When segwit address is used to sign, we need to return the address signed with.

src/Features/Blockcore.Features.BlockStore/Models/SignMessageResult.cs

@@ -0,0 +1,16 @@
+using Newtonsoft.Json;
+
+namespace Blockcore.Features.BlockStore.Models
+{
+    /// <summary>
+    /// Class containing details of a signature message.
+    /// </summary>
+    public class SignMessageResult
+    {
+        [JsonProperty(PropertyName = "signedAddress")]
+        public string SignedAddress { get; set; }
+
+        [JsonProperty(PropertyName = "signature")]
+        public string Signature { get; set; }
+    }
+}

src/Features/Blockcore.Features.Wallet/Api/Controllers/WalletController.cs

@@ -7,6 +7,7 @@
 using System.Text;
 using Blockcore.Connection;
 using Blockcore.Connection.Broadcasting;
+using Blockcore.Features.BlockStore.Models;
 using Blockcore.Features.Wallet.Api.Models;
 using Blockcore.Features.Wallet.Exceptions;
 using Blockcore.Features.Wallet.Interfaces;
@@ -145,7 +146,7 @@ public IActionResult Create([FromBody]WalletCreationRequest request)
         /// Signs a message and returns the signature.
         /// </summary>
         /// <param name="request">The object containing the parameters used to sign a message.</param>
-        /// <returns>A JSON object containing the generated signature.</returns>
+        /// <returns>A JSON object containing the generated signature and the address used to sign.</returns>
         [Route("signmessage")]
         [HttpPost]
         public IActionResult SignMessage([FromBody]SignMessageRequest request)
@@ -160,7 +161,7 @@ public IActionResult SignMessage([FromBody]SignMessageRequest request)
 
             try
             {
-                string signature = this.walletManager.SignMessage(request.Password, request.WalletName, request.AccountName, request.ExternalAddress, request.Message);
+                SignMessageResult signature = this.walletManager.SignMessage(request.Password, request.WalletName, request.AccountName, request.ExternalAddress, request.Message);
                 return this.Json(signature);
             }
             catch (Exception e)

src/Features/Blockcore.Features.Wallet/Interfaces/IWalletManager.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using Blockcore.Features.BlockStore.Models;
 using Blockcore.Features.Wallet.Types;
 using NBitcoin;
 using NBitcoin.BuilderExtensions;
@@ -89,7 +90,7 @@ public interface IWalletManager
         /// <param name="externalAddress">Address to use to sign.</param>
         /// <param name="message">Message to sign.</param>
         /// <returns>The generated signature.</returns>
-        string SignMessage(string password, string walletName, string accountName, string externalAddress, string message);
+        SignMessageResult SignMessage(string password, string walletName, string accountName, string externalAddress, string message);
 
         /// <summary>
         /// Verifies the signed message.

src/Features/Blockcore.Features.Wallet/WalletManager.cs

@@ -9,6 +9,7 @@
 using Blockcore.Configuration;
 using Blockcore.Connection.Broadcasting;
 using Blockcore.EventBus;
+using Blockcore.Features.BlockStore.Models;
 using Blockcore.Features.Wallet.Exceptions;
 using Blockcore.Features.Wallet.Helpers;
 using Blockcore.Features.Wallet.Interfaces;
@@ -314,7 +315,7 @@ public Mnemonic CreateWallet(string password, string name, string passphrase, Mn
         }
 
         /// <inheritdoc />
-        public string SignMessage(string password, string walletName, string accountName, string externalAddress, string message)
+        public SignMessageResult SignMessage(string password, string walletName, string accountName, string externalAddress, string message)
         {
             Guard.NotEmpty(password, nameof(password));
             Guard.NotEmpty(walletName, nameof(walletName));
@@ -328,7 +329,11 @@ public string SignMessage(string password, string walletName, string accountName
             // Sign the message.
             HdAddress hdAddress = wallet.GetAddress(externalAddress, account => account.Name.Equals(accountName));
             Key privateKey = wallet.GetExtendedPrivateKeyForAddress(password, hdAddress).PrivateKey;
-            return privateKey.SignMessage(message);
+            return new SignMessageResult()
+            {
+                Signature = privateKey.SignMessage(message),
+                SignedAddress = hdAddress.Address
+            };
         }
 
         /// <inheritdoc />

src/Tests/Blockcore.IntegrationTests/Wallet/WalletOperationsTests.cs

@@ -5,6 +5,7 @@
 using System.Net;
 using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
+using Blockcore.Features.BlockStore.Models;
 using Blockcore.Features.Wallet;
 using Blockcore.Features.Wallet.Api.Models;
 using Blockcore.Features.Wallet.Types;
@@ -1493,7 +1494,7 @@ public async Task GetWalletFiles()
         public async Task SignMessage()
         {
             // Act.
-            string signatureResult = await $"http://localhost:{this.fixture.Node.ApiPort}/api"
+            SignMessageResult signatureResult = await $"http://localhost:{this.fixture.Node.ApiPort}/api"
                 .AppendPathSegment("wallet/signmessage")
                 .PostJsonAsync(new SignMessageRequest
                 {
@@ -1503,11 +1504,12 @@ public async Task SignMessage()
                     Password = this.fixture.walletWithFundsPassword,
                     Message = this.fixture.signatureMessage
                 })
-                .ReceiveJson<string>();
+                .ReceiveJson<SignMessageResult>();
 
             // Assert.
-            signatureResult.Should().Be(this.fixture.validSignature, $"Signature is invalid.");
-            Encoders.Base64.DecodeData(signatureResult).Should().BeOfType<byte[]>($"Signature was not a {typeof(byte[])} type.");
+            signatureResult.SignedAddress.Should().Be(this.fixture.addressWithFunds, $"Returned address is invalid.");
+            signatureResult.Signature.Should().Be(this.fixture.validSignature, $"Signature is invalid.");
+            Encoders.Base64.DecodeData(signatureResult.Signature).Should().BeOfType<byte[]>($"Signature was not a {typeof(byte[])} type.");
         }
 
         [Fact]