sqlcipher_export() and SQLiteOpenHelper conflict

[commonsguy]

Your test case for sqlcipher_export() uses SQLiteDatabase directly. However, when I try using it in conjunction with your SQLiteOpenHelper, I run into some issues. Specifically, the metadata that Android stores for version info does not seem to make it over to the encrypted database. As a result, when I turn around and try to use the encrypted database with SQLiteOpenHelper, Android tries upgrading the database from version 0 to 1, running through the SQLiteOpenHelper onCreate() logic again, which should not be necessary.

Here is the encrypt-my-unencrypted-database method that I am using:

static void encrypt(Context ctxt) throws IOException {
 SQLiteDatabase.loadLibs(ctxt);

 File dbFile=ctxt.getDatabasePath(DATABASE_NAME);
 File legacyFile=ctxt.getDatabasePath(LEGACY_DATABASE_NAME);

 if (!dbFile.exists() && legacyFile.exists()) {
  SQLiteDatabase db=
      SQLiteDatabase.openOrCreateDatabase(legacyFile, "", null);

  db.rawExecSQL(String.format("ATTACH DATABASE '%s' AS encrypted KEY '%s';",
                              dbFile.getAbsolutePath(), PASSPHRASE));
  db.rawExecSQL("SELECT sqlcipher_export('encrypted')");
  db.rawExecSQL("DETACH DATABASE encrypted;");
  db.close();
  legacyFile.delete();
 }
}

Thoughts?

Thanks!

[developernotes]

Hi Mark,

The user_version PRAGMA is explicitly excluded from the sqlcipher_export convenience function. There certain instances where migrating the current user_version is not preferable. The sqlcipher_export function does not require that the attached database be empty, thus you could legitimately have an existing user_version that you are migrating into and do not want to change.

In cases where you do want to carry over the user_version, you can do this manually by capturing the value with getVersion(), setting it after your migration with setVersion(...).

[commonsguy]

OK, that works. This, and the "is rawExecSQL() stable for long-term use", probably deserve a spot in the documentation, at some point.

Thanks!