Re: [PATCH 0/4] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys

[David Gstir]

Hi Ahmad,

> On 09.08.2021, at 12:16, Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> wrote:

[...]

> If it interests you, I described[2] my CAAM+ubifs+fscrypt use case in the
> discussion thread on my fscrypt-trusted-keys v1. Jan, a colleague of mine, held a
> talk[3] on the different solutions for authenticated and encrypted storage, which
> you may want to check out.
>
> I'd really appreciate feedback here on the the CAAM parts of this series, so this can
> eventually go mainline.

Since you mention the fscrypt trusted-keys use case:

I noticed that the key length for trusted-keys is limited to
256 - 1024bit keys. fscrypt does however also support keys
with e.g. 128bit keys (AES-128-CBC-ESSIV, AES-128-CTS-CBC).
AFAIK, CAAM and TEE key blobs would also support key lengths outside the 256 - 1024bit range.

Wouldn’t it make sense to align the supported key lengths?
I.e. extend the range of supported key lengths for trusted keys.
Or is there a specific reason why key lengths below 256bit are
not supported by trusted-keys?

Cheers,
David