On Wed, Jul 31, 2019 at 3:29 PM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > > For WAL encryption, before flushing WAL we encrypt whole 8k WAL page > and then write only the encrypted data of the new WAL record using > pg_pwrite() rather than write whole encrypted page. So each time we > encrypt 8k WAL page we end up with encrypting different data with the > same key+nonce but since we don't write to the disk other than space > where we actually wrote WAL records it's not a problem. Is that right?
Hmm that's incorrect. We always write an entire 8k WAL page even if we write a few WAl records into a page. It's bad because we encrypt different pages with the same key+IV, but we cannot change IV for each WAL writes as we end up with changing also already-flushed-WAL-records. So we might need to change the WAL write so that it write only WAL records we actually wrote. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
