lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Thu, 30 Aug 2018 15:54:19 +0200
From:   Krzysztof Kozlowski <>
Subject: Re: Locking for HW crypto accelerators

On Thu, 30 Aug 2018 at 15:19, Stephan Mueller <> wrote:
> Am Donnerstag, 30. August 2018, 15:09:05 CEST schrieb Krzysztof Kozlowski:
> Hi Krzysztof,
> > Thanks Stephan for hints. Let's assume the each of init, update and
> > final are atomic... but how about the relation between update and
> > final? I have two concurrent users in user-space but only one HW:
> >
> > Process A:             Process B:
> > init() and set_key()
> >                        init() and different key
> > update(some_data)
> >                        update(different_data)
> > final()
> >                        final()
> >
> > The final() from process A will now produce the result of hashing/CRC
> > of some_data and different_data (and even maybe mixed with init() for
> > different key). All because in the meantime process B added its own
> > data to the HW.
> The question is where is the state of the cipher operation kept that is
> produced with each of the init/update/final calls. Your answer implies that
> this state is kept in hardware.

Yes, that's correct. The HW once initialized to specific CRC
parameters (size, polynomial, initial value), will operate on this
till another init happens.

> But commonly the state is kept in software. Look at ahash_request for example,
> the __ctx pointer is intended to point to the memory the driver needs to store
> its state.
> Pick a random driver implementation and search for ahash_request_ctx, for
> example.

I see now some drivers are indeed saving and restoring state.


Best regards,

Powered by blists - more mailing lists