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Unformatted text preview: Confidentiality in the UMTS Radio Access Network Simulation approach under OPNET Said El Hajji and Ghizlane Orhanou Laboratoire Math´ematiques, Informatiques et Applications, Universit´e Mohammed V Agdal, Facult´e des Sciences BP 1014, Rabat, Maroc [email protected] and [email protected] Abstract The Universal Mobile Telecommunications System (UMTS) offers a panoply of 3G services. In addition to delivery of images, graphics and video communications, UMTS is used for such applications as banking and e-commerce and hence security is a critical concern. In the present paper, we are interested in the confidentiality feature in the UMTS Network Access. Ciphering when applied is performed in the RNC and the UE either in the RLC sub-layer or in the MAC sub-layer. Our current research aims to examine exactly where the encryption/decryption occurs in the protocol stack of an UMTS network. And then introduce this security feature in the OPNET Modeler which is used to give a simulation approach of the use of the UTRAN confidentiality feature between RNC and UE. This paper is organized as follows. First, a brief description of the UMTS confidentiality mechanism. Then, We will be interested in the UMTS stack layers where the ciphering and deciphering of data would be performed. After, we will describe our simulation approach by exposing the changes made to mobile station and RNC node models in order to implement the confidentiality feature. Keywords: UMTS, Confidentiality, Encryption, f8, RLC Acknowledged Mode, RLC Unacknowledged Mode, RLC Transparent Mode, OPNET simulation 1. CONFIDENTIALITY FEATURE IN THE UMTS RADIO ACCESS NETWORK 1.1. Confidentiality User data and some signalling data are considered sensitive and their confidentiality should be protected over the radio access link. To ensure this data confidentiality on the air interface, the following features are provided : • Cipher algorithm (f8) agreement: nowadays, there exist two variants of the cipher algorithm: UEA1 based on KASUMI algorithm and UEA2 based on SNOW 3G algorithm [1, 2]. The MS ( Mobile Station ) and the SN ( Serving Network ) can securely negotiate the algorithm to use in their mutual communication. • Cipher key (CK) agreement: the agreement on a cipher key to use subsequently is done between the MS and SN during the Authentication and Key Agreement procedure ; • Confidentiality of user and signaling data: this property insures that the user and signalling data cannot be overheard on the radio access interface; 1 Confidentiality in UMTS Radio Access Network - Simulation approach under OPNET 1.2. UMTS Encryption function f8 The data confidentiality during its transmission over the radio interface is fulfilled by an UMTS confidentiality cryptographic function f8  which is a symmetric synchronous stream cipher. This type of ciphering has the advantage to generate the mask of data before even receiving the data to encrypt, which help to save time. Furthermore, it is based on bitwise operations which areto encrypt, which help to save time....
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This note was uploaded on 02/04/2012 for the course COMPUTER 101 taught by Professor Ahmed during the Spring '11 term at alamo.edu.
- Spring '11