Patent ID: 7990930

Claim:
A method for operating during an authentication in an AT (Access Terminal) having a Removable User Identity Module (R-UIM) card using a Cellular Authentication Voice Encryption (CAVE) algorithm, comprising the steps of: extracting, by the AT, a RANDom number (RAND) from a CHAP (Challenge Handshake Authentication Protocol) challenge message from a High Rate Packet Data (HRPD) system; instructing, by the AT, the R-UIM card to use the CAVE algorithm to calculate an authentication parameter using the RAND; and transmitting, by the AT, to the HRPD system, the authentication parameter and an identification of the AT in a CHAP response message, in response to the CHAP challenge message, wherein the R-UIM card is used for authenticating the AT in Code Division Multiple Access (CDMA) 2000 1x and HPRD systems, and wherein the AT is a dual-mode access terminal capable of accessing both the CDMA 2000 1x and HPRD systems for packet data services.