신뢰적 실행 환경에서 보안적인 점진적인 업데이트 방식

Abstract

A Secure Incremental Update Method in Trusted Execution Environment

Kim, Hyun Sung Major in Computer Science and Engineering The Graduate School of Engineering Hanyang University

Mobile devices such as Smart-phone and Tablet become increasingly prevalent in our daily life. There are a number of reasons why people prefer mobile devices to desktop computer. One of the key reasons is versatile functionalities. The term ‘Rich Execution Environment(REE)’is coined to describe the versatile features in the mobile devices.

The REE brings flexibility and capability, but at the same time leaves a device vulnerable to a wide range of security threats. Especially, the applications related with piece of valuable information like money, confidential company information and private bio-data have a potential risk. So to keep its valuable information from unauthorized entities, trusted environment is getting critical from an individual and industrial point of view. In the same vein, many device vendors try to apply to secure framework at their product. To provide an integrated trusted system, an association called GlobalPlatform has been making effort to standardize the Trusted Execution Environment.

In the released TEE specification, a number of functions have changed more efficiently over time. One of functionalities is about update function. It is one of the most important features. If it is not, all devices cannot upgrade program itself. In other words, it takes additional cost and time to cover software vulnerabilities. And furthermore, it is difficult to give trust to those who use a trusted service. But the current self-update process in Trusted Execution Environment has a room for improvement economically and efficiently.

So I’ll supplement this update function’s weakness with incremental algorithm in the aspect of efficiency, performance and cost. In this document, I’ll describe how to apply to incremental update algorithm at Trusted Execution Environment without big changes. By applying to incremental update method, the performance for update is improved. And also the cost of transferring data is reduced at least over 60% in a general case.