On Fri, May 12 2023 at 17:13, Matthew Garrett wrote: > 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) It's not rocket science to have both variants supported in tooling, really. What a mess.
