On Tue, May 09, 2023 at 06:21:44PM -0700, Eric Biggers wrote: > SHA-1 is insecure. Why are you still using SHA-1? Don't TPMs support SHA-2 > now? TXT is supported on some TPM 1.2 systems as well. TPM 2 systems are also at the whim of the firmware in terms of whether the SHA-2 banks are enabled. But even if the SHA-2 banks are enabled, if you suddenly stop extending the SHA-1 banks, a malicious actor can later turn up and extend whatever they want into them and present a SHA-1-only attestation. Ideally whatever is handling that attestation should know whether or not to expect an attestation with SHA-2, but the easiest way to maintain security is to always extend all banks.
