Bay Area Security Research Summit 2015

April 10, 2015 — San Francisco

The Bay Area Security Research Summit is an annual student-led academic workshop for researchers at UC Berkeley and Stanford who study computer security and applied cryptography. Dropbox graciously provided the venue and catering for this year's event.


Time Title Speaker
2:00 pm Arrival + Welcome
2:15 pm How to Spread Rumours Anonymously Giulia Fanti, UCB
2:35 pm Privacy-Preserving Shortest Path Computation David Wu, Stanford
3:00 pm BlindBox: Deep Packet Inspection over Encrypted Data Justine Sherry, UCB
3:20 pm Break
3:30 pm Building a Key Directory with Verifiable Global Consistency Joe Bonneau, Stanford
3:55 pm On The Evaluation of Censorship Evasion Tools Sadia Afroz, UCB
4:15 pm PowerSpy: Location Tracking using Mobile Device Power Analysis Yan Michalevsky, Stanford
4:40 pm Smart Locks: Lessons for Securing Cyber-Physical Authentication
in the Internet of Things
Grant Ho, UCB


Talk Abstracts

"How to Spread Rumours Anonymously"

Speaker: Giulia Fanti (PhD student)

Anonymous messaging platforms, such as Secret, Whisper, and Yik Yak, allow people to share their thoughts without fear of judgment by friends, family, or the public. Such anonymous platforms are particularly useful in nations with authoritarian governments, where the right to free expression and sometimes the personal safety of message authors depend on anonymity. We address the problem of anonymously broadcasting a message over a network, such as a social network. Recent advances in rumor source detection imply that existing messaging protocols could allow a moderately strong adversary to infer the source of a message with high probability, using only knowledge of the underlying social graph and limited information about who saw the message. We introduce a novel messaging protocol, which we call adaptive diffusion, and show that it spreads messages quickly while hiding the source node with provable anonymity guarantees. In particular, when the underlying contact network is an infinite regular tree, nearly all users with the message are equally likely to have originated the message. We show through simulation that adaptive diffusion effectively hides the location of the source even when the graph is finite, irregular and has cycles.

"Privacy-Preserving Shortest Path Computation"

Speaker: David Wu (PhD student, Stanford)

Navigation is one of the most popular location-based services today. But in virtually all cloud-based navigation systems, the client must reveal her location or intended destination to the cloud in order to learn the fastest route. In this talk, I will describe a new protocol for computing shortest paths in road networks that provides privacy for both the client’s query and for the map provider’s routing data. First, I will describe an efficient method for compressing the next-hop routing matrices for road networks. Applying this method to the map of Los Angeles, I show that we can achieve over tenfold reduction in the representation size. Moreover, the structure of our compressed representation enables an efficient cryptographic protocol suitable for real-time navigation in cities. To conclude the talk, I will describe our implementation of our private routing protocol and discuss some of the benchmarks we performed on real road networks for major cities such as Washington D.C. and Los Angeles.

Joint work with Joe Zimmerman, Jeremy Planul, and John Mitchell.

"BlindBox: Deep Packet Inspection over Encrypted Data"

Justine Sherry (PhD student, UC Berkeley)

Many network middleboxes perform deep packet inspection, a set of useful tasks which examine packet payloads. These tasks include intrusion detection (IDS), exfiltration detec- tion, and parental filtering. However, a long-standing issue is that once packets are sent over https, the middleboxes can no longer accomplish their tasks because the payloads are encrypted. Hence, one is faced with choosing at most one of two desirable properties: the functionality of the middleboxes and the privacy of encryption.

We propose BlindBox, a novel system that for the first time enables both properties together. The approach of Blind- Box is to perform the deep-packet inspection directly on the encrypted traffic. We demonstrate how BlindBox enables applications such as IDS, exfiltration detection and parental filtering; BlindBox supports real rulesets from both open source (Snort) DPI systems as well as rulesets from industrial DPI systems developed by two security companies. While BlindBox’s performance is not yet ready for real deployment, BlindBox is nearly practical and improves performance by more than 106 times as compared to a direct application of cryptography.

"Building a key directory with verifiable global consistency"

Speaker: Joe Bonneau (Post-doc, Stanford)
Slides: HTML, PDF

Mass data collection can only be countered by mass encryption. Apple iMessage and WhatsApp have shown that end-to-end encryption can be deployed transparently to messaging applications with hundreds of millions of users, but key management remains centralized in both systems and vulnerable to manipulation by the service provider. This talk will discuss a new protocol to address this by allowing a central key server to prove to all participants that it is serving keys consistently to all users. Our proposed protocol, CONIKS, has been developed in consort with several major messaging providers and we are expecting significant deployment in 2015. This partnership has introduced us to many difficult practical problems, including allowing participants to efficiently verify the consistency of their own data, minimizing bandwidth requirements, allowing new users to be enrolled with no latency, and ensuring privacy by not leaking the list of usernames in the system or the total number of users in the system.

"On The Evaluation of Censorship Evasion Tools"

Speaker: Sadia Afroz (Post-doc, UC Berkeley)

In recent years, government censorship of the Internet has been prevalent in many countries including China and Iran. Researchers have deployed numerous censorship evasion tools to provide open access to information. Censors, in return, blocked access to the evasion tools. In this talk, I will focus on censorship of Tor. I will discuss the censorship mechanisms used to block Tor and contrast it with the evaluation criteria used to evaluate evasion tools. The goal of the discussion is to illuminate that the criteria used to evaluate a proposed system are different from the criteria used to block an evasion tool in the real world. Finally, I'll propose practical evaluation criteria.

"PowerSpy: Location Tracking using Mobile Device Power Analysis"

Speaker: Yan Michalevsky (PhD student, Stanford)
Slides: HTML, PDF

Modern mobile platforms like Android enable applications to read aggregate power usage on the phone. This information is considered harmless and reading it requires no user permission or notification. We show that by simply reading the phone's aggregate power consumption over a period of a few minutes an application can learn information about the user's location. Aggregate phone power consumption data is extremely noisy due to the multitude of components and applications that simultaneously consume power. Nevertheless, by using machine learning algorithms we are able to successfully infer the phone’s location. We discuss several ways in which this privacy leak can be remedied.

"Smart Locks: Lessons for Securing Cyber-Physical Authentication in the Internet of Things"

Speaker: Grant Ho (PhD student, UC Berkeley)

Recently, many lock manufacturers and startups have begun selling commodity home smart locks: cyber-physical devices that replace traditional door locks with electronically-controlled deadbolts. We present five categories of general attacks against smart lock systems and analyze the security of two commercially-available smart locks with respect to these attacks. Our security analysis reveals that flaws in the predominant system design used by many existing smart locks leaves them vulnerable to these attacks.

While several of these vulnerabilities can be remedied by the defenses we suggest, a number of attacks do not have clear, known solutions and may require significant system design changes; in some cases, there also appears to be a tension between usability and security. These weaknesses highlight interesting problems for future research on the security of the Internet of Things.

We take a first step towards resolving one of these open problems by proposing Touch Verified Intent Communication, a mechanism that achieves strong security guarantees without disrupting the user's natural behavior and interaction process. I'll also discuss our earlier (failed) approaches to resolve this particular tension between security and usability and the insights gained from these experiences.

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