Unexport payment signer (#847)

core/auth/payment_signer.go

@@ -3,45 +3,46 @@ package auth
 import (
 	"crypto/ecdsa"
 	"fmt"
-	"log"
 
 	commonpb "github.com/Layr-Labs/eigenda/api/grpc/common"
 	"github.com/Layr-Labs/eigenda/core"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
 )
 
-type PaymentSigner struct {
+type paymentSigner struct {
 	PrivateKey *ecdsa.PrivateKey
 }
 
-var _ core.PaymentSigner = &PaymentSigner{}
-
-func NewPaymentSigner(privateKeyHex string) *PaymentSigner {
+var _ core.PaymentSigner = &paymentSigner{}
 
+func NewPaymentSigner(privateKeyHex string) (*paymentSigner, error) {
+	if len(privateKeyHex) == 0 {
+		return nil, fmt.Errorf("private key cannot be empty")
+	}
 	privateKeyBytes := common.FromHex(privateKeyHex)
 	privateKey, err := crypto.ToECDSA(privateKeyBytes)
 	if err != nil {
-		log.Fatalf("Failed to parse private key: %v", err)
+		return nil, fmt.Errorf("failed to convert hex to ECDSA private key: %w", err)
 	}
 
-	return &PaymentSigner{
+	return &paymentSigner{
 		PrivateKey: privateKey,
-	}
+	}, nil
 }
 
 // SignBlobPayment signs the payment header and returns the signature
-func (s *PaymentSigner) SignBlobPayment(header *commonpb.PaymentHeader) ([]byte, error) {
+func (s *paymentSigner) SignBlobPayment(header *commonpb.PaymentHeader) ([]byte, error) {
 	header.AccountId = s.GetAccountID()
 	pm := core.ConvertPaymentHeader(header)
 	hash, err := pm.Hash()
 	if err != nil {
-		return nil, fmt.Errorf("failed to hash payment header: %v", err)
+		return nil, fmt.Errorf("failed to hash payment header: %w", err)
 	}
 
 	sig, err := crypto.Sign(hash[:], s.PrivateKey)
 	if err != nil {
-		return nil, fmt.Errorf("failed to sign hash: %v", err)
+		return nil, fmt.Errorf("failed to sign hash: %w", err)
 	}
 
 	return sig, nil
@@ -62,35 +63,39 @@ func (s *NoopPaymentSigner) GetAccountID() string {
 }
 
 // VerifyPaymentSignature verifies the signature against the payment metadata
-func VerifyPaymentSignature(paymentHeader *commonpb.PaymentHeader, paymentSignature []byte) bool {
+func VerifyPaymentSignature(paymentHeader *commonpb.PaymentHeader, paymentSignature []byte) error {
 	pm := core.ConvertPaymentHeader(paymentHeader)
 	hash, err := pm.Hash()
 	if err != nil {
-		return false
+		return fmt.Errorf("failed to hash payment header: %w", err)
 	}
 
 	recoveredPubKey, err := crypto.SigToPub(hash[:], paymentSignature)
 	if err != nil {
-		log.Printf("Failed to recover public key from signature: %v\n", err)
-		return false
+		return fmt.Errorf("failed to recover public key from signature: %w", err)
 	}
 
 	recoveredAddress := crypto.PubkeyToAddress(*recoveredPubKey)
 	accountId := common.HexToAddress(paymentHeader.AccountId)
 	if recoveredAddress != accountId {
-		log.Printf("Signature address %s does not match account id %s\n", recoveredAddress.Hex(), accountId.Hex())
-		return false
+		return fmt.Errorf("signature address %s does not match account id %s", recoveredAddress.Hex(), accountId.Hex())
 	}
 
-	return crypto.VerifySignature(
+	ok := crypto.VerifySignature(
 		crypto.FromECDSAPub(recoveredPubKey),
 		hash[:],
 		paymentSignature[:len(paymentSignature)-1], // Remove recovery ID
 	)
+
+	if !ok {
+		return fmt.Errorf("invalid signature")
+	}
+
+	return nil
 }
 
 // GetAccountID returns the Ethereum address of the signer
-func (s *PaymentSigner) GetAccountID() string {
+func (s *paymentSigner) GetAccountID() string {
 	publicKey := crypto.FromECDSAPub(&s.PrivateKey.PublicKey)
 	hash := crypto.Keccak256(publicKey[1:])
 

core/auth/payment_signer_test.go

@@ -16,7 +16,8 @@ func TestPaymentSigner(t *testing.T) {
 	require.NoError(t, err)
 
 	privateKeyHex := hex.EncodeToString(crypto.FromECDSA(privateKey))
-	signer := auth.NewPaymentSigner(privateKeyHex)
+	signer, err := auth.NewPaymentSigner(privateKeyHex)
+	require.NoError(t, err)
 
 	t.Run("SignBlobPayment", func(t *testing.T) {
 		header := &commonpb.PaymentHeader{
@@ -30,8 +31,8 @@ func TestPaymentSigner(t *testing.T) {
 		assert.NotEmpty(t, signature)
 
 		// Verify the signature
-		isValid := auth.VerifyPaymentSignature(header, signature)
-		assert.True(t, isValid)
+		err = auth.VerifyPaymentSignature(header, signature)
+		assert.NoError(t, err)
 	})
 
 	t.Run("VerifyPaymentSignature_InvalidSignature", func(t *testing.T) {
@@ -43,8 +44,8 @@ func TestPaymentSigner(t *testing.T) {
 
 		// Create an invalid signature
 		invalidSignature := make([]byte, 65)
-		isValid := auth.VerifyPaymentSignature(header, invalidSignature)
-		assert.False(t, isValid)
+		err = auth.VerifyPaymentSignature(header, invalidSignature)
+		assert.Error(t, err)
 	})
 
 	t.Run("VerifyPaymentSignature_ModifiedHeader", func(t *testing.T) {
@@ -60,8 +61,8 @@ func TestPaymentSigner(t *testing.T) {
 		// Modify the header after signing
 		header.BinIndex = 2
 
-		isValid := auth.VerifyPaymentSignature(header, signature)
-		assert.False(t, isValid)
+		err = auth.VerifyPaymentSignature(header, signature)
+		assert.Error(t, err)
 	})
 }
 

disperser/apiserver/server.go

@@ -329,9 +329,6 @@ func (s *DispersalServer) DispersePaidBlob(ctx context.Context, req *pb.Disperse
 	cumulativePayment := new(big.Int).SetBytes(req.PaymentHeader.CumulativePayment)
 	//todo: before disperse blob, validate the signature
 	signature := req.PaymentSignature
-	if !auth.VerifyPaymentSignature(req.GetPaymentHeader(), signature) {
-		return nil, api.NewErrorInvalidArg("payment signature is invalid")
-	}
 	if err != nil {
 		for _, quorumID := range req.QuorumNumbers {
 			s.metrics.HandleFailedRequest(codes.InvalidArgument.String(), fmt.Sprint(quorumID), len(req.GetData()), "DispersePaidBlob")
@@ -340,6 +337,10 @@ func (s *DispersalServer) DispersePaidBlob(ctx context.Context, req *pb.Disperse
 		return nil, api.NewErrorInvalidArg(err.Error())
 	}
 
+	if err = auth.VerifyPaymentSignature(req.GetPaymentHeader(), signature); err != nil {
+		return nil, api.NewErrorInvalidArg("payment signature is invalid")
+	}
+
 	paymentHeader := core.PaymentMetadata{
 		AccountID:         blob.RequestHeader.AccountID,
 		BinIndex:          binIndex,
@@ -1114,8 +1115,8 @@ func (s *DispersalServer) validatePaidRequestAndGetBlob(ctx context.Context, req
 	seenQuorums := make(map[uint8]struct{})
 
 	// TODO: validate payment signature against payment metadata
-	if !auth.VerifyPaymentSignature(req.GetPaymentHeader(), req.GetPaymentSignature()) {
-		return nil, fmt.Errorf("payment signature is invalid")
+	if err = auth.VerifyPaymentSignature(req.GetPaymentHeader(), req.GetPaymentSignature()); err != nil {
+		return nil, fmt.Errorf("payment signature is invalid: %w", err)
 	}
 	// Unlike regular blob dispersal request validation, there's no check with required quorums
 	// Because Reservation has their specific quorum requirements, and on-demand is only allowed and paid to the required quorums.