Segumts

Tomás Balderas-Contreras René A. Cumplido-Parra

Security Architecture in UMTS Third Generation Cellular Networks

Reporte Técnico No. CCC-04-002 27 de febrero de 2004

© Coordinación de Ciencias Computacionales
INAOE

Luis Enrique Erro 1 Sta. Ma. Tonantzintla, 72840, Puebla, México.

Security Architecture in UMTS Third Generation Cellular Networks
Tom´s Balderas-Contreras Ren´ A.Cumplido-Parra a e Coordinaci´n de Ciencias Computacionales, o ´ Instituto Nacional de Astrof´ ısica, Optica y Electr´nica, o Luis Enrique Erro 1, Sta. Ma. Tonantzintla, 72840, Puebla, MEXICO balderas@inaoep.mx rcumplido@inaoep.mx

Abstract Throughout the last years there has been a great interest in developing and standardizing the technologies needed to achieve high speed transmission of data incellular networks. As a result, mobile communications technology has evolved amazingly during the last decades to meet a very demanding market. Third generation (3G) wireless networks represent the more recent stage in this evolutionary process; they provide users with high transmission bandwidths which allow them to transmit both audio and video information in a secure manner. This reportconcerns a specific implementation of the 3G requirement specification: Universal Mobile Telecommunications System (UMTS), which is considered to be the most important of the 3G proposals. In order to protect the information transmitted through the radio interface, either user data or signaling data, an advanced security scheme was conceived. Among the features of this scheme are: mutual authentication,key agreement, block ciphering, an integrity algorithm and a confidentiality algorithm. Keywords: Cellular Networks, 3G, UMTS, Security Architecture, AKA, KASUMI block ciphering algorithm, confidentiality and integrity algorithms.

1

Introduction

A cellular communication system is a special kind of wireless system whose features are the following: Frequency reuse: The whole coverage area isdivided into several smaller areas, called cells, in such a way that some transmission frequencies are used across a set of cells, and reused for another set of cells with little potential for interference. Mobility/Roaming: Subscribers are able to move freely around their home network and from this to another one. This feature requires that the network tracks the location of each subscriber in anaccurate way, in order to deliver calls and messages properly. Handoff/Handover: The subscriber transitions from one radio channel to another as he/she moves from one cell to another while engaged in a conversation. 1

Throughout the decades the need for ubiquitous communications has driven and encouraged the development, and subsequent deployment, of several technologies to provide users witheffective cellular communication means. Managers, executive officers and business people in general need to access their corporations’ information while traveling, consult information regarding the stock market, as well as call up their families and employees. For the rest of the people, cellular communications represents a great opportunity to keep in touch with each other by exchanging messages,engaging in voice sessions and transmitting data to/from the Internet; all through low-power mobile handsets. The third generation (3G) proposal for cellular communications claims to provide global roaming, high transfer rates and advanced services such as: commerce, global positioning system and multimedia messaging services via audio and video. All of these potential services, as well as the kind ofinformation transmitted throughout the network, make security issues more important to consider than before and security requirements even more stronger. This report provides deep information about the features of third generation proposals for cellular communications and the way security issues are addressed within these networks. The rest of the document is organized as follows: section 2...