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

Hi Ahmad,

On 09.08.2021, at 12:16, Ahmad Fatoum [off-list ref] 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