Spec. document

[George Danezis <gd@theory.lcs.mit.edu>]

Dear Friends,

I have been writing the outline of a spec. document about MixMinion (T3R) 
that I will be committing tomorrow evening, after I proof read it. You 
will be happy to know that it incorporates quite a few of the ideas that 
have been flowing around while it completely fails to address a lot of 
others: 

Included:
- The swap method + the header hashes are included.
- The fact that email addresses can be specified in the sub-header, and it 
  can span across many sub header blocks. To avoid the need for users to 
  run servers all the time.
- No more deadlines, only key rotation.
- A unified way of producing headers for forward + SURBs.

Not included:
- Mixing strategies (we need them if they require additional data in 
  headers) - Roger + David might want to have a go.
- Definition of formats for Mail, MixInfo, Statistics ...
  Zooko and Nick might be better at defining these than I am.
- No modules defined, no Nym Server protocols (separate documents IMHO)

Issues:
- The exact way one creates stateless reply blocks is not of a huge 
interest to the network as a whole. I am not sure we should be very 
restrictive. 
- I have set the hops for each header to be 16*128 bytes which makes a 
total of 4kb for the 2 headers. That leads us to a useful messages size of 
around 28kb. In order to minimize the size of reply blocks one could only 
provide the "useful" part of the SURB and a key (not secret) to generate 
the rest so that it matches the digests. (that could save some space)
(BTW is 16+16 hops and 32kb total size ok?)
- I am not sure how much we should specify the mixing strategy if it does 
not affect interoperability. Although it would be nice to know how much 
anonymity is extracted form each hop.
- A cool idea about publishing logs of messages seen: Mixes can use a hash 
tree to make both updating and querying about having seen messages 
efficient. 
- I have simplified the SSL based protocol to decrease the latency, Can be 
used as a fast pipe now! Check for attacks.

More details tomorrow, looking forward to hear your comments.

George