25 research outputs found
Vuvuzela: scalable private messaging resistant to traffic analysis
Private messaging over the Internet has proven challenging to implement, because even if message data is encrypted, it is difficult to hide metadata about who is communicating in the face of traffic analysis. Systems that offer strong privacy guarantees, such as Dissent [36], scale to only several thousand clients, because they use techniques with superlinear cost in the number of clients (e.g., each client broadcasts their message to all other clients). On the other hand, scalable systems, such as Tor, do not protect against traffic analysis, making them ineffective in an era of pervasive network monitoring.
Vuvuzela is a new scalable messaging system that offers strong privacy guarantees, hiding both message data and metadata. Vuvuzela is secure against adversaries that observe and tamper with all network traffic, and that control all nodes except for one server. Vuvuzela's key insight is to minimize the number of variables observable by an attacker, and to use differential privacy techniques to add noise to all observable variables in a way that provably hides information about which users are communicating. Vuvuzela has a linear cost in the number of clients, and experiments show that it can achieve a throughput of 68,000 messages per second for 1 million users with a 37-second end-to-end latency on commodity servers.National Science Foundation (U.S.) (Award CNS-1053143)National Science Foundation (U.S.) (Award CNS-1413920
Practical Traffic Analysis Attacks on Secure Messaging Applications
Instant Messaging (IM) applications like Telegram, Signal, and WhatsApp have
become extremely popular in recent years. Unfortunately, such IM services have
been targets of continuous governmental surveillance and censorship, as these
services are home to public and private communication channels on socially and
politically sensitive topics. To protect their clients, popular IM services
deploy state-of-the-art encryption mechanisms. In this paper, we show that
despite the use of advanced encryption, popular IM applications leak sensitive
information about their clients to adversaries who merely monitor their
encrypted IM traffic, with no need for leveraging any software vulnerabilities
of IM applications. Specifically, we devise traffic analysis attacks that
enable an adversary to identify administrators as well as members of target IM
channels (e.g., forums) with high accuracies. We believe that our study
demonstrates a significant, real-world threat to the users of such services
given the increasing attempts by oppressive governments at cracking down
controversial IM channels.
We demonstrate the practicality of our traffic analysis attacks through
extensive experiments on real-world IM communications. We show that standard
countermeasure techniques such as adding cover traffic can degrade the
effectiveness of the attacks we introduce in this paper. We hope that our study
will encourage IM providers to integrate effective traffic obfuscation
countermeasures into their software. In the meantime, we have designed and
deployed an open-source, publicly available countermeasure system, called
IMProxy, that can be used by IM clients with no need for any support from IM
providers. We have demonstrated the effectiveness of IMProxy through
experiments