Re: [RFC PATCH HBK: 0/8] HW BOUND KEY as TRUSTED KEY

From: Michael Walle <michael@walle.cc>
To: Pankaj Gupta <pankaj.gupta@nxp.com>
Cc: jarkko@kernel.org, a.fatoum@pengutronix.de, Jason@zx2c4.com,
	jejb@linux.ibm.com, zohar@linux.ibm.com, dhowells@redhat.com,
	sumit.garg@linaro.org, david@sigma-star.at,
	john.ernberg@actia.se, jmorris@namei.org, serge@hallyn.com,
	herbert@gondor.apana.org.au, davem@davemloft.net,
	j.luebbe@pengutronix.de, ebiggers@kernel.org, richard@nod.at,
	keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
	linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org, sahil.malhotra@nxp.com,
	kshitiz.varshney@nxp.com, horia.geanta@nxp.com, V.Sethi@nxp.com
Subject: Re: [RFC PATCH HBK: 0/8] HW BOUND KEY as TRUSTED KEY
Date: Tue, 06 Sep 2022 09:12:33 +0200	[thread overview]
Message-ID: <047746e1134d5bdce699d8c021f849b6@walle.cc> (raw)
In-Reply-To: <20220906065157.10662-1-pankaj.gupta@nxp.com>

Hi,

Am 2022-09-06 08:51, schrieb Pankaj Gupta:
> Hardware Bound key(HBK), is never acessible as plain key outside of the
> hardware boundary. Thus, it is un-usable, even if somehow fetched
> from kernel memory. It ensures run-time security.
> 
> This patchset adds generic support for classing the Hardware Bound Key,
> based on:
> 
> - Newly added flag-'is_hbk', added to the tfm.
> 
>   Consumer of the kernel crypto api, after allocating
>   the transformation, sets this flag based on the basis
>   of the type of key consumer has.
> 
> - This helps to influence the core processing logic
>   for the encapsulated algorithm.
> 
> - This flag is set by the consumer after allocating
>   the tfm and before calling the function crypto_xxx_setkey().
> 
> First implementation is based on CAAM.
> 
> NXP built CAAM IP is the Cryptographic Acceleration and Assurance 
> Module.
> This is contain by the i.MX and QorIQ SoCs by NXP.
> 
> CAAM is a suitable backend (source) for kernel trusted keys.
> This backend source can be used for run-time security as well
> by generating the hardware bound key.
> 
> Along with plain key, the CAAM generates black key. A black key is an
> encrypted key, which can only be decrypted inside CAAM. Hence, CAAM's
> black key can only be used by CAAM. Thus it is declared as a hardware 
> bound key.

What is the difference to the current trusted keys with CAAM?
When I tested the patch series back then, I wasn't able to import
a sealed key on another board with the same SoC.

-michael