Alpirez Bock Estuardo

Aalto university, Finland

Title:

White-Box Cryptography – Security Goals and Foundations

Abstract:

The white-box attack model was introduced in 2002 by Chow, Eisen, Johnson and van Oorschot.  In this attack model, we consider an adversary who gets access to the implementation code of a cryptographic algorithm with an embedded secret key. Additionally, the adversary is assumed to be in control of the execution environment of the implementation. White-box cryptography aims to maintain an implementation secure, even in the presence of such a strong adversary. White-box crypto has been widely deployed to protect digital rights management (DRM) applications and more recently, mobile payment applications. Since its introduction, a number of candidate designs for white-box AES and DES have been proposed. Unfortunately, all of these candidates have been subject to key extraction attacks, and it is not clear which level of security white-box cryptographic implementations can achieve in real life.

In this lecture, we will study the foundations of white-box cryptography, explaining its application scenarios and its security goals. As we explain, the security properties expected from a white-box program may vary depending on the use case we are considering. In this line, we will study formal security notions for white-box cryptography introduced in the literature and discuss their usefulness. Additionally, we will take a look at provably secure constructions which achieve security in these white-box models. While some constructions may achieve security under strong assumptions (e.g. indistinguishability obfuscation), these feasibility results serve as a conceptual validation for how white-box crypto is implemented in real life. Finally, we will take a look at popular attacks on white-box implementations of AES and show how their effectiveness is reflected on recent capture-the-flag competitions.

Bio of Alpirez Bock Estuardo:

Estuardo is a post-doctoral researcher at the department of Mathematics and Systems Analysis at Aalto University in Finland. He recently obtained his PhD under the supervision of Chris Brzuska, co-advised by Wil Michiels. His research focuses on definitional studies for white-box cryptography, as well as on the design of automated attacks on white-box cryptographic implementations. Before, Estuardo was an employee at the Leibniz Institute for High Performance Microelectronics IHP, where he worked on the design and implementation of hardware accelerators for elliptic curve cryptography in the light of side channel analysis attacks.

http://math.aalto.fi/~alpiree1