{Seminar} @ CDS: 19th January : “Metadata-private voice communication over untrusted infrastructure”

Metadata from voice calls, such as the knowledge of who is communicating with whom, contains rich information about people’s lives. Indeed, it is a prime target for powerful adversaries such as nation states. Existing systems that hide voice call metadata either require trusted intermediaries in the network or scale to only tens of users. This paper describes the design, implementation, and evaluation of Addra, the first system for voice communication that hides metadata over fully untrusted infrastructure and scales to tens of thousands of users. At a high level, Addra follows a template in which callers and callees deposit and retrieve messages from private mailboxes hosted at an untrusted server. However, Addra improves message latency in this architecture, which is a key performance metric for voice calls. First, it enables a caller to push a message to a callee in two hops, using a new way of assigning mailboxes to users that resembles how a post office assigns PO boxes to its customers. Second, it innovates on the underlying cryptographic machinery and constructs a new private information retrieval scheme, FastPIR, that reduces the time to process oblivious access requests for mailboxes. An evaluation of Addra on a cluster of 80 machines on AWS demonstrates that it can serve 32K users with a 99-th percentile message latency of 726 ms — a 7x improvement over a prior system for text messaging in the same threat model.

BIOGRAPHY

Divy Agrawal is a Professor of Computer Science at the University of California at Santa Barbara. His research interests are in the areas of databases, distributed systems, cloud computing, and big data infrastructures and analysis. He is a Fellow of the ACM, the IEEE, and the AAAS. Professor Agrawal is the recipient of the UCSB Academic Senate Award for Outstanding Graduate Mentoring. He is serving as the Chair of ACM Special Interest Group on Management of Data (ACM SIGMOD).

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About: The IBM-IISc Hybrid Cloud Lab (IIHCL) hosted at IISc is curating the Cloud Computing Seminar series with guest speakers from Industry and Academia speaking about the latest technologies and research on Cloud and edge computing, distributed computing systems, and AI/ML/Big Data platforms. More details at: http://iihcl.iisc.ac.in