Add encryption for SDK23+ (closes #7)

- delete unneeded drawables.xml
- fix custom host functionality

Author: Jared Tamana

android/ProtogenSSH/.idea/dictionaries/jared.xml

@@ -33,7 +33,7 @@ dependencies {
     implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
     implementation 'com.google.android.material:material:1.3.0-alpha01'
     implementation 'androidx.preference:preference:1.1.1'
-    //implementation 'androidx.security:security-crypto:1.0.0-rc02'
+    implementation 'androidx.security:security-crypto:1.0.0-rc02'
     // https://mvnrepository.com/artifact/com.jcraft/jsch
     implementation group: 'com.jcraft', name: 'jsch', version: '0.1.55'
 

android/ProtogenSSH/.idea/inspectionProfiles/Project_Default.xml

@@ -1,10 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
     package="com.jaredtamana.protogenssh">
 
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 
+    <uses-sdk tools:overrideLibrary="androidx.security"/>
+
     <application
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"

android/ProtogenSSH/app/build.gradle

@@ -5,6 +5,7 @@
 import android.app.Activity;
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.os.Build;
 import android.os.StrictMode;
 import android.view.View;
 import android.view.inputmethod.InputMethodManager;
@@ -13,6 +14,9 @@
 import android.widget.Toast;
 
 // Material imports
+import androidx.security.crypto.EncryptedSharedPreferences;
+import androidx.security.crypto.MasterKeys;
+
 import com.google.android.material.snackbar.BaseTransientBottomBar;
 import com.google.android.material.snackbar.Snackbar;
 
@@ -42,17 +46,47 @@ public class Functions {
     // (this does mean no responses can be grabbed by this function)
     // accepts string of command, context for sharedPrefs, view for snackbar
     // returns void
-    static public int executeSSHcommand(String command, Context context, View baseView) {
-        SharedPreferences sharedPreferences = context.getSharedPreferences("credentials", Context.MODE_PRIVATE); // open credentials file
-        String user = sharedPreferences.getString("username", "pi"); // use credentials unless not set, then use username pi
-        String password = sharedPreferences.getString("password", "raspberry"); // use credentials unless not set, then use password raspberry
-        String host = "192.168.4.1"; // use IP address, will end up adding a field for this later
-        int port = sharedPreferences.getInt("port", 22); // use credentials unless not set, then use port 22
+    static public void executeSSHcommand(String command, Context context, View baseView) {
+        int sdk = Build.VERSION.SDK_INT;
+        String user;
+        String password;
+        String host;
+        int port;
+        SharedPreferences sharedPreferences;
+        if (sdk >= 23){
+            String masterKeyAlias;
+            try {
+                masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC); // get master key
+                sharedPreferences = EncryptedSharedPreferences.create(
+                        "secret_shared_prefs",
+                        masterKeyAlias,
+                        context,
+                        EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+                        EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+                );
+            } catch (Exception e) {
+                e.printStackTrace();
+                Snackbar.make(baseView, "Failed to create encryption keys (IOException or SecurityException)", BaseTransientBottomBar.LENGTH_LONG)
+                        .show();
+                return;
+            }
+            user = sharedPreferences.getString(context.getString(R.string.username_sharedprop), "pi");
+            password = sharedPreferences.getString(context.getString(R.string.password_sharedprop), "raspberry");
+            host = sharedPreferences.getString(context.getString(R.string.host_sharedprop), "192.168.4.1");
+            port = sharedPreferences.getInt(context.getString(R.string.port_sharedprop), 22);
+        } else {
+            sharedPreferences = context.getSharedPreferences("credentials", Context.MODE_PRIVATE); // open credentials file
+            user = sharedPreferences.getString("username", "pi"); // use credentials unless not set, then use username pi
+            password = sharedPreferences.getString("password", "raspberry"); // use credentials unless not set, then use password raspberry
+            host = sharedPreferences.getString("host", "192.168.4.1"); // use IP address, will end up adding a field for this later
+            port = sharedPreferences.getInt("port", 22); // use credentials unless not set, then use port 22
+        }
         StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
                 .permitAll().build();
         StrictMode.setThreadPolicy(policy); // just a workaround
         try {
             JSch jsch = new JSch(); // instantiate a new JSch call
+            assert host != null;
             Session session = jsch.getSession(user, host, port); // set session credentials
             session.setPassword(password); // set password
             java.util.Properties config = new java.util.Properties();
@@ -70,15 +104,13 @@ static public int executeSSHcommand(String command, Context context, View baseVi
             Snackbar.make(baseView, R.string.connect_failed_snack, BaseTransientBottomBar.LENGTH_LONG)
                     .show(); // tell the user the command failed
         }
-        return 0;
     }
 
     // readFile function
     // Reads in button data and places buttons into the designated layout
     // accepts LinearLayout to be placed into, context for fileInput, view for snackbar
     // returns void
     public static void readFile(LinearLayout emoteListLayout, String fileName, final Context context, Activity activity, final View baseView) {
-        File internalStorageDir = context.getFilesDir();
         try {
             // instantiate fis
             FileInputStream fileInputStream = context.openFileInput(fileName);

android/ProtogenSSH/app/src/main/AndroidManifest.xml

@@ -1,11 +1,11 @@
 package com.jaredtamana.protogenssh.ui.settings;
 
-// imports for base Android
-
+// base imports
 import android.app.AlertDialog;
 import android.content.Context;
 import android.content.DialogInterface;
 import android.content.SharedPreferences;
+import android.os.Build;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -15,8 +15,8 @@
 // AndroidX imports
 import androidx.annotation.NonNull;
 import androidx.fragment.app.Fragment;
-//import androidx.security.crypto.EncryptedSharedPreferences;
-//import androidx.security.crypto.MasterKeys;
+import androidx.security.crypto.EncryptedSharedPreferences;
+import androidx.security.crypto.MasterKeys;
 
 // Material imports
 import com.google.android.material.snackbar.BaseTransientBottomBar;
@@ -27,6 +27,7 @@
 import com.jaredtamana.protogenssh.R;
 import com.jaredtamana.protogenssh.ui.Functions;
 
+
 public class SettingsFragment extends Fragment { // main fragment start
 
 
@@ -43,6 +44,7 @@ public View onCreateView(@NonNull LayoutInflater inflater,
         final TextInputEditText mInputPort = root.findViewById(R.id.inputPort);
         final TextInputEditText mInputUsername = root.findViewById(R.id.inputUsername);
         final TextInputEditText mInputPassword = root.findViewById(R.id.inputPassword);
+        final int sdk = Build.VERSION.SDK_INT;
         mFullFaceReset.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View view) { // when Reset Full Face Buttons button is clicked
@@ -149,13 +151,34 @@ public void onClick(View v) { // when save button is clicked
                         mInputHost.setError(getString(R.string.host_empty_error)); // set error flag on field
                         return; // stop before exception is thrown
                     }
-                    SharedPreferences credentialPrefs = getActivity().getSharedPreferences("credentials", Context.MODE_PRIVATE); // get credentials file
-                    SharedPreferences.Editor editor = credentialPrefs.edit(); // pull file into editor
-                    editor.putString(getString(R.string.host_sharedprop), mInputHost.getEditableText().toString()); // change host key to input
+
+                    SharedPreferences sharedPreferences;
+
+                    if (sdk >= 23) {
+                        String masterKeyAlias;
+                        try {
+                            masterKeyAlias = MasterKeys.getOrCreate(MasterKeys.AES256_GCM_SPEC);
+                            sharedPreferences = EncryptedSharedPreferences.create(
+                                    "secret_shared_prefs",
+                                    masterKeyAlias,
+                                    getContext(),
+                                    EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
+                                    EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
+                            );
+                        } catch (Exception e) {
+                            e.printStackTrace();
+                            Snackbar.make(getView(), "Failed to create encryption keys (IOException or SecurityException)", BaseTransientBottomBar.LENGTH_LONG)
+                                    .show();
+                            return;
+                        }
+                    } else {
+                        sharedPreferences = getActivity().getSharedPreferences("credentials", Context.MODE_PRIVATE); // get credentials file
+                    }
+
+                    SharedPreferences.Editor editor = sharedPreferences.edit();
+                    editor.putString(getString(R.string.host_sharedprop), mInputHost.getEditableText().toString());
                     editor.putInt(getString(R.string.port_sharedprop), Integer.parseInt(mInputPort.getEditableText().toString())); // change port key to input
                     editor.putString(getString(R.string.username_sharedprop), mInputUsername.getEditableText().toString()); // change username key to input
-                    // change password key to input
-                    // I want to implement encryption using androidx.security.crypto.EncryptedSharedPreferences but am having multiple issues, including the fact that sdk21 is needed
                     editor.putString(getString(R.string.password_sharedprop), mInputPassword.getEditableText().toString());
                     editor.apply(); // apply changes
                     Functions.hideKeyboard(getContext(), getView()); // hide the keyboard, it's no longer needed