Talks
"Guardians of the Onion: Ensuring the Health and Resilience of the Tor Network"
Millions of internet users around the world rely on Tor to protect themselves from surveillance and censorship. While Tor-powered applications and the Tor protocol are widely known, the community behind it much less so. This talk will highlight the efforts to maintain a healthy and resilient Tor network, emphasizing the crucial role of a diverse, engaged community of relay operators.
We’ll discuss some recent news, the current state of the network, how we determine its health, and the strategies to strengthen its resilience, addressing challenges around sustainability and governance. If you're interested in understanding the inner workings of the Tor network, this talk is for you.
This talk is designed to give an overview of Tor's 'new and not-so-new' network health initiatives in response to some of the pressing questions that emerged from the recent reporting about Tor in Germany. After a brief introduction to "Tor," we will primarily focus on issues relating to the Tor network and its community, underscoring the critical importance of distributed trust, transparency, and engagement in maintaining a robust and healthy ecosystem.
We will provide a short overview of the fundamental components of the Tor network, detailing the different types of relays that constitute its infrastructure and the role these can have through their lifetime. We will emphasize that the network operates independently of the Tor Project, sustained by a decentralized, global community of contributors. By analyzing network metrics—such as relay distribution across countries and Autonomous Systems (AS)—we will highlight the current state of the network and identify opportunities for increasing geographic and technical diversity.
This is followed by an introduction to the concept of network health. We will define the term, assess the current condition of the Tor network, and showcase the different modes of participation. We will primarily consider this through the lens of an 'alleged' over-reliance on relay concentration in specific regions, such as Europe and the United States. These insights will inform a discussion on how a more geographically distributed network could improve resilience, enhance security, and increase overall functionality.
The talk will also address the primary challenges facing the Tor network: Sustainability remains a central concern, particularly with regard to maintaining a stable, secure, and decentralized network over time. Additionally, ensuring trust within the community is essential, especially in the face of potential misuse by malicious actors. We will explore the need for incentive structures that encourage the operation of relays while preserving the network’s independence and autonomy. We will review and debate initiatives the Tor Project has proposed to support a decentralized network without imposing centralized control.
In response to these challenges, we will propose several potential solutions. Expanding outreach efforts to regions outside the Global North could promote greater diversity in the relay community, thereby strengthening the network’s ability to resist censorship and external threats. We will also examine existing incentive frameworks that support relay operators. Furthermore, we will discuss the success of Snowflake proxies—widely adopted in regions with restrictive internet environments—and how it demonstrates how lowering the barrier to entry for running nodes can encourage broader participation from the community.
Finally, we will outline our strategy for ensuring the long-term health of the Tor network, focusing on governance, community engagement, and sustaining the network’s decentralized nature. We will conclude with a call to action, inviting participants to contribute to the continued sustainability and development of the Tor network.
"Measuring the Tor network"
tails
"Tech Demo - Privacy across ages and spaces"
This demo is about creating and running ephemeral .onion services to share websites or simple web applications. We present different use cases for onion services and a wrapper app that allows you to start a .onion and start sharing a static website or a web application. Because .onion services live on the Tor network, you do not need hosting or a public ip address to offer some service via .onion address. The .onion is hosted on your computer for the time you desire, allowing the people visiting your site to remain anonymous, and also you. We believe anonymity to be very important since it can free people, allowing them to decide how to expose themselves or to make themselves visible on their own terms.
venue: "Rightscon"
location: "Tunis, Tunisia"
"Privacy Web Docs"
Tor is an important tool providing privacy and anonymity online. The property of anonymity itself is more than just providing an encrypted connection between the source and the destination of a given conversation. There is in fact a lot of information that can be still learned by just observing encrypted communications. The Tor Browser was designed to provide privacy while surfing the web and defend users against both network and local forensic adversaries, There are two main categories of requirements for the Tor Browser: Security Requirements, and Privacy Requirements. Security Requirements are the minimum properties in order for a browser to be able to support Tor and similar privacy proxies safely. Privacy requirements are primarily concerned with reducing linkability: the ability for a user's activity on one site to be linked with their activity on another site without their knowledge or explicit consent. The Tor Browser is based on Mozilla's Extended Support Release (ESR) Firefox branch. We have a series of patches against this browser to enhance privacy and security. Browser behavior is additionally augmented through the Torbutton extension, and we also change a number of Firefox preferences from their defaults. This session is going to explore what tool and resources are missing for website and web applications to embrace more privacy friendly practices, and work seamlessly on Tor browser. We well answer some fundamental questions, like: - Why tor browser is slightly different from Firefox (or another browser) - Why does my app work differently in tor browser? What can I do to make it work smoothly? - How can I make my app compatible for people that do not use JS? - How can I configure an onion service? - What should I consider in order not to expose sensitive information about myself or visitors to my website? Code examples for css, js and backend configurations will be shared.
venue: "Internet Freedom Festival"
location: "Valencia, Spain"
"Onions adventures - FOSDEM"
How to use onion services and the Tor network in your web endeavors
Tor is an important tool providing privacy and anonymity online. The Tor network itself is only a part of what Tor is. Tor also provides privacy at the application level through the Tor Browser. The Tor Browser was designed to provide privacy while surfing the web and defend users against both network and local forensic adversaries. The same properties can be adopted by applications and services wishing to integrate the tor network in their architecture. Furthermore, onion services provide better authentication and assurance of who you are talking to. With onion services Tor can provide bi-directional anonymity by making it possible for users to hide their locations while offering various kinds of services, such as web publishing or an instant messaging server. This talk is going to explain how it is possible to integrate tor and build onion applications.
The property of anonymity itself is more than just providing an encrypted connection between the source and the destination of a given conversation. Encryption only prevents the content of the communication between Alice and Bob from becoming known. There is in fact a lot of information that can still be learned by just observing encrypted communications. For example, it is always possible to guess certain information by learning some properties of the conversation beyond just the content, such as the length of the conversation, or who was involved, or even guessing a group of people that communicate with a certain frequency. These properties are called metadata and can be used to describe information even when the full data is not available.
Anonymity is a broad concept, and it can mean different things to different groups. The main advertised property of the Tor network is that it provides strong anonymity given a variety of people using the network. For the Tor network to function properly and to satisfy users' needs, we need a certain degree of diversity. We need diversity in the nodes relays comprising the network and in the user population sending traffic through it. Lately, we have been introducing new traffic scheduling features in the network in order to solve problems, reduce congestion, and improve overall performance. The Tor network itself is only a part of what Tor is. Tor also provides privacy at the application level through the Tor Browser.
Other applications can also make use of the Tor network to be more secure. Onion services provide better authentication and assurance of who you are talking to. In this case, Tor can provide bi-directional anonymity by making it possible for users to hide their locations while offering various kinds of services, such as web publishing or an instant messaging server.
This talk is going to introduce what it does mean to do web development with privacy in mind. We will start by presenting a few example of applications that use onion services and follow up with tips on how to integrate onion services in your architecture and how to provide a seamless frontend experience for privacy-concerned people that prefer to use the Tor Browser.
venue: "FOSDEM"
location: "Brussels, Belgium"
"Onions in containers"
How Docker Containers Can Be Used to Spawn Onion Services, Securely and Anonymously, from Your Computer.
Tor is an important tool providing privacy and anonymity online. The property of anonymity itself is more than just providing an encrypted connection between the source and the destination of a given conversation. Encryption only prevents the content of the communication between Alice and Bob from becoming known. Onion Services offer bidirectional anonymity through Tor "rendezvous points," other Tor users can connect to these onion services each without knowing the other's network identity, just by sharing the onion service address. This talk is going to explain how we built a desktop app to allow users to start onion services with a click and share a website or a web app from their computer.
venue: "Docker Con EU"
location: "Barcelona, Spain"
"Onion adventures"
Tor is an important tool providing privacy and anonymity online. This talk is going to present what Tor is and how it works. We are also going to present new features that have been developed lately. Finally we are going to explain how we can build applications that use Tor.
venue: "Full Stack Fest"
location: "Barcelona, Spain"
"Peeling onions: understanding and using the Tor network"
Tor is an important tool providing privacy and anonymity online. The property of anonymity itself is more than just providing an encrypted connection between the source and the destination of a given conversation. There is in fact a lot of information that can be still learned by just observing encrypted communications. Anonymity is a broad concept, and it can mean different things to different groups. The main advertised property of the Tor network is that it provides strong anonymity given a variety of people using the network. The Tor network itself is only a part of what Tor is. Tor also provides privacy at the application level through the Tor Browser. This talk is going to present what Tor is and how it works. We are also going to present new features we have been developing lately. Finally we are going to explain how you can build applications that use Tor.
Tor is an important tool providing privacy and anonymity online. The property of anonymity itself is more than just providing an encrypted connection between the source and the destination of a given conversation. Encryption only prevents the content of the communication between Alice and Bob from becoming known.
There is in fact a lot of information that can still be learned by just observing encrypted communications. For example, it is always possible to guess certain information by learning some properties of the conversation beyond just the content, such as the length of the conversation, or who was involved, or even guessing a group of people that communicate with a certain frequency. These properties are called metadata and can be used to describe information even when the full data is not available.
Anonymity is a broad concept, and it can mean different things to different groups. The main advertised property of the Tor network is that it provides strong anonymity given a variety of people using the network. For the Tor network to function properly and to satisfy users' needs, we need a certain degree of diversity. We need diversity in the nodes comprising the network and in the user population sending traffic through it. Lately, we have been introducing new traffic scheduling features in the network in order to solve problems, reduce congestion and improve overall performance.
The Tor network itself is only a part of what Tor is. Tor also provides privacy at the application level through the Tor Browser.
Other applications can also make use of the Tor network to be more secure. In this case Tor can provide bi-directional anonymity by making it possible for users to hide their locations while offering various kinds of services, such as web publishing or an instant messaging server. The next generation onion services have been recently launched in alpha and we are excited to touch on some of the new features that have been introduced on the old hidden service design.
venue: "FOSDEM"
location: "Brussels, Belgium"
"Ubiquitous tracking of users’ browsing habits."
In the early age of the internet users enjoyed a large level of anonymity. At the time web pages were just hypertext documents; almost no personalisation of the user experience was offered. The Web today has evolved as a world wide distributed system following specific architectural paradigms. On the web now, an enormous quantity of user generated data is shared and consumed by a network of applications and services, reasoning upon users expressed preferences and their social and physical connections. Advertising networks follow users' browsing habits while they surf the web, continuously collecting their traces and surfing patterns. We analyse how users tracking happens on the web by measuring their online footprint and estimating how quickly advertising networks are able to profile users by their browsing habits.
Slides
venue: "Vienna University of Technology (TU)"
location: "Vienna, Austria"
"Mass surveillance in dating apps."
Proximity-based social applications let users interact with people that are currently close to them, by revealing some information about their preferences and whereabouts. This information is acquired through passive geo-localisation and used to build a sense of serendipitous discovery of people, places and interests. Unfortunately, while this class of applications opens different interactions possibilities for people in urban settings, obtaining access to certain identity information could lead a possible privacy attacker to identify and follow a user in their movements in a specific period of time. The same information shared through the platform could also help an attacker to link the victim's online profiles to physical identities. We analyse a set of popular dating application that shares users relative distances within a certain radius and show how, by using the information shared on these platforms, it is possible to formalise a multilateration attack, able to identify the user actual position. The same attack can also be used to follow a user in all their movements within a certain period of time, therefore identifying their habits and Points of Interest across the city. Furthermore we introduce a social attack which uses common Facebook likes to profile a person and finally identify their real identity.
venue: "Aalto Univerisity"
location: "Helsinki, Finland"
"Personal tracking devices"
In the post-NSA world it is important to understand the magnitude of our online activities in order to take informative decisions on our ubiquitous shared lives. Personal Tracking Devices is the result of a two years long study on tracking technologies and the inherent nature of the web and telecommunication networks in general. The study, conducted as part of Ph.D. research in privacy and security at UPC Barcelona Tech, collected a large amount of metadata to raise awareness on the footprints left by users on the web and through mobile apps.
venue: "CCC"
location: "Hamburg, Germany"