Category Archives: Academics

What's Left for private Messaging

I had the privilege to address the annual Chaos Communication Congress (36C3) in Leipzig last week about the state and remaining issues in private communications.

The recording of the video has been made available by the CCC, and I have also posted the slides.

The TL;DR for me is that many of the trade-offs are balancing the stability of user experience with privacy mechanisms – and finding more ergonomic user experience interactions will be as important as new systems schemes are to improving the ecosystem.

I am particularly excited by the number of ongoing effort reducing trust in central servers. Many of the mechanistic trade-offs we face are due to the topology of our systems. With systems designed for fully anonymous interaction, like mixnets, PIR, and oblivious messaging, we can model and mitigate threats from much more realistic adversaries than we do with popular channels today. (For instance, consider an office which has received a whistle blowing message. If the receiving investigation wants to identify the source, they likely control both the local network, and have the ability to send messages to the account that initiated the conversation. Our current designs will find it quite difficult to protect a user from this scenario)

NextGen Korea Scholars

I had the incredible opportunity to spend the end of last week in Washington DC with the CSIS NextGen Scholars program meeting the US policy makers who define the US policy towards the DPRK.

It was fascinating to see the process has been put in place for weighing the different factors that go into these decisions, and how at the same time there really is truth to the almost inconceivable notion that the best any of us can hope for is that Trump and Kim Jong Un will have a successful summit and be able to make progress based on some unexpected personal trust.

I am hopeful I was able to offer some insight into what life is like in the country, and perhaps was able to offer some sense of the value provided by engagements like PUST.

Several tweets provide a sense of who we got to meet.

Ethics of Censorship Measurement

I gave a talk this past summer at DEFCON on the ethical quandary that continues to play a role in the academic discussion of network censorship measurement. Over the course of my phd studies, there was a significant arc of time where the community yielded to caution as the issues around ethics were better understood.

These issues have not gone away, and in the intervening six months since this talk, we’ve seen new groups re-develop techniques deemed problematic by the prevailing winds of the academic community.

Watch on Youtube


Corporate Censorship

One of the most interesting lines of inquiry within the Censored Planet project at the University of Michigan is trying to pull apart the different actors involved in Internet  censorship. One of the interesting quirks is that a significant factor in why content might not be available to users is that the web publisher themselves have limited who they’ll respond to.

This relates to existing phenomenons like increased balkanization of the web, where regions and nations promote domestic services and networks, but is as much a function of where lucrative markets are and a reaction to the background of fraud and malicious online traffic.

One outcome of this research is a set of measurements looking at how and where CDNs limit access, that will be presented tomorrow at IMC.

Like many parts of the Internet, a take-away here is that attribution is hard.

Open Letter to the Cuba Internet Task Force

The following is a response to an invitation to participate in the recently formed Cuba Internet Task Force.

Task Force Representatives:
I will not be joining the Cuba Internet Task Force, or Subcommittees, because I believe the harm done by the existence of these committees outweighs any potential benefit of the recommendations that can come from them.

In recent years, Cuba has increasingly normalized Internet usage, through expansion and cost reduction of WiFi, through the advent of AirBNB as a major source of tourism revenue, and through growing traffic capacity.

In the scope of my work, I have documented the flourishing community wireless networks operating in tandem with official Internet service from ETECSA. These community efforts already address the “last mile” problem, and it is not hard to imagine the future where they are consolidated or integrated to provide Internet-to-the-home for many more Cubans.

These efforts are hindered by the perception by the Cuban government that the Internet and its associated ‘freedom’ are being forced upon them by the United States. In the wake of the creation of this task force, Cuban media has focused on the implied pressure, and private individuals in the Cuban technology sector have come under increased scrutiny.

Instead of attempting to influence the policies of another sovereign nation, I encourage us to reflect more on our internal policies. US government sanctions currently require a wide range of US-based education and reference sites from blocking Cuban traffic. Likewise, limitations preventing Cubans from connecting to US-invested undersea cables are partially responsible for the scarcity and cost of Cuban Internet connections. Reducing these sanctions can allow Cubans to become a market for US companies, and will provide additional incentives for widespread connectivity across the country.

Initial Measurements of the Cuban Street Network

Internet access in Cuba is severely constrained, due to limited availability, slow speeds, and high cost. Within this isolated environment, technology enthusiasts have constructed a disconnected but vibrant IP network that has grown organically to reach tens of thousands of households across Havana. We present the first detailed characterization of this deployment, which is known as the SNET, or Street Network. Working in collaboration with SNET operators, we describe the network’s infrastructure and map its topology, and we measure bandwidth, available services, usage patterns, and user demographics. Qualitatively, we attempt to answer why the SNET exists and what benefits it has afforded its users. We go on to discuss technical challenges the network faces, including scalability, security, and organizational issues. To our knowledge, the SNET is the largest isolated community-driven network in existence, and its structure, successes, and obstacles show fascinating contrasts and similarities to those of the Internet at large.


The Internet in Cuba: A Story of Community Resilience. Chaos Communication Congress. 2017


P Pujol, Eduardo E., Will Scott, Eric Wustrow, and J. Alex Halderman. “Initial measurements of the cuban street network.” In Proceedings of the 2017 Internet Measurement Conference, pp. 318-324. ACM, 2017. Slides