| 摘要 |
The present invention strengthens authentication protocols by making it more difficult for handset impersonators to gain system access using replay attacks. This goal is accomplished using challenge codes as a parameter for determining au thentication codes, whereby different challenge codes cause different authentication code s to be generated. In one embodiment, the challenge codes are functions of challenge types (e.g., global or unique challenges) and/or handset states (e.g., call origination, page response, registration, idle, and SSD-A update). This embodiment prevents handset impe rsonators from successfully utilizing replay attacks to impersonate a legitimate hands et if the legitimate handset is in a different state than the handset impersonator, or if the legitimate handset is responding to a different challenge type than the handset imperso nator.
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