%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%deffont "standard" xfont "comic sans ms-medium-r"
%%deffont "thick" xfont "arial black-medium-r"
%%deffont "typewriter" xfont "courier new-bold-r"
%%deffont "type2writer" xfont "arial narrow-bold-r"
%%deffont "standard"   tfont "standard.ttf",   tmfont "kochi-mincho.ttf"
%%deffont "thick"      tfont "thick.ttf",      tmfont "goth.ttf"
%%deffont "typewriter" tfont "typewriter.ttf", tmfont "goth.ttf"
%deffont "standard" xfont "helvetica-medium-r", tfont "arial.ttf", tmfont "times.ttf"
%deffont "thick" xfont "helvetica-bold-r", tfont "arialbd.ttf", tmfont "hoso6.ttf"
%deffont "italic" xfont "helvetica-italic-r", tfont "ariali.ttf", tmfont "hoso6.ttf"
%deffont "typewriter" xfont "courier-medium-r", tfont "typewriter.ttf", tmfont "hoso6.ttf"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Default settings per each line numbers.
%%
%default 1 leftfill, size 8, fore "black", back "white", font "thick", hgap 1
%default 2 size 8, vgap 10, prefix " ", ccolor "black"
%default 3 size 6, bar "gray70", vgap 0
%default 4 size 6, fore "black", vgap 0, prefix " ", font "standard"
%%
%%default 1 area 90 90, leftfill, size 9, fore "yellow", back "blue", font "thick"
%%default 2 size 9, vgap 10, prefix " "
%%default 3 size 7, bar "gray70", vgap 10
%%default 4 size 7, vgap 30, prefix " ", font "standard"
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%
%% Default settings that are applied to TAB-indented lines.
%%
%tab 1 size 5, vgap 40, prefix "     ", icon arc "red" 50
%tab 2 size 4, vgap 35, prefix "            ", icon delta3 "blue" 40
%tab 3 size 3, vgap 35, prefix "                        ", icon dia "DarkViolet" 40
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page
%nodefault
%center, size 9, font "thick", back "white", fore "black"



Tor: 
%size 8
Next-generation Onion Routing


%size 7
Roger Dingledine
Nick Mathewson
Paul Syverson

%%The Free Haven Project
%%%font "typewriter", fore "blue"
%%http://freehaven.net/
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

Low-latency anonymity system

%leftfill
Deployed: 19 nodes, hundreds of users (?)

Many improvements on earlier design

Free software -- available source code

Design is not covered by earlier onion routing
patent

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

Perfect forward secrecy


Telescoping circuit

	negotiates keys at each hop

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%page
%%
%%Separation from "protocol cleaning"
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

No mixing, padding, traffic shaping (yet)


Please show us they're worth the usability tradeoff

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%page
%%
%%Many TCP streams can share one circuit
%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

Congestion control


Simple rate limiting

Plus have to keep internal nodes from overflowing

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

Directory servers


Approve new servers

Tell clients who's up right now

	plus their keys, location, etc

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

Variable exit policies


Each server allows different outgoing connections

E.g. no servers allow outgoing mail currently

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

End-to-end integrity checking


In previous onion routing, an insider could change
the text being transmitted:

"dir" => "rm *"

Even an external adversary could do this!

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

Rendezvous points


allow hidden services

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

Differences / limitations


We're TCP-only, not all IP (but we're user-space and very portable)

Not peer-to-peer

No protocol normalization

%%Not unobservable

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%page

We have working code


Plus a design document,
and a byte-level specification

%size 9
http://freehaven.net/tor/