add compressed flag for SignMessage

Author: rohenaz

examples/sign_message/sign_message.go

@@ -14,8 +14,11 @@ func main() {
 	}
 
 	// Sign the message (returning a signature)
+
+	// Note: If your signature references a compressed key,
+	// the address you provide to verify must also come from a compressed key
 	var signature string
-	if signature, err = bitcoin.SignMessage(privateKey, "This is the example message"); err != nil {
+	if signature, err = bitcoin.SignMessage(privateKey, "This is the example message", false); err != nil {
 		log.Fatalf("error occurred: %s", err.Error())
 	}
 

examples/verify_signature/verify_signature.go

@@ -19,6 +19,7 @@ func main() {
 	}
 
 	// Get an address from private key
+	// the compressed flag must match the flag provided during signing
 	var address string
 	address, err = bitcoin.GetAddressFromPrivateKey(rawKey, true)
 	if err != nil {

sign.go

@@ -11,9 +11,9 @@ import (
 )
 
 // SignMessage signs a string with the provided private key using Bitcoin Signed Message encoding
-//
+// sigRefCompressedKey bool determines whether the signature will reference a compressed or uncompresed key
 // Spec: https://docs.moneybutton.com/docs/bsv-message.html
-func SignMessage(privateKey string, message string) (string, error) {
+func SignMessage(privateKey string, message string, sigRefCompressedKey bool) (string, error) {
 	if len(privateKey) == 0 {
 		return "", errors.New("privateKey is empty")
 	}
@@ -38,7 +38,7 @@ func SignMessage(privateKey string, message string) (string, error) {
 
 	// Sign
 	var sigBytes []byte
-	if sigBytes, err = bsvec.SignCompact(bsvec.S256(), ecdsaPrivateKey, messageHash, false); err != nil {
+	if sigBytes, err = bsvec.SignCompact(bsvec.S256(), ecdsaPrivateKey, messageHash, sigRefCompressedKey); err != nil {
 		return "", err
 	}
 

sign_test.go

@@ -5,6 +5,43 @@ import (
 	"testing"
 )
 
+func TestSigningCompression(t *testing.T) {
+	testKey := "0499f8239bfe10eb0f5e53d543635a423c96529dd85fa4bad42049a0b435ebdd"
+	testData := "test message"
+
+	// Test sign uncompressed
+	address, err := GetAddressFromPrivateKeyString(testKey, false)
+	if err != nil {
+		t.Errorf("Get address err %s", err)
+	}
+	sig, err := SignMessage(testKey, testData, false)
+	if err != nil {
+		t.Errorf("Failed to sign uncompressed %s", err)
+	}
+
+	err = VerifyMessage(address, sig, testData)
+
+	if err != nil {
+		t.Errorf("Failed to validate uncompressed %s", err)
+	}
+
+	// Test sign compressed
+	address, err = GetAddressFromPrivateKeyString(testKey, true)
+	if err != nil {
+		t.Errorf("Get address err %s", err)
+	}
+	sig, err = SignMessage(testKey, testData, true)
+	if err != nil {
+		t.Errorf("Failed to sign compressed %s", err)
+	}
+
+	err = VerifyMessage(address, sig, testData)
+
+	if err != nil {
+		t.Errorf("Failed to validate compressed %s", err)
+	}
+}
+
 // TestSignMessage will test the method SignMessage()
 func TestSignMessage(t *testing.T) {
 
@@ -87,7 +124,7 @@ func TestSignMessage(t *testing.T) {
 
 	// Run tests
 	for idx, test := range tests {
-		if signature, err := SignMessage(test.inputKey, test.inputMessage); err != nil && !test.expectedError {
+		if signature, err := SignMessage(test.inputKey, test.inputMessage, false); err != nil && !test.expectedError {
 			t.Fatalf("%d %s Failed: [%s] [%s] inputted and error not expected but got: %s", idx, t.Name(), test.inputKey, test.inputMessage, err.Error())
 		} else if err == nil && test.expectedError {
 			t.Fatalf("%d %s Failed: [%s] [%s] inputted and error was expected", idx, t.Name(), test.inputKey, test.inputMessage)
@@ -99,7 +136,7 @@ func TestSignMessage(t *testing.T) {
 
 // ExampleSignMessage example using SignMessage()
 func ExampleSignMessage() {
-	signature, err := SignMessage("ef0b8bad0be285099534277fde328f8f19b3be9cadcd4c08e6ac0b5f863745ac", "This is a test message")
+	signature, err := SignMessage("ef0b8bad0be285099534277fde328f8f19b3be9cadcd4c08e6ac0b5f863745ac", "This is a test message", false)
 	if err != nil {
 		fmt.Printf("error occurred: %s", err.Error())
 		return
@@ -112,6 +149,6 @@ func ExampleSignMessage() {
 func BenchmarkSignMessage(b *testing.B) {
 	key, _ := CreatePrivateKeyString()
 	for i := 0; i < b.N; i++ {
-		_, _ = SignMessage(key, "This is a test message")
+		_, _ = SignMessage(key, "This is a test message", false)
 	}
 }

verify.go

@@ -41,7 +41,10 @@ func PubKeyFromSignature(sig, data string) (pubKey *bsvec.PublicKey, wasCompress
 }
 
 // VerifyMessage verifies a string and address against the provided
-// signature and assumes Bitcoin Signed Message encoding
+// signature and assumes Bitcoin Signed Message encoding.
+// The key referenced by the signature must relate to the address provided.
+// Do not provide an address from an uncompressed key along with
+// a signature from a compressed key
 //
 // Error will occur if verify fails or verification is not successful (no bool)
 // Spec: https://docs.moneybutton.com/docs/bsv-message.html