Patent ID: 8315391
Filing Date: 2012-11-20
Classification: H04L

Abstract:
1. An information access system for accessing information stored in a contactless information storage device, the information access system comprising: a reader/writer device that is connectable to an information processing apparatus, and comprises: a first memory, a first control unit, a first encryption unit that encrypts request data that comprises an information request to generate encrypted data, a first transmitter unit that transmits an information request signal at a first frequency in transmission time periods in a transmission cycle that carries the encrypted data, a first receiver unit configured to be continuously ready to receive an RF signal at a second frequency different from the first frequency, and a first decryption unit that decrypts other encrypted data carried by an RF signal at the second frequency; and an active-type contactless information storage device that comprises: a second memory, a second control unit, a second receiver unit that senses a carrier of an RF signal at the first frequency for detection, a second decryption unit that decrypts encrypted data carried by the information request signal at the first frequency to reproduce the request data, a second encryption unit that encrypts, in response to the information request in the reproduced request data, response data that comprises an identification stored in the second memory to generate response encrypted data, and a second transmitter unit that transmits a response signal at the second frequency that carries the response encrypted data, wherein in response to a request from the information processing apparatus, and under the control of the first control unit, the first encryption unit, encrypts, using a first encryption key stored in the first memory, first data that comprises the information request and a second encryption key to generate first encrypted data and encrypts second data that comprises the information request, using the second encryption key stored in the first memory, to generate second encrypted data, and the first transmitter unit transmits the information request signal at the first frequency that carries alternately in successive time slots the first encrypted data and the second encrypted data, and under the control of the second control unit, the second receiver unit senses a carrier of an RF signal at the first frequency in carrier sensing periods that occur in a carrier sensing cycle, wherein when the second receiver unit senses and detects a carrier of an RF signal at the first frequency in one of the carrier sensing periods, under the control of the second control unit, the second receiver unit further receives the information request signal at the first frequency, and the second decryption unit decrypts, using an active encryption key stored in the second memory, the encrypted data carried by the information request signal at the first frequency to reproduce the data, wherein the active encryption key stored in the second memory is the first or second encryption key, and in response to the information request in the data reproduced by the second decryption unit, the second encryption unit encrypts the response data using the active encryption key stored in the second memory to generate the response encrypted data, and the second transmitter unit transmits the response signal at the second frequency that carries the response encrypted data, wherein the first receiver unit receives the response signal at the second frequency, the first decryption unit decrypts the response encrypted data carried by the response signal at the second frequency, using the corresponding first or second encryption key stored in the first memory to reproduce the response data, and when the second encryption key different from the active encryption key stored in the second memory is in the data reproduced by the second decryption unit, the second control unit sets the second encryption key as the active encryption key to be stored in the second memory.