Electrical computers and digital processing systems: support – Multiple computer communication using cryptography – Protection at a particular protocol layer
Reexamination Certificate
2005-12-27
2005-12-27
Smithers, Matthew (Department: 2137)
Electrical computers and digital processing systems: support
Multiple computer communication using cryptography
Protection at a particular protocol layer
C375S133000
Reexamination Certificate
active
06981157
ABSTRACT:
Master and slave Bluetooth-enabled devices communicate with other by sending messages using a carrier frequency that is constantly hopping from one frequency to another. In the prior art, each frequency in the sequence of frequencies, known as a hopping sequence, is determined as a known function of the master's Bluetooth address (BD_ADDR) and a universal time parameter. A computer-strong eavesdropper who is listening to one or more frequency bands over a period of time and within range of a user's piconet could determine the BD_ADDR of the user's device by comparing a detected hopping sequence with the hopping sequence associated with each possible BD_ADDR. Once the BD_ADDR of a user's device is determined, the user's location can thereafter be tracked as he moves from location to location using that device. To prevent this, the hopping sequence is determined as a known function of the master's BD_ADDR, a universal time parameter and a seed, which is a random or pseudo-random number communicated between the master to the slave and which is changed each time a new session begins on one of the user's devices operating on the piconet. The eavesdropper is then impeded from associating a detected pattern of channel usage with a particular master's BD_ADDR and its user.
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patent: 6366622 (2002-04-01), Brown et al.
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Jakobsson Bjorn Markus
Wetzel Susanne Gudrun
Gurey Stephen M.
Smithers Matthew
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