1. NETWORK SECURITY HERD: A SCALABLE, TRAFFIC ANALYSIS RESISTANT ANONYMITY NETWORK FOR VOIP SYSTEMS JINGTAO YAO JIAJUN LI ACM HORNORED CLASS

2. CONFERENCE & AUTHORS ACM SIGCOMM Conference 2015 Security, Privacy, and Censorship Stevens Le BlondMPI-SWS, Saarbrucken, Germany David ChoffnesNortheastern University, Boston, MA, USA William CaldwellMPI-SWS, Saarbrucken, Germany Peter Druschel MPI-SWS, Saarbrucken, Germany Nicholas MerrittMPI-SWS, Saarbrucken, Germany

3. BACKGROUND——VOIP VoIP——Voice over Internet Protocol Voice over IP (VoIP) is a methodology and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. Other terms commonly associated with VoIP are IP telephony, Internet telephony, broadband telephony, and broadband phone service.

4. BACKGROUND——TOR Tor——free software for enabling anonymous communication Onion routing is implemented by encryption in the application layer of a communication protocol stack, nested like the layers of an onion. Tor encrypts the data, including the destination IP address, multiple times and sends it through a virtual circuit comprising successive, randomly selected Tor relays.

5. BACKGROUND——TOR Each relay decrypts a layer of encryption to reveal only the next relay in the circuit in order to pass the remaining encrypted data on to it. The final relay decrypts the innermost layer of encryption and sends the original data to its destination without revealing, or even knowing, the source IP address. Because the routing of the communication is partly concealed at every hop in the Tor circuit, this method eliminates any single point at which the communicating peers can be determined through network surveillance that relies upon knowing its source and destination.

6. BACKGROUND——TOR

7. BACKGROUND——DEMAND many nation states use Internet surveillance to monitor and repress critics western democracies conduct mass surveillance VPN, Skype, traffic analysis

8. RELATED WORK Burner phones VoIP services Anonymity networks Traffic analysis resistant anonymity

9. RELATED WORK——ANONYMITY NETWORKS accessing a VoIP service via an anonymity network like Tor Unfortunately, the typical delays incurred by Tor circuits are too high for adequate VoIP call quality. VoIP may use Tor-like (onion routing) anonymity network and solve the delay

10. HERD ARCHITECTURE

11. NODES Client Superpeer Mix Zone

12. LIKE STATICS ROUTING Geo-related zone and routing Superpeer with Mix Reduce delay Dynamic channel allocation

13. ENCRYPTION Mix->Mix Superpeer->Mix Mix->Superpeer->Mix Superpeer->Client

14. TRAFFIC CONTROL Each client sends and receives at a constant rate equivalent to a small number of voice calls on their SP link(s). The links connecting SPs to their mixes carry bidirectional, encrypted and padded traffic at a rate that is a multiple of the VoIP base rate. The mixes are fully connected by a set of encrypted and padded links.

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