() || msg.Value.HasBase(i.input.Base())) {
 		i.log("unexpected base %s", &msg.Value)
 		return false
 	}
 	if msg.Step == QUALITY {
 		return msg.Round == 0 && !msg.Value.IsZero()
 	} else if msg.Step == CONVERGE {
+
 		if msg.Round == 0 ||
 			msg.Value.IsZero() ||
-			!i.vrf.VerifyTicket(i.beacon, i.instanceID, msg.Round, msg.Sender, msg.Ticket) {
+			!i.vrf.VerifyTicket(i.beacon, i.instanceID, msg.Round, pubKey, msg.Ticket) {
 			return false
 		}
 	} else if msg.Step == DECIDE {
@@ -311,7 +316,7 @@ func (i *instance) isValid(msg *GMessage) bool {
 	}
 
 	sigPayload := SignaturePayload(msg.Instance, msg.Round, msg.Step, msg.Value)
-	if !i.host.Verify(msg.Sender, sigPayload, msg.Signature) {
+	if !i.host.Verify(pubKey, sigPayload, msg.Signature) {
 		i.log("invalid signature on %v", msg)
 		return false
 	}
@@ -462,6 +467,7 @@ func (i *instance) tryCommit(round uint32) error {
 			}
 
 		}
+
 		i.beginNextRound()
 	}
 

f3/powertable.go

@@ -11,7 +11,7 @@ import (
 type PowerEntry struct {
 	ID     ActorID
 	Power  *StoragePower
-	PubKey []byte
+	PubKey PubKey
 }
 
 // PowerTable maps ActorID to a unique index in the range [0, len(powerTable.Entries)).

f3/types.go

@@ -9,6 +9,8 @@ type ActorID uint64
 
 type StoragePower = big.Int
 
+type PubKey []byte
+
 // Creates a new StoragePower struct with a specific value and returns the result
 func NewStoragePower(value int64) *StoragePower {
 	return new(big.Int).SetInt64(value)

f3/vrf.go

@@ -20,26 +20,28 @@ type VRFTicketSource interface {
 }
 
 type VRFTicketVerifier interface {
-	VerifyTicket(beacon []byte, instance uint32, round uint32, signer ActorID, ticket Ticket) bool
+	VerifyTicket(beacon []byte, instance uint32, round uint32, signer PubKey, ticket Ticket) bool
 }
 
 // VRF used for the CONVERGE step of GossiPBFT.
 type VRF struct {
-	signer Signer
+	signer   Signer
+	verifier Verifier
 }
 
-func NewVRF(signer Signer) *VRF {
+func NewVRF(signer Signer, verifier Verifier) *VRF {
 	return &VRF{
-		signer: signer,
+		signer:   signer,
+		verifier: verifier,
 	}
 }
 
 func (f *VRF) MakeTicket(beacon []byte, instance uint32, round uint32, signer ActorID) Ticket {
 	return f.signer.Sign(signer, f.serializeSigInput(beacon, instance, round))
 }
 
-func (f *VRF) VerifyTicket(beacon []byte, instance uint32, round uint32, signer ActorID, ticket Ticket) bool {
-	return f.signer.Verify(signer, f.serializeSigInput(beacon, instance, round), ticket)
+func (f *VRF) VerifyTicket(beacon []byte, instance uint32, round uint32, signer PubKey, ticket Ticket) bool {
+	return f.verifier.Verify(signer, f.serializeSigInput(beacon, instance, round), ticket)
 }
 
 // Serializes the input to the VRF signature for the CONVERGE step of GossiPBFT.