Re: [PATCH v4] KEYS: encrypted: Instantiate key with user-provided decrypted data

[Jarkko Sakkinen <jarkko@kernel.org>]

On Wed, Jan 26, 2022 at 04:47:22PM +0200, Jarkko Sakkinen wrote:
> On Tue, Jan 18, 2022 at 01:26:05PM -0500, Martin Ross wrote:
> > Hi Jarkko,
> > 
> > I have been working with Yael on this project so I thought I might add
> > a bit of background here around the use case that this series of
> > patches is trying to address.
> > 
> > At a high level we are trying to provide users of encryption that have
> > key management hierarchies a better tradeoff between security and
> > availability.  For available and performance reasons master keys often
> > need to be released (or derived/wrapped keys created) outside of a KMS
> > to clients (which may in turn further wrap those keys in a series of
> > levels).  What we are trying to do is provide a mechanism where the
> > wrapping/unwrapping of these keys is not dependent on a remote call at
> > runtime.  e.g.  To unwrap a key if you are using AWS KMS or Google
> > Service you need to make an RPC.  In practice to defend against
> > availability or performance issues, designers end up building their
> > own kms and effectively encrypting everything with a DEK.  The DEK
> > encrypts same set as the master key thereby eliminating the security
> > benefit of keeping the master key segregated in the first place.

Mainly this part (would be enough to explain why it is there).

BR, Jarkko