Merge pull request #4687

### pages/Sign.qml
@@ -58,9 +58,20 @@ Rectangle {
     }
 
     function displayVerificationResult(result) {
-        if (result) {
+        if (result.valid) {
             signatureVerificationMessage.title = qsTr("Good signature") + translationManager.emptyString
-            signatureVerificationMessage.text  = qsTr("This is a good signature") + translationManager.emptyString
+            if (result.type === "spend") {
+                signatureVerificationMessage.text = qsTr("This is a good signature made with the spend key.") + translationManager.emptyString
+            }
+            else if (result.type === "view") {
+                signatureVerificationMessage.text = qsTr("This is a good signature made with the view key. It does not prove that the signer can spend funds.") + translationManager.emptyString
+            }
+            else {
+                signatureVerificationMessage.text = qsTr("This is a good signature made with an unknown key type.") + translationManager.emptyString
+            }
+            if (result.old) {
+                signatureVerificationMessage.text += "\n\n" + qsTr("This signature uses the old signing algorithm.") + translationManager.emptyString
+            }
             signatureVerificationMessage.icon = StandardIcon.Information
         }
         else {
@@ -379,8 +390,8 @@ Rectangle {
                     text: qsTr("Verify File") + translationManager.emptyString
                     enabled: verifyFileLine.text !== '' && verifyAddressLine.text !== '' && verifySignatureLine.text !== ''
                     onClicked: {
-                      var verified = appWindow.currentWallet.verifySignedMessage(verifyFileLine.text, verifyAddressLine.text, verifySignatureLine.text, true)
-                      displayVerificationResult(verified)
+                      var result = appWindow.currentWallet.verifySignedMessageWithDetails(verifyFileLine.text, verifyAddressLine.text, verifySignatureLine.text, true)
+                      displayVerificationResult(result)
                     }
                 }
 
@@ -391,8 +402,8 @@ Rectangle {
                     text: qsTr("Verify Message") + translationManager.emptyString
                     enabled: verifyMessageLine.text !== '' && verifyAddressLine.text !== '' && verifySignatureLine.text !== ''
                     onClicked: {
-                      var verified = appWindow.currentWallet.verifySignedMessage(verifyMessageLine.text, verifyAddressLine.text, verifySignatureLine.text, false)
-                      displayVerificationResult(verified)
+                      var result = appWindow.currentWallet.verifySignedMessageWithDetails(verifyMessageLine.text, verifyAddressLine.text, verifySignatureLine.text, false)
+                      displayVerificationResult(result)
                     }
                 }
             }

### src/libwalletqt/Wallet.cpp
@@ -65,6 +65,23 @@ namespace {
     static const int WALLET_CONNECTION_STATUS_CACHE_TTL_SECONDS = 5;
 
     static constexpr char ATTRIBUTE_SUBADDRESS_ACCOUNT[] ="gui.subaddress_account";
+
+    QVariantMap messageSignatureResultToVariantMap(const Monero::Wallet::MessageSignatureResult &result)
+    {
+        QString type = "invalid";
+        switch (result.type) {
+        case Monero::Wallet::MessageSignatureType_Spend: type = "spend"; break;
+        case Monero::Wallet::MessageSignatureType_View: type = "view"; break;
+        default: break;
+        }
+
+        return {
+            {"valid", result.valid},
+            {"version", result.version},
+            {"old", result.old},
+            {"type", type}
+        };
+    }
 }
 
 Wallet::Wallet(QObject * parent)
@@ -1006,38 +1023,43 @@ QString Wallet::signMessage(const QString &message, bool filename) const
 }
 
 bool Wallet::verifySignedMessage(const QString &message, const QString &address, const QString &signature, bool filename) const
+{
+  return verifySignedMessageWithDetails(message, address, signature, filename).value("valid").toBool();
+}
+
+QVariantMap Wallet::verifySignedMessageWithDetails(const QString &message, const QString &address, const QString &signature, bool filename) const
 {
   if (filename) {
     QFile file(message);
     uchar *data = NULL;
 
     try {
       if (!file.open(QIODevice::ReadOnly))
-        return false;
+        return messageSignatureResultToVariantMap({});
       quint64 size = file.size();
       if (size == 0) {
         file.close();
-        return m_walletImpl->verifySignedMessage(std::string(), address.toStdString(), signature.toStdString());
+        return messageSignatureResultToVariantMap(m_walletImpl->verifySignedMessageWithDetails(std::string(), address.toStdString(), signature.toStdString()));
       }
       data = file.map(0, size);
       if (!data) {
         file.close();
-        return false;
+        return messageSignatureResultToVariantMap({});
       }
-      bool ret = m_walletImpl->verifySignedMessage(std::string(reinterpret_cast<const char*>(data), size), address.toStdString(), signature.toStdString());
+      const QVariantMap result = messageSignatureResultToVariantMap(m_walletImpl->verifySignedMessageWithDetails(std::string(reinterpret_cast<const char*>(data), size), address.toStdString(), signature.toStdString()));
       file.unmap(data);
       file.close();
-      return ret;
+      return result;
     }
     catch (const std::exception &e) {
       if (data)
         file.unmap(data);
       file.close();
-      return false;
+      return messageSignatureResultToVariantMap({});
     }
   }
   else {
-    return m_walletImpl->verifySignedMessage(message.toStdString(), address.toStdString(), signature.toStdString());
+    return messageSignatureResultToVariantMap(m_walletImpl->verifySignedMessageWithDetails(message.toStdString(), address.toStdString(), signature.toStdString()));
   }
 }
 bool Wallet::parse_uri(const QString &uri, QString &address, QString &payment_id, uint64_t &amount, QString &tx_description, QString &recipient_name, QVector<QString> &unknown_parameters, QString &error)

### src/libwalletqt/Wallet.h
@@ -36,6 +36,7 @@
 #include <QMutex>
 #include <QList>
 #include <QJSValue>
+#include <QVariantMap>
 #include <QtConcurrent/QtConcurrent>
 
 #include "wallet/api/wallet2_api.h" // we need to have an access to the Monero::Wallet::Status enum here;
@@ -322,6 +323,9 @@ class Wallet : public QObject, public PassprasePrompter
     //! verify a signed message
     Q_INVOKABLE bool verifySignedMessage(const QString &message, const QString &address, const QString &signature, bool filename = false) const;
 
+    //! verify a signed message and return the signature version and key type
+    Q_INVOKABLE QVariantMap verifySignedMessageWithDetails(const QString &message, const QString &address, const QString &signature, bool filename = false) const;
+
     //! Parse URI
     Q_INVOKABLE bool parse_uri(const QString &uri, QString &address, QString &payment_id, uint64_t &amount, QString &tx_description, QString &recipient_name, QVector<QString> &unknown_parameters, QString &error);
     //! Make URI