Migration to trusted keys: sealing user-provided key?

Jarkko Sakkinen jarkko at kernel.org
Sat Jan 30 17:53:39 UTC 2021

On Thu, 2021-01-28 at 18:31 +0100, Ahmad Fatoum wrote:
> Hello,
> I've been looking into how a migration to using trusted/encrypted keys
> would look like (particularly with dm-crypt).
> Currently, it seems the the only way is to re-encrypt the partitions
> because trusted/encrypted keys always generate their payloads from
> RNG.
> If instead there was a key command to initialize a new trusted/encrypted
> key with a user provided value, users could use whatever mechanism they
> used beforehand to get a plaintext key and use that to initialize a new
> trusted/encrypted key. From there on, the key will be like any other
> trusted/encrypted key and not be disclosed again to userspace.
> What are your thoughts on this? Would an API like
>   keyctl add trusted dmcrypt-key 'set <content>' # user-supplied content
> be acceptable?

Maybe it's the lack of knowledge with dm-crypt, but why this would be
useful? Just want to understand the bottleneck, that's all.

> Cheers,
> Ahmad


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