Patent ID: 7281134
Filing Date: 2007-10-09
Classification: H04L

Abstract:
1. In a security system comprising a control panel and a plurality of security devices interconnected to the control panel over a communications medium located in a premises, a method of authenticating a security device to determine if it is authorized to be used with the security system, the method comprising the steps of: a. storing a first encryption key and a second encryption key in the control panel; b. storing the first encryption key and the second encryption key in the security device; c. generating a challenge index at the control panel; d. producing a challenge message by encrypting the challenge index using the first encryption key at the control panel and including the encrypted challenge index in the challenge message; e. transmitting the challenge message over the communications medium to the security device; f. receiving at the security device the challenge message over the communications medium from the control panel; g. extracting the encrypted challenge index from the challenge message; h. decrypting the encrypted challenge index using the first encryption key at the security device to produce a response index; i. producing a response message by encrypting the response index using the second encryption key at the security device and including the encrypted response index in the response message; j. transmitting the response message over the communications medium to the control panel; k. receiving at the control panel the response message over the communications medium from the security device; l. extracting the encrypted response index from the response message; m. decrypting the encrypted response index using the second encryption key at the control panel to produce the response index; n. comparing the response index decrypted by the control panel with the challenge index generated by the control panel;