[PATCH] security: keys: switch big_key encryption to AES in CTR mode

[Eric Biggers]

[Added Jason Donenfeld to Cc]

Hi Ard,

On Fri, Sep 15, 2017 at 03:37:23PM -0700, Ard Biesheuvel wrote:
> The ECB chaining mode only supports inputs that are a multiple of the
> blocksize. Furthermore, it is not recommended for direct use, given
> that it may reveal recurring patterns in the plaintext, due to the
> lack of feedback between input blocks. So let's solve both issues at
> once, and switch to AES in CTR mode.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>

The choice of ECB here is definitely a mistake, but it really should use an
authenticated encryption mode such as GCM rather than plain CTR.  There was a
patch a few months ago that implemented this and fixed a couple other problems,
but it hasn't been merged; maybe someone wants to take over that patch instead?
Link: http://lkml.kernel.org/r/20170607101209.7603-1-Jason@zx2c4.com

Eric
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