CWAC-SafeRoom: A Room<->SQLCipher for Android Bridge

This project implements the Support... series of classes and interfaces that Room can use for working with a particular edition of SQLite. Specficially, this project's classes connect Room with SQLCipher for Android, a version of SQLite that offers transparent encryption of its contents.

Right now, this project is for experimentation purposes and for helping to prove the practicality of the Support... class setup. Do not use this in production applications just yet.

This Android library project is available as a JAR or as an artifact for use with Gradle. To use that, add the following blocks to your build.gradle file:

repositories {
    maven {
        url "https://s3.amazonaws.com/repo.commonsware.com"
    }
}

dependencies {
    compile 'com.commonsware.cwac:saferoom:0.0.3'
}

Or, if you cannot use SSL, use http://repo.commonsware.com for the repository URL.

Usage

When you use Room, you use Room.databaseBuilder() or Room.inMemoryDatabaseBuilder() to get a RoomDatabase.Builder. After configuring that object, you call build() to get an instance of your custom subclass of RoomDatabase, whichever one that you supplied as a Java class object to the Room.databaseBuilder() or Room.inMemoryDatabaseBuilder() method.

To use SafeRoom, on the RoomDatabase.Builder, before calling build():

Create an instance of com.commonsware.cwac.saferoom.SafeHelperFactory, passing in the passphrase to use
Pass that SafeHelperFactory to the RoomDatabase.Builder via the openHelperFactory() method

// EditText passphraseField;
SafeHelperFactory factory=SafeHelperFactory.fromUser(passphraseField.getText());

StuffDatabase db=Room.databaseBuilder(ctxt, StuffDatabase.class, DB_NAME)
  .openHelperFactory(factory)
  .build();

Passphrase Management

A cardinal rule of passphrases in Java is: do not hold them in String objects. You have no means of clearing those from memory, as a String is an immutable value.

The SafeHelperFactory constructor takes a char[] for the passphrase. If you are getting the passphrase from the user via an EditText widget, use the fromUser() factory method instead, supplying the Editable that you get from getText() on the EditText.

SafeRoom will zero out the char[] once the database is opened. If you use fromUser(), SafeRoom will also clear the contents of the Editable.

Dependencies

As one might expect, this project depends on SQLCipher for Android.

This project also depends on the Room runtime artifact. Eventually, that will be downgraded to only depending on the support-db artifact, once we no longer need to use reflection with RoomSQLiteQuery to get the argument count.

Version

This is version v0.0.3 of this module, meaning it still has that new-code smell.

Demo

Right now, there is no demo project, though you can putter around the instrumentation tests.

Additional Documentation

JavaDocs are available, though most of the library is not public, as it does not need to be.

Android's Architecture Components contains a chapter dedicated to SafeRoom.

License

The code in this project is licensed under the Apache Software License 2.0, per the terms of the included LICENSE file.

Questions

If you have questions regarding the use of this code, please post a question on Stack Overflow tagged with commonsware-cwac and android after searching to see if there already is an answer. Be sure to indicate what CWAC module you are having issues with, and be sure to include source code and stack traces if you are encountering crashes.

If you have encountered what is clearly a bug, or if you have a feature request, please post an issue. Be certain to include complete steps for reproducing the issue. The contribution guidelines provide some suggestions for how to create a bug report that will get the problem fixed the fastest.

You are also welcome to join the CommonsWare Community and post questions and ideas to the CWAC category.

Do not ask for help via social media.

Also, if you plan on hacking on the code with an eye for contributing something back, please open an issue that we can use for discussing implementation details. Just lobbing a pull request over the fence may work, but it may not. Again, the contribution guidelines provide a bit of guidance here.

Release Notes

v0.0.3: raised Room dependencies to 1.0.0-alpha8
v0.0.2: raised Room dependencies to 1.0.0-alpha5
v0.0.1: initial release

cloudbank / cwac-saferoom