chore: adds unsafeSignEOTS for testing double signing

CHANGELOG.md

@@ -44,6 +44,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 * [#182](https://github.com/babylonlabs-io/finality-provider/pull/182) Remove fp manager
 * [#184](https://github.com/babylonlabs-io/finality-provider/pull/184) eots manager sign record store
 * [#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
 
 ### 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

@@ -31,6 +31,9 @@ type EOTSManager interface {
 	// or passPhrase is incorrect
 	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. 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

@@ -235,6 +235,25 @@ 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/service/fp_instance.go

@@ -695,8 +695,18 @@ func (fp *FinalityProviderInstance) TestSubmitFinalitySignatureAndExtractPrivKey
 		return nil, nil, fmt.Errorf("failed to get public randomness inclusion proof: %w", err)
 	}
 
+	unsafeSign := func(b *types.BlockInfo) (*bbntypes.SchnorrEOTSSig, error) {
+		msgToSign := getMsgToSignForVote(b.Height, b.Hash)
+		sig, err := fp.em.UnsafeSignEOTS(fp.btcPk.MustMarshal(), fp.GetChainID(), msgToSign, b.Height, fp.passphrase)
+		if err != nil {
+			return nil, fmt.Errorf("failed to sign EOTS: %w", err)
+		}
+
+		return bbntypes.NewSchnorrEOTSSigFromModNScalar(sig), nil
+	}
+
 	// sign block
-	eotsSig, err := fp.signFinalitySig(b)
+	eotsSig, err := unsafeSign(b)
 	if err != nil {
 		return nil, nil, err
 	}

itest/e2e_test.go

@@ -98,14 +98,11 @@ func TestDoubleSigning(t *testing.T) {
 		Height: finalizedBlocks[0].Height,
 		Hash:   datagen.GenRandomByteArray(r, 32),
 	}
-	_, _, err = fpIns.TestSubmitFinalitySignatureAndExtractPrivKey(b)
-	require.Error(t, err)
-
-	// todo(lazar): implement UnsafeSignEOTS, containing logic without double sign protection
-	//require.NoError(t, err)
-	//require.NotNil(t, extractedKey)
-	//localKey := tm.GetFpPrivKey(t, fpIns.GetBtcPkBIP340().MustMarshal())
-	//require.True(t, localKey.Key.Equals(&extractedKey.Key) || localKey.Key.Negate().Equals(&extractedKey.Key))
+	_, extractedKey, err = fpIns.TestSubmitFinalitySignatureAndExtractPrivKey(b)
+	require.NoError(t, err)
+	require.NotNil(t, extractedKey)
+	localKey := tm.GetFpPrivKey(t, fpIns.GetBtcPkBIP340().MustMarshal())
+	require.True(t, localKey.Key.Equals(&extractedKey.Key) || localKey.Key.Negate().Equals(&extractedKey.Key))
 
 	t.Logf("the equivocation attack is successful")
 }