On Thu, 1 Apr 2021 at 15:36, Ahmad Fatoum [off-list ref] wrote:

Hello Richard,

On 31.03.21 21:36, Richard Weinberger wrote:

quoted

James,

----- Ursprüngliche Mail -----

quoted

Von: "James Bottomley" [off-list ref]
Well, yes.  For the TPM, there's a defined ASN.1 format for the keys:

https://git.kernel.org/pub/scm/linux/kernel/git/jejb/openssl_tpm2_engine.git/tree/tpm2-asn.h

and part of the design of the file is that it's distinguishable either
in DER or PEM (by the guards) format so any crypto application can know
it's dealing with a TPM key simply by inspecting the file.  I think you
need the same thing for CAAM and any other format.

We're encouraging new ASN.1 formats to be of the form

SEQUENCE {
   type   OBJECT IDENTIFIER
   ... key specific fields ...
}

Where you choose a defined OID to represent the key and that means
every key even in DER form begins with a unique binary signature.

I like this idea.
Ahmad, what do you think?

That way we could also get rid off the kernel parameter and all the fall back logic,
given that we find a way to reliable detect TEE blobs too...

Sounds good to me. Sumit, your thoughts on doing this for TEE as well?

AFAIU, ASN.1 formating should be independent of trusted keys backends
which could be abstracted to trusted keys core layer so that every
backend could be plugged in seamlessly.

James,

Would it be possible to achieve this?

-Sumit

quoted

Thanks,
//richard

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