On Fri, May 12, 2023 at 03:24:04PM +0200, Thomas Gleixner wrote: > On Fri, May 12 2023 at 12:28, Matthew Garrett wrote: > > Unless we assert that SHA-1 events are unsupported, it seems a bit odd > > to force a policy on people who have both banks enabled. People with > > mixed fleets are potentially going to be dealing with SHA-1 measurements > > for a while yet, and while there's obviously a security benefit in using > > SHA-2 instead it'd be irritating to have to maintain two attestation > > policies. > > Why? > > If you have a mixed fleet then it's not too much asked to provide two > data sets. On a TPM2 system you can enforce SHA-2 and only fallback to > SHA-1 on TPM 1.2 hardware. No? No, beause having TPM2 hardware doesn't guarantee that your firmware enables SHA-2 (which also means this is something that could change with firmware updates, which means that refusing to support SHA-1 if the SHA-2 banks are enabled could result in an entirely different policy being required (and plausibly one that isn't implemented in their existing tooling)
