Show PGP signature status

app/src/main/java/eu/faircode/email/ActivityView.java

@@ -74,6 +74,7 @@ import com.google.android.material.snackbar.Snackbar;
 import org.json.JSONArray;
 import org.json.JSONObject;
 import org.openintents.openpgp.OpenPgpError;
+import org.openintents.openpgp.OpenPgpSignatureResult;
 import org.openintents.openpgp.util.OpenPgpApi;
 import org.openintents.openpgp.util.OpenPgpServiceConnection;
 
@@ -100,6 +101,9 @@ import javax.mail.Session;
 import javax.mail.internet.MimeMessage;
 import javax.net.ssl.HttpsURLConnection;
 
+import static org.openintents.openpgp.OpenPgpSignatureResult.RESULT_NO_SIGNATURE;
+import static org.openintents.openpgp.OpenPgpSignatureResult.RESULT_VALID_KEY_CONFIRMED;
+
 public class ActivityView extends ActivityBilling implements FragmentManager.OnBackStackChangedListener {
     private String startup;
 
@@ -1445,6 +1449,18 @@ public class ActivityView extends ActivityBilling implements FragmentManager.OnB
                             }
                         }
 
+                        // Check signature status
+                        OpenPgpSignatureResult sigResult = result.getParcelableExtra(OpenPgpApi.RESULT_SIGNATURE);
+                        int sresult = (sigResult == null ? RESULT_NO_SIGNATURE : sigResult.getResult());
+                        int resid;
+                        if (sresult == RESULT_NO_SIGNATURE)
+                            resid = R.string.title_signature_none;
+                        else if (sresult == RESULT_VALID_KEY_CONFIRMED)
+                            resid = R.string.title_signature_valid;
+                        else
+                            resid = R.string.title_signature_invalid;
+                        Snackbar.make(getVisibleView(), resid, Snackbar.LENGTH_LONG).show();
+
                         break;
 
                     case OpenPgpApi.RESULT_CODE_USER_INTERACTION_REQUIRED:

app/src/main/res/values/strings.xml

@@ -500,6 +500,10 @@
     <string name="title_no_openpgp">OpenKeychain not found</string>
     <string name="title_not_encrypted">Message is not encrypted</string>
 
+    <string name="title_signature_none">Message not signed</string>
+    <string name="title_signature_valid">Message signature valid</string>
+    <string name="title_signature_invalid">Message signature invalid</string>
+
     <string name="title_search">Search</string>
     <string name="title_search_in">Search in</string>
     <string name="title_searching">Searching \'%1$s\'</string>