Hi, On 12.08.21 02:54, Mimi Zohar wrote: > On Wed, 2021-08-11 at 10:16 -0700, Eric Biggers wrote: > >> Neither of you actually answered my question, which is whether the support for >> trusted keys in dm-crypt is a mistake. I think you're saying that it is? That >> would imply that fscrypt shouldn't support trusted keys, but rather encrypted >> keys -- which conflicts with Ahmad's patch which is adding support for trusted >> keys. Note that your reasoning for this is not documented at all in the >> trusted-encrypted keys documentation; it needs to be (email threads don't really >> matter), otherwise how would anyone know when/how to use this feature? > > True, but all of the trusted-encrypted key examples in the > documentation are "encrypted" type keys, encrypted/decrypted based on a > "trusted" type key. There are no examples of using the "trusted" key > type directly. Before claiming that adding "trusted" key support in > dm-crypt was a mistake, we should ask Ahmad why he felt dm-crypt needed > to directly support "trusted" type keys. I wanted to persist the dm-crypt key as a sealed blob. With encrypted keys, I would have to persist and unseal two blobs (load trusted key blob, load encrypted key blob rooted to trusted key) with no extra benefit. I thus added direct support for trusted keys. Jarkko even commented on the thread, but didn't voice objection to the approach (or agreement for that matter), so I assumed the approach is fine. I can see the utility of using a single trusted key for TPMs, but for CAAM, I see none and having an encrypted key for every trusted key just makes it more cumbersome. In v1 here, I added encrypted key support as well, but dropped it for v2, because I am not in a position to justify its use. Now that you and Eric discussed it, should I send v3 with support for both encrypted and trusted keys like with dm-crypt or how should we proceed? Cheers, Ahmad > > Mimi > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
