[PATCH 1/2] crypto: hkdf: add hkdf_expand_label()

[Hannes Reinecke]

On 8/20/25 21:48, Chris Leech wrote:
> On Wed, Aug 20, 2025 at 11:46:33AM -0700, Eric Biggers wrote:
>> On Wed, Aug 20, 2025 at 11:12:10AM +0200, hare at kernel.org wrote:
>>> From: Chris Leech <cleech at redhat.com>
>>>
>>> Provide an implementation of RFC 8446 (TLS 1.3) HKDF-Expand-Label
>>>
>>> Cc: Eric Biggers <ebiggers at kernel.org>
>>> Signed-off-by: Chris Leech <cleech at redhat.com>
>>> Signed-off-by: Hannes Reinecke <hare at kernel.org>
>>> ---
>>>   crypto/hkdf.c         | 55 +++++++++++++++++++++++++++++++++++++++++++
>>>   include/crypto/hkdf.h |  4 ++++
>>>   2 files changed, 59 insertions(+)
>>>
>>> ...
>>
>> Does this belong in crypto/hkdf.c?  It seems to be specific to a
>> particular user of HKDF.
> 
> While this is needed for NVMe/TLS, it's a case of the NVMe
> specifications referencing a function defined in the TLS 1.3 RFC to be
> used.  I though it would be clearest to fix the open-coded implemenation
> by creating an RFC complient function, which is now no-longer specific
> to NVMe so I moved it out to crypto/hkdf.c
> 
> I don't know that there will be other users, it just seemed to make the
> most sense there.
> 
But having said that, we can easily move it into the nvme code, and let
others move it into crypto if there is a need.
Will be updating the patchset.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare at suse.de                                +49 911 74053 688
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