extract secret from final signature

Author: keithsue

x/lending/keeper/msg_server.go

@@ -334,12 +334,21 @@ func (m msgServer) Close(goCtx context.Context, msg *types.MsgClose) (*types.Msg
 		return nil, types.ErrInvalidRepayment
 	}
 
-	repay := m.GetRepayment(ctx, msg.LoanId)
+	repayment := m.GetRepayment(ctx, msg.LoanId)
+	if len(repayment.DcaAdaptorSignature) == 0 {
+		return nil, types.ErrRepaymentAdaptorSigDoesNotExist
+	}
+
+	sigBytes, _ := hex.DecodeString(msg.Signature)
+	adaptorSigBytes, _ := hex.DecodeString(repayment.DcaAdaptorSignature)
 
 	// extract secret from signature
-	secret := msg.Signature + repay.RepayAdaptorPoint // fix it later.
+	secret := adaptor.Extract(sigBytes, adaptorSigBytes)
+	if len(secret) == 0 {
+		return nil, types.ErrInvalidSignature
+	}
 
-	if types.AdaptorPoint(secret) != repay.RepayAdaptorPoint {
+	if types.AdaptorPoint(secret) != repayment.RepayAdaptorPoint {
 		return nil, types.ErrInvalidRepaymentSecret
 	}
 
@@ -355,7 +364,7 @@ func (m msgServer) Close(goCtx context.Context, msg *types.MsgClose) (*types.Msg
 
 	m.EmitEvent(ctx, msg.Relayer,
 		sdk.NewAttribute("loan_id", loan.VaultAddress),
-		sdk.NewAttribute("payment_secret", secret),
+		sdk.NewAttribute("payment_secret", hex.EncodeToString(secret)),
 	)
 
 	return &types.MsgCloseResponse{}, nil

x/lending/types/errors.go

@@ -43,6 +43,9 @@ var (
 	ErrInvalidRepaymentTx               = errorsmod.Register(ModuleName, 6003, "invalid repayment tx")
 	ErrInvalidRepaymentSecret           = errorsmod.Register(ModuleName, 6004, "invalid repayment secret")
 	ErrRepaymentAdaptorSigAlreadyExists = errorsmod.Register(ModuleName, 6005, "repayment adaptor signature already exists")
-	ErrInvalidAdaptorSignature          = errorsmod.Register(ModuleName, 6006, "invalid adaptor signature")
-	ErrEmptyLoanId                      = errorsmod.Register(ModuleName, 6007, "empty loan id")
+	ErrRepaymentAdaptorSigDoesNotExist  = errorsmod.Register(ModuleName, 6006, "repayment adaptor signature does not exist")
+	ErrInvalidAdaptorSignature          = errorsmod.Register(ModuleName, 6007, "invalid adaptor signature")
+	ErrEmptyLoanId                      = errorsmod.Register(ModuleName, 6008, "empty loan id")
+
+	ErrInvalidSignature = errorsmod.Register(ModuleName, 7001, "invalid signature")
 )

x/lending/types/taproot.go

@@ -26,11 +26,8 @@ func HashLoanSecret(secret string) string {
 }
 
 // AdaptorPoint gets the corresponding adaptor point from the given secret
-// Assume that the secret is a valid hex string
-func AdaptorPoint(secret string) string {
-	secretBytes, _ := hex.DecodeString(secret)
-
-	return hex.EncodeToString(adaptor.SecretToPubKey(secretBytes))
+func AdaptorPoint(secret []byte) string {
+	return hex.EncodeToString(adaptor.SecretToPubKey(secret))
 }
 
 func GetTaprootAddress(script []byte) (*btcutil.AddressTaproot, error) {