linux-kernel - Re: [PATCH] lib/crypto: Add FIPS pre-operational self-test for SHA algorithms

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Message-ID: <87c17942-4c5b-45d6-b25d-089440b3d69b@jvdsn.com>
Date: Mon, 6 Oct 2025 22:42:44 -0500
From: Joachim Vandersmissen <git@...sn.com>
To: Eric Biggers <ebiggers@...nel.org>
Cc: linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
 Ard Biesheuvel <ardb@...nel.org>, "Jason A . Donenfeld" <Jason@...c4.com>,
 Vegard Nossum <vegard.nossum@...cle.com>, David Howells
 <dhowells@...hat.com>, Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] lib/crypto: Add FIPS pre-operational self-test for SHA
 algorithms

Hi Eric,

FIPS 140-3 always classifies Cryptographic Algorithm Self-Tests (CASTs) 
as conditional, even if they are executed on start-up. The condition 
would then be "start-up" or "initialization" or something similar. IG 
10.3.A explains it relatively well in the background section. For 
example, the Security Policy for 
https://csrc.nist.gov/projects/cryptographic-module-validation-program/certificate/5036 
shows the CASTs in Table 21.

In any case the name doesn't matter too much, even if you keep it the 
way it is, it wouldn't really impact a validation.

Kind regards,
Joachim

On 10/6/25 10:27 PM, Eric Biggers wrote:
> On Mon, Oct 06, 2025 at 10:03:44PM -0500, Joachim Vandersmissen wrote:
>> Hi Eric,
>>
>> It's a very minor change but I suggest not using "pre-operational
>> self-test". That term specifically refers to a different type of self-test
>> in FIPS 140-3 and it could lead to some confusion here. "cryptographic
>> algorithm self-test" may be better (if you want to be formal), or just
>> "self-test" or "known-answer test".
>>
> I don't think that's quite correct.  FIPS 140-3 divides self-tests into
> two categories, pre-operational (executed unconditionally at start-up
> time) and conditional (executed only when conditions are met, such as an
> algorithm being used for the first time).  This patch chooses the first
> option, pre-operational.
>
> We could just call them algorithm self-tests if we don't want to be
> specific as to what time they run at, though.
>
> - Eric
>