distinguishability and batching (was: Lurkers: First draft: call for comments (was: Paper deadlines))

[Zooko <zooko@zooko.com>]

 Roger wrote:
>
> i've added a bit more intuition about the need to make forwards and
> replies indistinguishable.

It now reads:

"By making forward messages and replies indistinguishable, we prevent an 
adversary from dividing the message anonymity sets into two classes.  In 
particular, if replies are infrequent relative to forward messages, an 
adversary who controls some of the MIXes can more easily trace the path of 
each reply: even though the batches may be large, the number of replies in 
each batch will be quite small."


I'm a bit dissatisfied with this because it seems to me that the best 
alternative to having indistinguishability is *not* the scary situation 
described in this quote, but instead batching the two classes of messages 
separately.  That may have its own drawbacks, but it doesn't seem nearly as 
bad as the "same batch, two classes" problem outlines above.

Regards,

Zooko

Zooko.Com -- Security and Distributed Systems Engineering