On 11/11/2023 8:36 pm, James Bottomley wrote: > On Sat, 2023-11-11 at 18:19 +0000, Andrew Cooper wrote: >> On 11/11/2023 5:44 pm, Eric Biggers wrote: >>> On Fri, Nov 10, 2023 at 05:27:44PM -0500, Ross Philipson wrote: >>>> arch/x86/boot/compressed/early_sha1.c | 12 ++++ >>>> lib/crypto/sha1.c | 81 >>>> +++++++++++++++++++++++++ >>> It's surprising to still see this new use of SHA-1 after so many >>> people objected to it in the v6 patchset. It's also frustrating >>> that the SHA-1 support is still being obfuscated by being combined >>> in one patch with SHA-2 support, perhaps in an attempt to conflate >>> the two algorithms and avoid having to give a rationale for the >>> inclusion of SHA-1. Finally, new functions should not be added to >>> lib/crypto/sha1.c unless those functions have multiple users. >> The rational was given. Let me reiterate it. >> >> There are real TPMs in the world that can't use SHA-2. The use of >> SHA-1 is necessary to support DRTM on such systems, and there are >> real users of such configurations. > Given that TPM 2.0 has been shipping in bulk since Windows 10 (2015) > and is required for Windows 11 (2021), are there really such huge > numbers of TPM 1.2 systems involved in security functions? Yes. As ever, it's not as simple as a straight TPM version issue. AMD's firmware-TPM2 isn't compatible with their DRTM implementation. Users are limited to whatever headers are available on the motherboard. Furthermore, even with a TPM2, it is the firmware (Intel TXT ACM) or hardware (AMD SKINIT) which chooses the hash algorithms to use, and in a lot of cases the end user doesn't get a choice. So yes - there really are modern systems which you can't use SHA-2-only with. >> DRTM with SHA-1-only is a damnsight better than no DTRM, even if SHA- >> 1 is getting a little long in the tooth. > That's not the problem. The problem is that sha1 is seen as a > compromised algorithm by NIST which began deprecating it in 2011 and is > now requiring it to be removed from all systems supplied to the US > government by 2030 This is a non-issue. People who care about having no SHA-1 can not compile in DRTM support. But there are people who will tolerate SHA-1 code to get DTRM support. ~Andrew
