| 
					
				 | 
			
			
				@@ -1,4 +1,3 @@ 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-% XXX Cite SS03 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				  
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 \documentclass[times,10pt,twocolumn]{article} 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 \usepackage{latex8} 
			 | 
		
	
	
		
			
				| 
					
				 | 
			
			
				@@ -212,11 +211,15 @@ security, and became useless if any node in the path went down 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 or rotated its keys.  In Tor, clients negotiate {\it rendezvous points} 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 to connect with hidden servers; reply onions are no longer required. 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				  
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+Unlike Freedom~\cite{freedom2-arch}, Tor does not require OS kernel 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+patches or network stack support.  This prevents us from anonymizing 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+non-TCP protocols, but has greatly helped our portability and 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+deployability. 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				  
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-Unlike Freedom~\cite{freedom2-arch}, Tor does not anonymize 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-non-TCP protocols---not requiring patches (or built-in support) in an 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-operating system's network stack has been valuable to Tor's 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-portability and deployability. 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+%Unlike Freedom~\cite{freedom2-arch}, Tor only anonymizes 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+%TCP-based protocols---not requiring patches (or built-in support) in an 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+%operating system's network stack has been valuable to Tor's 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+%portability and deployability. 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				  
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 We have implemented all of the above features except rendezvous 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 points. Our source code is 
			 | 
		
	
	
		
			
				| 
					
				 | 
			
			
				@@ -227,7 +230,7 @@ earlier versions of Onion Routing. 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 We have deployed a wide-area alpha network 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 to test the design, to get more experience with usability 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 and users, and to provide a research platform for experimentation. 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-As of this writing, the network stands at sixteen nodes in thirteen 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+As of this writing, the network stands at eighteen nodes in thirteen 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 distinct administrative domains on two continents. 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				  
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 We review previous work in Section~\ref{sec:related-work}, describe 
			 | 
		
	
	
		
			
				| 
					
				 | 
			
			
				@@ -273,7 +276,8 @@ delivery confirmation. But because these designs typically 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 involve many packets that must be delivered quickly, it is 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 difficult for them to prevent an attacker who can eavesdrop both ends of the 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 communication from correlating the timing and volume 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-of traffic entering the anonymity network with traffic leaving it.  These 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+of traffic entering the anonymity network with traffic leaving it \cite{SS03}. 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+These 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 protocols are similarly vulnerable to an active adversary who introduces 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 timing patterns into traffic entering the network and looks 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 for correlated patterns among exiting traffic. 
			 | 
		
	
	
		
			
				| 
					
				 | 
			
			
				@@ -1520,8 +1524,8 @@ in~\cite{mix-acc}.\\ 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 \Section{Early experiences: Tor in the Wild} 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 \label{sec:in-the-wild} 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				  
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-As of mid-January 2004, the Tor network consists of 17 nodes 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				-(15 in the US, 2 in Europe), and more are joining each week as the code 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+As of mid-January 2004, the Tor network consists of 18 nodes 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				+(16 in the US, 2 in Europe), and more are joining each week as the code 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 matures.\footnote{For comparison, the current remailer network 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 has about 30 reliable nodes. We haven't asked PlanetLab to provide 
			 | 
		
	
		
			
				 | 
				 | 
			
			
				 Tor nodes, since their AUP wouldn't allow exit nodes (see 
			 |