cess consists of the following stages (as shown in Figure 6-14): 1. Cell Reselection: the MS may use neighbor BS information acquired from a decoded MOB_NBR- ADV message or may request to schedule scanning intervals or sleep intervals to scan neighbor Hashed Message Authentication Code (HMAC) is a method for calculating a message authentication code involving a cryptographic hash function in combination with a secret key. As with any message authentication code, this scheme may be used to simultaneously verify both the data integrity and the authenticity of a message. Any iterative cryptographic hash function may be used in the calculation of an HMAC. The cryptographic strength of the HMAC depends on the crypto- graphic strength of the underlying hash function, the size of its hash output length in bits, and on the size and quality of the cryptographic key. An iterative hash function breaks up a message into blocks of a fixed size and iterates over them with a compression function [20]. The definition of HMAC requires a cryptographic hash function, which we denote by H, and a secret key K. Let's assume H denotes a cryptographic hash function where data is hashed by iterating a basic compression function on blocks of data and B denotes the byte length of such blocks, e.g., B = 64, and L denotes the byte length of hash outputs, e.g., L = 16 or 20. The authentication key K can be of any length up to B, the block length of the hash function. Applications that use keys longer than B bytes will first hash the key using H, and then use the resulting L byte string as the actual key to HMAC. Let's define two fixed and different binary strings Sinner and Souter as follows: Sinner = 0 X 36 repeated B times and Souter = 0 X C repeated B times. To compute HMAC over the input data denoted as information, one should perform H(K + Souter, H (K + Sinner information)) where + denotes XOR operation [19]. "Cipher-based Message Authentication Code (CMAC) is a block cipher-based message authentication code algorithm.It is used to vali