Archive for the 'Privacy' Category

Apple and the FBI

Thursday, February 25th, 2016

I’m quoted in this article on the controversy over the FBI’s requests to Apple for assistance in unlocking an iPhone used by one of the San Bernardino terrorists: Unlocking Terrorist’s iPhone Won’t Risk Your Security, Discovery News, 24 February 2016.

“Backdoors are complicated and impossible technical challenges and would risk everyone’s privacy,” Evans said. “But what the FBI is asking for is different from what Apple says the FBI is asking for.”

For the most part, I think the article gets things right. It is very misleading to conflate what the FBI has asked for here with a cryptographic backdoor that would indeed dangerously risk everyone’s privacy and security. I covered some of the technical aspects of this in my introductory computing course last week.

Computer Science Grad Stands Watch for Users of Google’s Popular Browser

Tuesday, December 8th, 2015

Adrienne Porter Felt (BSCS 2008) returned to UVa last Friday as a Distinguished Alumni Speaker. UVa Today published this article:

Computer Science Grad Stands Watch for Users of Google’s Popular Browser
, UVa Today, 7 December 2015.

Adrienne Porter Felt’s job is to keep you secure on Chrome.

Felt, 29, who earned a computer science degree from the University of Virginia in 2008, leads the usable security team at Google working on the popular Internet browser.

Taking Evans’ offer for a research project was a turning point in Felt’s life, showing her something she liked that she could do well.

“It turned out that I really loved it,” she said. “I like working in privacy and security because I enjoy helping people control their digital experiences. I think of it as, ‘I’m professionally paranoid so that other people don’t need to be.’”

Karsten Nohl Interview

Monday, August 31st, 2015

Atlas Obscura has an article about Karsten Nohl (PhD 2009):
Exit Interview: I’m A Crypto-Specialist Working To Secure the Internet For A Billion People, Jeremy Berke, 28 July 2015.

One of the things we’re building is a PayPal competitor–with a modest target of having a few hundred million customers. Everything in India is always on a massive scale. If you could get rid of PayPal passwords, and instead just have a fingerprint–if you could pay for goods at a store with just your fingerprint, that would simplify people’s lives a lot. It would also have the secondary effect of saving some of the security problems, like phishing, that we currently encounter. And this government database is a huge enabler.

If we already have a mandate to collect everybody’s fingerprints, why not use it in the customer’s benefit? The privacy risk is always there. That’s the law and I can’t argue with that. But if the law is already creating this risk, why not create opportunity in the same step?

Understanding and Monitoring Embedded Web Scripts

Thursday, March 26th, 2015

Modern web applications make frequent use of third-party scripts, often in ways that allow scripts loaded from external servers to make unrestricted changes to the embedding page and access critical resources including private user information. Our paper describing tools to assist site administrators in understanding, monitoring, and restricting the behavior of third-party scripts embedded in their site, and what we’ve learned by using them, is now available: Yuchen Zhou and David Evans, Understanding and Monitoring Embedded Web Scripts, IEEE Symposium on Security and Privacy 2015.

Yuchen will present the paper at the Oakland conference (in San Jose) this May.

Project Site:

Who Does the Autopsy?

Wednesday, March 25th, 2015

This (perhaps somewhat oversensationalized) article in Slate draws from Nate Paul’s research on medical device security: If you Die after Someone Hacks Your Glucose Monitor Who Does the Autopsy? (Slate, 13 March 2015).

According to researchers at the Oak Ridge National Laboratory, in 2003 and 2009 respectively, the “Slammer” and “Conficker” worms had each successfully infected networked hospital systems responsible for monitoring heart patients. Since the days of Slammer and Conficker, malware has since become even more sophisticated, and a Trojan with a specifically engineered piece of malicious code, could cause harm to numerous patients around the world simultaneously.

While a small community of researchers, and even some government regulators, such as the FDA and FTC, have begun to pose important questions about the privacy and security implications of incorporating computer technology into biological systems, so far law enforcement and criminal justice authorities have been mostly absent from any substantive conversations.

iDash Competition Winner

Tuesday, March 17th, 2015

Congratulations to Samee Zahur for winning the iDash Secure Genomics competition (Hamming Distance challenge task), sponsored by Human Longevity, Inc. A video of the event is available at

Samee’s solution was built using Obliv-C, and the code will be posted soon.

Two Halves Make a Whole!

Monday, September 29th, 2014

Surprisingly, it is possible to reduce the data needed for a garbled gate to only two ciphertexts per gate, while preserving free xors. The scheme for doing that is described in our paper, Two Halves Make a Whole: Reducing Data Transfer in Garbled Circuits using Half Gates by Samee Zahur and Mike Rosulek and David Evans (now available on eprint).

Abstract. The well-known classical constructions of garbled circuits use four ciphertexts per gate, although various methods have been proposed to reduce this cost. The best previously known methods for optimizing AND gates (two ciphertexts; Pinkas et al., ASIACRYPT 2009) and XOR gates (zero ciphertexts; Kolesnikov & Schneider, ICALP 2008) were incompatible, so most implementations used the best known method compatible with free-XOR gates (three ciphertexts; Kolesnikov & Schneider, ICALP 2008). In this work we show how to simultaneously garble AND gates using two ciphertexts and XOR gates using zero ciphertexts, resulting in smaller garbled circuits than any prior scheme. The main idea behind our construction is to break an AND gate into two half-gates — AND gates for which one party knows one input. Each half-gate can be garbled with a single ciphertext, so our construction uses two ciphertexts for each AND gate while being compatible with free-XOR gates. The price for the reduction in size is that the evaluator must perform two cryptographic operations per AND gate, rather than one as in previous schemes. We experimentally demonstrate that our garbling scheme leads to an overall decrease in time (up to 25%), bandwidth (up to 33%), and energy use (up to 20%) over several benchmark applications. We also initiate a study of lower bounds for garbled gate size, and show that our construction is optimal for a large class of garbling schemes encompassing all known practical garbling techniques.

Congratulations Samee Zahur!

Friday, May 2nd, 2014

Samee Zahur passed in PhD Proposal on Abstractions for Data Oblivious Programs. The abstract is:

While many recent papers have demonstrated the feasibility of secure computation for various interesting applications, such techniques have not yet been widely adopted outside of the research community. In the thesis proposed here, we try to reduce one aspect of this entry barrier: software abstractions. We motivate the problem by showing how secure computation necessarily requires redesigning of even simple software abstractions such as language control structures and data structures. First, we propose a new language that can be easily extended by other researchers for purposes of their investigations. Then, we propose new constructions for common data structures that are efficient in this execution model. Finally, we propose to develop new optimizations for ORAM structures to enable faster computations in the RAM model. Our preliminary investigations are already showing promising results. We have implemented a prototype compiler for our new language that provides significantly higher flexibility compared to existing systems. We demonstrate this flexibility by showing that our language allows implementation of various library-based features that have, in the past, always used compiler modifications in other languages. We have also shown constructions of data structures that can provide over 10x speed improvement even on small data sizes.

Congratulations to Samee on successfully presenting his PhD Proposal. Samee will be spending the summer at Microsoft Research (Redmond).

Multi-Party Computation in 2029

Friday, February 21st, 2014

I gave a keynote talk at the Applied Multi-Party Computation workshop at Microsoft Research Redmond on Multi-Party Computation in 2029: Boom, Bust, or Bonanza?. Despite the risk of being proved horribly wrong in 15 years, my slides are here (also available as [PPTX] and as a video):

There are well-written summaries of the talk by Mahnush Movahedi and Mahdi Zamani and the Aarhus Crypto Group.

Karsten Nohl visits UVa

Friday, November 1st, 2013

Karsten Nohl, who complete a PhD in our group in 2009, is visiting UVa this week. UVa Today has an article: Renowned ‘White Hat Hacker’ to Speak on Real-World Security Holes:

University of Virginia graduate Karsten Nohl, one of the world’s most famous “white hat computer hackers,” will speak Friday at 3:30 p.m. in Rice Hall, room 130, about lessons learned from the security holes that he and fellow researchers have uncovered in mobile phones, wireless car keys and other technology used by billions of people everyday.

Nohl first made international headlines in 2008, while still a computer engineering doctoral student at U.Va., for research that exposed vulnerabilities in the world’s most popular smartcard, used by millions of people to pay fares on several major mass-transit systems around the world, including the London Underground and the Boston subway.

Such cards utilize miniscule wireless computer chips, about the size of a grain of rice, called RFIDs, short for “radio-frequency identification.” They send and receive information over short distances (generally 10 feet or less) via very low-power radio waves.

As an ethical security researcher, often called a “white hat hacker,” Nohl exposes vulnerabilities to spur improvements in the systems that he researches. He now does such work around the world as the founder and director of research at Security Research Labs in Berlin.

To prevent those with nefarious purposes from exploiting security holes he uncovers, Nohl typically withholds key details of the exploit and discloses his findings only months after sharing his research with the relevant manufacturers or trade organizations to allow them to roll out upgrades or countermeasures to mitigate the security risk.

Since graduating from U.Va. in August 2008, Nohl has gone on to discover and demonstrate two key security vulnerabilities in mobile phones – encryption flaws in both the GSM protocol that most cell phones use to communicate with cell towers, and in SIM cards, the tiny “subscriber identity module” chip in every phone that identifies and authenticates the phone.

Both discoveries generated worldwide media coverage.

As just one example of possible ramifications, the latter security hole could allow a malicious hacker to send a virus through a text message, which could then allow the hacker to eavesdrop on calls or make purchases through mobile payment systems.

“Karsten has had an outstanding impact in analyzing how cryptography gets used in the real world and demonstrating what goes wrong when important engineering principles are not followed carefully,” said computer science professor David Evans, Nohl’s former doctoral adviser and a co-organizer of Friday’s talk. “The vulnerabilities he has identified in RFID algorithms, GSM encryption and SIM cards impact billions of devices most of us use every day, and it’s really important that people understand the security weaknesses in these systems and that vendors work to improve them. Karsten’s work is a fundamental step toward those goals.”

Nohl’s talk will discuss how security exploits with real-world implications are usually enabled by not just one design flaw, but by deviations from best practices on multiple design layers. Protection designs that focus on a single security function and neglect complementary layers are more prone to compromise, Nohl will argue, with examples from his own research on three widely deployed technologies – cell phones, car keys and smartcards.

“Real-world cryptographic systems rarely meet academic expectations, with most systems being shown ‘insecure’ at some point,” Nohl said in an email description of his talk. “At the same time, our IT-driven world has not yet fallen apart, suggesting that many protection mechanisms are ‘secure enough’ for how they are employed.”

The talk will be followed by a reception in the fourth-floor atrium of Rice Hall.

The event is co-sponsored by the departments of Computer Science and Electrical and Computer Engineering, which jointly administer U.Va.’s computer engineering Program in the School of Engineering and Applied Science.