lndclient: expose VerifyMessage RPC

lndclient/signer_client.go

@@ -20,6 +20,12 @@ type SignerClient interface {
 	// locator. The returned signature is fixed-size LN wire format encoded.
 	SignMessage(ctx context.Context, msg []byte,
 		locator keychain.KeyLocator) ([]byte, error)
+
+	// VerifyMessage verifies a signature over a message using the public
+	// key provided. The signature must be fixed-size LN wire format
+	// encoded.
+	VerifyMessage(ctx context.Context, msg, sig []byte, pubkey [33]byte) (
+		bool, error)
 }
 
 type signerClient struct {
@@ -124,3 +130,25 @@ func (s *signerClient) SignMessage(ctx context.Context, msg []byte,
 
 	return resp.Signature, nil
 }
+
+// VerifyMessage verifies a signature over a message using the public key
+// provided. The signature must be fixed-size LN wire format encoded.
+func (s *signerClient) VerifyMessage(ctx context.Context, msg, sig []byte,
+	pubkey [33]byte) (bool, error) {
+
+	rpcCtx, cancel := context.WithTimeout(ctx, rpcTimeout)
+	defer cancel()
+
+	rpcIn := &signrpc.VerifyMessageReq{
+		Msg:       msg,
+		Signature: sig,
+		Pubkey:    pubkey[:],
+	}
+
+	rpcCtx = s.signerMac.WithMacaroonAuth(rpcCtx)
+	resp, err := s.client.VerifyMessage(rpcCtx, rpcIn)
+	if err != nil {
+		return false, err
+	}
+	return resp.Valid, nil
+}

test/lnd_services_mock.go

@@ -18,7 +18,8 @@ var (
 	testStartingHeight = int32(600)
 	testNodePubkey     = "03f5374b16f0b1f1b49101de1b9d89e0b460bc57ce9c2f9" +
 		"132b73dfc76d3704daa"
-	testSignature = []byte{55, 66, 77, 88, 99}
+	testSignature    = []byte{55, 66, 77, 88, 99}
+	testSignatureMsg = "test"
 )
 
 // NewMockLnd returns a new instance of LndMockServices that can be used in unit
@@ -61,6 +62,7 @@ func NewMockLnd() *LndMockServices {
 		Height:             testStartingHeight,
 		NodePubkey:         testNodePubkey,
 		Signature:          testSignature,
+		SignatureMsg:       testSignatureMsg,
 	}
 
 	lightningClient.lnd = &lnd
@@ -128,9 +130,10 @@ type LndMockServices struct {
 	RouterSendPaymentChannel chan RouterPaymentChannelMessage
 	TrackPaymentChannel      chan TrackPaymentMessage
 
-	Height     int32
-	NodePubkey string
-	Signature  []byte
+	Height       int32
+	NodePubkey   string
+	Signature    []byte
+	SignatureMsg string
 
 	WaitForFinished func()
 

test/signer_mock.go

@@ -1,6 +1,7 @@
 package test
 
 import (
+	"bytes"
 	"context"
 
 	"github.com/btcsuite/btcd/wire"
@@ -25,3 +26,14 @@ func (s *mockSigner) SignMessage(ctx context.Context, msg []byte,
 
 	return s.lnd.Signature, nil
 }
+
+func (s *mockSigner) VerifyMessage(ctx context.Context, msg, sig []byte,
+	pubkey [33]byte) (bool, error) {
+
+	// Make the mock somewhat functional by asserting that the message and
+	// signature is what we expect from the mock parameters.
+	mockAssertion := bytes.Equal(msg, []byte(s.lnd.SignatureMsg)) &&
+		bytes.Equal(sig, s.lnd.Signature)
+
+	return mockAssertion, nil
+}