Ross Anderson told MPs that the upcoming release of Windows Vista would mean more computer files being encrypted.
He urged the government to look at establishing "back door" ways of getting around encryptions.
The Home Office later told the BBC News website it is in talks with Microsoft.
Did I just miss the last ten years, or did you speak too soon?
UPDATE: See my other post on this thread for another perspective from Peter Gutmann.
Ross Anderson urges Parliament to mandate key escrow; Microsoft agrees