From: Keith Busch <kbusch@kernel.org>
To: Chris Leech <cleech@redhat.com>
Cc: linux-nvme@lists.infradead.org, Hannes Reinecke <hare@suse.de>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
Chaitanya Kulkarni <kch@nvidia.com>,
Eric Biggers <ebiggers@kernel.org>
Subject: Re: [PATCH v2 REPOST] nvme-auth: Hash DH shared secret to create session key
Date: Wed, 22 Apr 2026 14:04:25 -0600 [thread overview]
Message-ID: <aekpyfAzqqIN6oKU@kbusch-mbp> (raw)
In-Reply-To: <20260422190636.2651992-1-cleech@redhat.com>
On Wed, Apr 22, 2026 at 12:06:36PM -0700, Chris Leech wrote:
> The NVMe Base Specification 8.3.5.5.9 states that the session key Ks
> shall be computed from the ephemeral DH key by applying the hash
> function selected by the HashID parameter.
>
> The current implementation stores the raw DH shared secret as the
> session key without hashing it. This causes redundant hash operations:
>
> 1. Augmented challenge computation (section 8.3.5.5.4) requires
> Ca = HMAC(H(g^xy mod p), C). The code compensates by hashing the
> unhashed session key in nvme_auth_augmented_challenge() to produce
> the correct result.
>
> 2. PSK generation (section 8.3.5.5.9) requires PSK = HMAC(Ks, C1 || C2)
> where Ks should already be H(g^xy mod p). As the DH shared secret
> is always larger than the HMAC block size, HMAC internally hashes
> it before use, accidentally producing the correct result.
Thanks, applied to nvme-7.1.
prev parent reply other threads:[~2026-04-22 20:04 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-22 19:06 [PATCH v2 REPOST] nvme-auth: Hash DH shared secret to create session key Chris Leech
2026-04-22 20:04 ` Keith Busch [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=aekpyfAzqqIN6oKU@kbusch-mbp \
--to=kbusch@kernel.org \
--cc=cleech@redhat.com \
--cc=ebiggers@kernel.org \
--cc=hare@suse.de \
--cc=hch@lst.de \
--cc=kch@nvidia.com \
--cc=linux-nvme@lists.infradead.org \
--cc=sagi@grimberg.me \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.