Re: CTS (cipher text stealing mode) and short packets

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Sep 29, 2008 at 6:18 PM, Russ Dill <russ.dill@xxxxxxxxx> wrote:
> crypto/cts.c currently implements RFC 3962. It deviates from the basic
> CTS algorithm in two ways. The first is that it does not support
> encrypting data blocks smaller than the underlying block size. Reading
> and writing past the end of buffers will occur if it is attempted.
>
> Second, when the length of data to be encrypted is exactly one block,
> it is encrypted with plain CBC.
>
> Normally, when packets are of size less than or equal to the block
> size, the algorithm uses the IV as the "previous block" and swaps bits
> with that data instead.
>
> What would be the best way to implement these slightly two different
> behaviors? The primary difference between the two CTS methods seems to
> be what to do when the input size is equal to the block size.

I'm not sure of the proper way to handle this.  My code depending on
this has not made it upstream yet, so I would not be opposed to
renaming this implementation to cts-rfc3962 (or any other conventional
name).  Assuming that noone else is already using this elsewhere.

Hopefully Herbert can give some experienced advice...

K.C.

p.s. I don't have a lot of time to devote to making changes myself right now...
--
To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Kernel]     [Gnu Classpath]     [Gnu Crypto]     [DM Crypt]     [Netfilter]     [Bugtraq]

  Powered by Linux