On Wed, May 26, 2021 at 05:11:24PM -0700, Andres Freund wrote: > Hi, > > On 2021-05-25 17:12:05 -0400, Bruce Momjian wrote: > > If we used a block cipher instead of a streaming one (CTR), this might > > not work because the earlier blocks can be based in the output of > > later blocks. > > What made us choose CTR for WAL & data file encryption? I checked the > README in the patchset and the wiki page, and neither seem to discuss > that. > > The dangers around nonce reuse, the space overhead of storing the nonce, > the fact that single bit changes in the encrypted data don't propagate > seem not great? Why aren't we using something like XTS? It has obvious > issues as wel, but CTR's weaknesses seem at least as great. And if we > want a MAC, then we don't want CTR either.
We chose CTR because it was fast, and we could use the same method for WAL, which needs a streaming, not block, cipher. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com If only the physical world exists, free will is an illusion.
