CFB Mode

[Michael Halcrow]

On Mon, Aug 30, 2004 at 12:41:41PM -0500, Michael Halcrow wrote:
> On Mon, Aug 30, 2004 at 02:36:27PM -0400, James Morris wrote:
> > On Mon, 30 Aug 2004, Michael Halcrow wrote:
> > 
> > > recommended approach to dealing with this, or can I go ahead and make
> > > some invasive changes that will process data sizes that are not even
> > > multiple of the block size, given certain cipher modes?
> > 
> > What do other crypto APIs do in this case?  (e.g. Nettle, Gnu
> > Crypto, OpenSSL etc).
> 
> I'll take a look at those as soon as I finish with my changes to the
> kernel crypto API.  I've narrowed down the changes to these (so far -
> don't apply, this is just some playing around for now):
> 

Okay, scratch all that about the size and what not.  There is nothing
wrong with just passing in garbage for the remainder of the plaintext;
with CFB, the user can just ignore the corresponding ciphertext.  In
order to replicate RFC 2440's CFB, I will have to start out the
process manually with ECB, and then pass the ``primed'' IV into the
cipher in CFB mode.

Mike
.___________________________________________________________________.
                         Michael A. Halcrow                          
       Security Software Engineer, IBM Linux Technology Center       
GnuPG Fingerprint: 05B5 08A8 713A 64C1 D35D  2371 2D3C FDDA 3EB6 601D
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