From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 412B7EDEBF5 for ; Tue, 3 Mar 2026 22:48:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:In-Reply-To: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=pl2zG4pI79B5FV4b1qWY7o+8Dm13AOeYPsXsZmBVTMc=; b=41so4Yw40DPPZ79HDaumcWx4Id cJY2Kq235WbcKipAx9+ivOqzWC1c5yNnFTnM6RRgYpqBXjGCQUYAStYuKQOfFzrrbwaQ/z6ccQCEo V80XfNh53Mm01v65jq5D025gQWtubHsDQpFl/FpAgVhjXGMGCIY+Aup47adDFs1GF2oSlZPXYI035 CGywD2TG64R4EYz/mxDN79uJnMbsf8yAlAxWLj5nct94gHcYjS9Fsy8sUGqXQY3v8FMGATJAmDIYP PGXYcTNwsQbwzOk68XUGFqasRkLnK1+5HPANRQhxhcRb5PGrCquuV6DieVg6XiqKhwV8sPpDMNH0h isvsb03A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxYXD-0000000G3X0-3qgC; Tue, 03 Mar 2026 22:48:11 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vxYXB-0000000G3Wa-2yAb for linux-nvme@lists.infradead.org; Tue, 03 Mar 2026 22:48:10 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1772578088; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=pl2zG4pI79B5FV4b1qWY7o+8Dm13AOeYPsXsZmBVTMc=; b=H7TVK/8GBTk7a8u2gaW3JKgA/BI45wxvXs7BUvpT0IKNVxHAFyd4kWhZ5EqcLxaenKlwRZ 1wvjjzLVnOYW81wPATtkSzJes9vQzZ52j5MaKj05RUlizsZCh7ymJi1y6gShQ4cA7JFl1Y mV0uj7elj30Iiu3YSsZqyV4YcEPfW8Y= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-130-RgNbitvyOf-TNuzEwPefWA-1; Tue, 03 Mar 2026 17:48:04 -0500 X-MC-Unique: RgNbitvyOf-TNuzEwPefWA-1 X-Mimecast-MFC-AGG-ID: RgNbitvyOf-TNuzEwPefWA_1772578082 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 48965180034D; Tue, 3 Mar 2026 22:48:01 +0000 (UTC) Received: from my-developer-toolbox-latest (unknown [10.2.16.250]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 9194718005A7; Tue, 3 Mar 2026 22:47:57 +0000 (UTC) Date: Tue, 3 Mar 2026 14:47:56 -0800 From: Chris Leech To: Eric Biggers Cc: Hannes Reinecke , linux-nvme@lists.infradead.org, Chaitanya Kulkarni , Sagi Grimberg , Christoph Hellwig , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, Ard Biesheuvel , "Jason A . Donenfeld" , Herbert Xu Subject: Re: [PATCH 04/21] nvme-auth: common: add KUnit tests for TLS key derivation Message-ID: <20260303-slush-hydrated-8b1929ec6a30@redhat.com> References: <20260302075959.338638-1-ebiggers@kernel.org> <20260302075959.338638-5-ebiggers@kernel.org> <1de7ef59-4236-4372-81f6-60d5a4f1e253@suse.de> <20260303002649.GE20209@quark> MIME-Version: 1.0 In-Reply-To: <20260303002649.GE20209@quark> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 X-Mimecast-MFC-PROC-ID: 0J9RIjIGHNGoah6gj2ERqnE6d76IL5mRPRjUaRi7Lo8_1772578082 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260303_144809_823972_6D620D66 X-CRM114-Status: GOOD ( 17.67 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Mon, Mar 02, 2026 at 04:26:49PM -0800, Eric Biggers wrote: > On Mon, Mar 02, 2026 at 11:04:43AM +0100, Hannes Reinecke wrote: > > Which discrepancies do you see between the specified algorithm > > and the implementation? > > I'm looking at the latest NVM Express Base Specification, v2.3. > > First, there's the following: > > The host computes KS as the hash of the ephemeral DH key resulting > from the combination of the random value y selected by the host with > the DH exponential (i.e., gx mod p) received from the controller > (i.e., KS = H((gx mod p)y mod p) = H(gxy mod p)). > > The actual code skips that step when deriving the PSK, and just > considers the DH value directly to be "KS" and uses it directly as an > HMAC key. That is something that should never be done. DH values are > not uniformly distributed and must not be used directly as keys. I'm doing some testing with a patch to immediatly hash the DH value after the kpp request is complete, fixing nvme_auth_generate_psk(), while removing the hashing step from nvme_auth_augmented_challenge(). That only allows the use of KS as the raw DH output is not saved. But, I think things are saved by DH values always being larger than the HMAC block size and therefor hashed within hmac_shaXXX_preparekey(). Maybe more lucky than correct, but the same result. - Chris