Runtime update of Room database password

SQLCipher
1

Since Room does not provide official support for encryption I decided to ask here.

I am trying to update database password of already encrypted database. I manage to do it with suggested PRAGMA rekey="newKey", meaning when I pull the database files from the device and use SQLCipher for Windows, I can read it with newKey. Problem happens when I inject the Room database in my repository, that instance probably tries to read the database with old password and I get the file is not a database exception.
It seems to me like underlying SQLite database is encrypted with new key, but Room is not aware of it and uses oldKey which was set through SupportOpenHelperFactory. So my current pseudo code which works is this:

fun buildDB(): RoomDB {
  //set builder with old pass
  val builder = Room.databaseBuilder(...).openHelperFactory(SupportOpenHelperFactory("oldKey".toByteArray())).
  var db = builder.build()
  // change db pass
  db.openHelper.writableDatabase.query("PRAGMA rekey = 'newKey';")
  
  // here I still have open connection with newKey so I could do any kind of queries and it works
  // for example 
  // db.openHelper.writableDatabase.query("SELECT COUNT(*) FROM sqlite_schema;")
  
  // close the connection
  db.close()
  // create new builder with new pass
  val builder2 = Room.databaseBuilder(...).openHelperFactory(SupportOpenHelperFactory("newKey".toByteArray())).
  db = builder2.build()

  return db
}

then this db instance is returned to my @Provides and @Singleton annotated method in my Dagger module.
So my questions are

  • Why does it work in the buildDB function but once that instance is injected into my repository for example, I can not query it? It is same instance but it seems like Room closed the connection and tried to open it with old password.
  • Is there a better way to achieve this, without the need to recreate RoomDatabase instance? Is there a way to update the password on already created instance?
  • Why is there no changePassword function in SupportSQLiteDatabase like it was in SQLiteDatabase?