Urbicide, cybercide and living memory

Is revision of history, so thorough that it is impossible to prove it, possible? The short answer, of course, is yes. In the past such revisions would take generations and coercion. In the future, as the bigger and bigger part of our lives relies on digitally stored information such revisions could be done in stealth and take less than a year. Reality is that we rely on our digital extensions for long-term memory. We are constantly bombarded with new data and in order to cope with the data flood we need to use digital extension of our memory.