chore: adds unsafeSignEOTS for testing double signing (#193)

CHANGELOG.md

@@ -45,6 +45,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 * [#184](https://github.com/babylonlabs-io/finality-provider/pull/184) eots manager sign record store
 * [#189](https://github.com/babylonlabs-io/finality-provider/pull/189) Remove `fpd register-finality-provider` cmd
 * [#190](https://github.com/babylonlabs-io/finality-provider/pull/190) Benchmark pub rand
+* [#193](https://github.com/babylonlabs-io/finality-provider/pull/193) adds unsafeSignEOTS for e2e tests
 * [#195](https://github.com/babylonlabs-io/finality-provider/pull/195) Not block unjailing
 
 ### Bug Fixes

eotsmanager/client/rpcclient.go

@@ -118,6 +118,25 @@ func (c *EOTSManagerGRpcClient) SignEOTS(uid, chaiID, msg []byte, height uint64,
 	return &s, nil
 }
 
+func (c *EOTSManagerGRpcClient) UnsafeSignEOTS(uid, chaiID, msg []byte, height uint64, passphrase string) (*btcec.ModNScalar, error) {
+	req := &proto.SignEOTSRequest{
+		Uid:        uid,
+		ChainId:    chaiID,
+		Msg:        msg,
+		Height:     height,
+		Passphrase: passphrase,
+	}
+	res, err := c.client.UnsafeSignEOTS(context.Background(), req)
+	if err != nil {
+		return nil, err
+	}
+
+	var s btcec.ModNScalar
+	s.SetByteSlice(res.Sig)
+
+	return &s, nil
+}
+
 func (c *EOTSManagerGRpcClient) SignSchnorrSig(uid, msg []byte, passphrase string) (*schnorr.Signature, error) {
 	req := &proto.SignSchnorrSigRequest{Uid: uid, Msg: msg, Passphrase: passphrase}
 	res, err := c.client.SignSchnorrSig(context.Background(), req)

eotsmanager/eotsmanager.go

@@ -28,9 +28,15 @@ type EOTSManager interface {
 	// SignEOTS signs an EOTS using the private key of the finality provider and the corresponding
 	// secret randomness of the given chain at the given height
 	// It fails if the finality provider does not exist or there's no randomness committed to the given height
-	// or passPhrase is incorrect
+	// or passPhrase is incorrect. Has built-in anti-slashing mechanism to ensure signature
+	// for the same height will not be signed twice.
 	SignEOTS(uid []byte, chainID []byte, msg []byte, height uint64, passphrase string) (*btcec.ModNScalar, error)
 
+	// UnsafeSignEOTS should only be used in e2e tests for demonstration purposes.
+	// Does not offer double sign protection.
+	// Use SignEOTS for real operations.
+	UnsafeSignEOTS(uid []byte, chainID []byte, msg []byte, height uint64, passphrase string) (*btcec.ModNScalar, error)
+
 	// SignSchnorrSig signs a Schnorr signature using the private key of the finality provider
 	// It fails if the finality provider does not exist or the message size is not 32 bytes
 	// or passPhrase is incorrect

eotsmanager/localmanager.go

@@ -205,6 +205,14 @@ func (lm *LocalEOTSManager) SignEOTS(fpPk []byte, chainID []byte, msg []byte, he
 			return &s, nil
 		}
 
+		lm.logger.Error(
+			"double sign error protection",
+			zap.String("fp", hex.EncodeToString(fpPk)),
+			zap.String("msg", hex.EncodeToString(msg)),
+			zap.Uint64("height", height),
+			zap.String("chainID", string(chainID)),
+		)
+
 		return nil, eotstypes.ErrDoubleSign
 	}
 
@@ -235,6 +243,25 @@ func (lm *LocalEOTSManager) SignEOTS(fpPk []byte, chainID []byte, msg []byte, he
 	return signedBytes, nil
 }
 
+// UnsafeSignEOTS should only be used in e2e test to demonstrate double sign
+func (lm *LocalEOTSManager) UnsafeSignEOTS(fpPk []byte, chainID []byte, msg []byte, height uint64, passphrase string) (*btcec.ModNScalar, error) {
+	privRand, _, err := lm.getRandomnessPair(fpPk, chainID, height, passphrase)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get private randomness: %w", err)
+	}
+
+	privKey, err := lm.getEOTSPrivKey(fpPk, passphrase)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get EOTS private key: %w", err)
+	}
+
+	// Update metrics
+	lm.metrics.IncrementEotsFpTotalEotsSignCounter(hex.EncodeToString(fpPk))
+	lm.metrics.SetEotsFpLastEotsSignHeight(hex.EncodeToString(fpPk), float64(height))
+
+	return eots.Sign(privKey, privRand, msg)
+}
+
 func (lm *LocalEOTSManager) SignSchnorrSig(fpPk []byte, msg []byte, passphrase string) (*schnorr.Signature, error) {
 	privKey, err := lm.getEOTSPrivKey(fpPk, passphrase)
 	if err != nil {

eotsmanager/proto/eotsmanager.proto

@@ -23,6 +23,10 @@ service EOTSManager {
   rpc SignEOTS (SignEOTSRequest)
       returns (SignEOTSResponse);
 
+  // UnsafeSignEOTS used only for testing purpose. Use SignEOTS for real operations
+  rpc UnsafeSignEOTS (SignEOTSRequest)
+      returns (SignEOTSResponse);
+
   // SignSchnorrSig signs a Schnorr sig with the EOTS private key
   rpc SignSchnorrSig (SignSchnorrSigRequest)
       returns (SignSchnorrSigResponse);

eotsmanager/service/rpcserver.go

@@ -98,6 +98,19 @@ func (r *rpcServer) SignEOTS(_ context.Context, req *proto.SignEOTSRequest) (
 	return &proto.SignEOTSResponse{Sig: sigBytes[:]}, nil
 }
 
+// UnsafeSignEOTS only used for testing purposes. Doesn't offer slashing protection!
+func (r *rpcServer) UnsafeSignEOTS(_ context.Context, req *proto.SignEOTSRequest) (
+	*proto.SignEOTSResponse, error) {
+	sig, err := r.em.UnsafeSignEOTS(req.Uid, req.ChainId, req.Msg, req.Height, req.Passphrase)
+	if err != nil {
+		return nil, err
+	}
+
+	sigBytes := sig.Bytes()
+
+	return &proto.SignEOTSResponse{Sig: sigBytes[:]}, nil
+}
+
 // SignSchnorrSig signs a Schnorr sig with the EOTS private key
 func (r *rpcServer) SignSchnorrSig(_ context.Context, req *proto.SignSchnorrSigRequest) (
 	*proto.SignSchnorrSigResponse, error) {

finality-provider/cmd/fpd/daemon/daemon_commands.go

@@ -359,6 +359,8 @@ func CommandAddFinalitySig() *cobra.Command {
 	}
 	cmd.Flags().String(fpdDaemonAddressFlag, defaultFpdDaemonAddress, "The RPC server address of fpd")
 	cmd.Flags().String(appHashFlag, defaultAppHashStr, "The last commit hash of the chain block")
+	cmd.Flags().Bool(checkDoubleSignFlag, true, "If 'true', uses anti-slashing protection when doing EOTS sign")
+
 	return cmd
 }
 
@@ -383,6 +385,11 @@ func runCommandAddFinalitySig(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("failed to read flag %s: %w", appHashFlag, err)
 	}
 
+	checkDoubleSign, err := flags.GetBool(checkDoubleSignFlag)
+	if err != nil {
+		return fmt.Errorf("failed to read flag %s: %w", checkDoubleSignFlag, err)
+	}
+
 	client, cleanUp, err := dc.NewFinalityProviderServiceGRpcClient(daemonAddress)
 	if err != nil {
 		return err
@@ -398,7 +405,7 @@ func runCommandAddFinalitySig(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	res, err := client.AddFinalitySignature(context.Background(), fpPk.MarshalHex(), blkHeight, appHash)
+	res, err := client.AddFinalitySignature(context.Background(), fpPk.MarshalHex(), blkHeight, appHash, checkDoubleSign)
 	if err != nil {
 		return err
 	}

finality-provider/cmd/fpd/daemon/flags.go

@@ -11,6 +11,7 @@ const (
 	hdPathFlag           = "hd-path"
 	chainIDFlag          = "chain-id"
 	signedFlag           = "signed"
+	checkDoubleSignFlag  = "check-double-sign"
 
 	// flags for description
 	monikerFlag         = "moniker"