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

[Michael Walle]

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