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From: Mimi Zohar <firstname.lastname@example.org> To: Ahmad Fatoum <email@example.com>, Eric Biggers <firstname.lastname@example.org>, Jarkko Sakkinen <email@example.com> Cc: "Theodore Y. Ts'o" <firstname.lastname@example.org>, Jaegeuk Kim <email@example.com>, firstname.lastname@example.org, James Morris <email@example.com>, "Serge E. Hallyn" <firstname.lastname@example.org>, James Bottomley <email@example.com>, Sumit Garg <firstname.lastname@example.org>, David Howells <email@example.com>, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com Subject: Re: [PATCH v2] fscrypt: support trusted keys Date: Tue, 17 Aug 2021 09:55:13 -0400 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> On Tue, 2021-08-17 at 15:04 +0200, Ahmad Fatoum wrote: > 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? With some applications, the indirection is important. It allows the "encrypted" key type to be updated/re-encypted based on a new "trusted" key, without affecting the on disk encrypted key usage. As much as I expected, directly using "trusted" keys is a result of the new trusted key sources. I have no opinion as to whether this is/isn't a valid usecase. thanks, Mimi
next prev parent reply other threads:[~2021-08-17 13:55 UTC|newest] Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-08-06 15:09 [PATCH v2] fscrypt: support trusted keys Ahmad Fatoum 2021-08-09 9:44 ` Jarkko Sakkinen 2021-08-09 10:00 ` Ahmad Fatoum 2021-08-09 10:02 ` Ahmad Fatoum 2021-08-10 18:02 ` Jarkko Sakkinen 2021-08-09 20:52 ` Eric Biggers 2021-08-10 18:06 ` Jarkko Sakkinen 2021-08-10 18:46 ` Eric Biggers 2021-08-10 21:21 ` Jarkko Sakkinen 2021-08-10 21:27 ` Eric Biggers 2021-08-11 0:17 ` Jarkko Sakkinen 2021-08-11 11:34 ` Mimi Zohar 2021-08-11 17:16 ` Eric Biggers 2021-08-12 0:54 ` Mimi Zohar 2021-08-17 13:04 ` Ahmad Fatoum 2021-08-17 13:55 ` Mimi Zohar [this message] 2021-08-17 14:13 ` Ahmad Fatoum 2021-08-17 14:24 ` Mimi Zohar 2021-08-18 2:09 ` Jarkko Sakkinen 2021-08-18 4:53 ` Sumit Garg 2021-08-09 21:24 ` Eric Biggers 2021-08-10 7:41 ` Ahmad Fatoum 2021-08-10 17:35 ` Eric Biggers
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