CWI Cryptology Group

Abstract: Traditionally, cryptographers assume that the secret keys are totally hidden from the adversary,and that the cryptographic algorithms are run “correctly” with no errors. Unfortunately, in reality there are various real-world physical attacks, which render this assumption false. These include leakage attacks, such as, timing, power, and acoustic attacks, which allow an adversary to (continually) leak information about the secret keys. In addition, there are various tampering attacks, including heat and EM radiation attacks, which allow an adversary to (continually) tamper with system. Recently, there has been a vast and growing body of work, which try to secure cryptographic systems against leakage attacks. However, there have been quite few results trying to protect systems against tampering attacks. In this talk, I will focus on the goal of trying to protect cryptographic systems against tampering attacks. I will focus on two recent results. One which shows how to construct encryption and signature schemes that are secure against an adversary that continually leaks and tampers (arbitrarily) with the secret key. The second result allows the adversary to tamper with the algorithm itself (as opposed to tamper only with the secret key), but guarantees security only against specific monotone faults. The first result is based on joint work with Bhavana Kanukurthi and Amit Sahai, and the second result is based on joint work with Allison Lewko, and Anup Rao.