On Fri, 15 May 2020 at 04:40, Tzung-Bi Shih <tzungbi@xxxxxxxxxx> wrote: > > On Fri, May 15, 2020 at 12:26 AM Benson Leung <bleung@xxxxxxxxxx> wrote: > > On Thu, May 14, 2020 at 06:18:47PM +0200, Ard Biesheuvel wrote: > > > The CrOS EC codec driver uses SHA-256 explicitly, and not in a > > > performance critical manner, so there is really no point in using > > > the dynamic SHASH crypto API here. Let's switch to the library API > > > instead. > > Pardon me if I don't understand it precisely. What is the difference > between the two APIs? Suppose it should calculate the same SHA256 > hash with the same binary blob after switching to library API? > Yes. > > > Looking at the code, I was wondering if the SHA-256 is really required > > > here? It looks like it is using it as some kind of fingerprint to decide > > > whether the provided file is identical to the one that has already been > > > loaded. If this is the case, we should probably just use CRC32 instead. > > No, the binary blob carries data and possibly code. We are not only > using the hash as a fingerprint but also an integrity check. > But does it have to be cryptographically strong? Why is CRC32 not sufficient? > > > Also, do we really need to wipe the context struct? Is there any security > > > sensitive data in there? > > No, not necessary as far as I know. OK
