Remotely Keyed CryptoGraphics: Secure Remote Display Access Using (Mostly) Untrusted Hardware

Debra Cook, Ricardo Baratto, Angelos Keromytis

Proceedings of the 7th International Conference on Information and Communications Security (ICICS 2005), Beijing, China, December 10-13, 2005, pp. 363-375

Abstract

Software that covertly monitors user actions, also known as spyware, has become a first-level security threat due to its ubiquity and the difficulty of detecting and removing it. Such software may be inadvertently installed by a user that is casually browsing the web, or may be purposely installed by an attacker or even the owner of a system. This is particularly problematic in the case of utility computing, early manifestations of which are Internet cafes and thin-client computing. Traditional trusted computing approaches offer a partial solution to this by significantly increasing the size of the trusted computing base (TCB) to include the operating system and other software. We examine the problem of protecting a user accessing specific services in such an environment. We focus on secure video broadcasts and remote desktop access when using any convenient, and often untrusted, terminal as two example appli- cations. We posit that, at least for such applications, the TCB can be confined to a suitably modified graphics processing unit (GPU). Specifically, to prevent spy- ware on untrusted clients from accessing the user’s data, we restrict the boundary of trust to the client’s GPU by moving image decryption into GPUs. This allows us to leverage existing capabilities as opposed to designing a new component from scratch. We discuss the applicability of GPU-based decryption in the two scenarios. We identify limitations due to current GPU capabilities and propose straightf

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Columbia University Department of Computer Science