Side Channels and Clouds: New Challenges in Cryptography

Emerging trends in computation such as cloud computing, virtualization, and trusted computing require that computation be carried out in remote and hostile environments, where attackers have unprecedented access to the devices, the data and the programs. This poses new problems and challenges for cryptography. In this talk, I will present two such challenges, and my recent work towards solving them. 1. Protecting against Side-channel Attacks: Computing devices leak information to the outside world not just through input-output interaction, but through physical characteristics of computation such as power consumption, timing, and electro-magnetic radiation. Such information leakage betrays information about the secrets stored within the devices, and has been successfully utilized to break many cryptographic algorithms in common use. These attacks are commonly called side-channel attacks. Side-channel attacks are particularly easy to carry out when the device is in the physical proximity of an attacker, as is often the case for modern devices such as smart-cards, TPM chips, mobile phones and laptops. In the first part of the talk, I will describe my recent work that lays the foundation of leakage-resilient cryptography ΓÇô the design of cryptographic schemes that protect against large classes of side-channel attacks. 2. Computing on Encrypted Data: Security in the setting of cloud computing involves a delicate balance of privacy and functionality: while the client must encrypt its data to keep it private from the server, it should also allow for the server to compute on the encrypted data. Can we simultaneously achieve these opposing goals? In the second part of the talk, I will describe an elementary construction of a cryptographic mechanism that allows computation on encrypted data (also called a fully homomorphic encryption scheme). Both these works leverage new mathematical techniques based on geometric objects called lattices.