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Cryptographic key exchange over an electrostatic channel

  • US 9,763,087 B2
  • Filed: 07/14/2014
  • Issued: 09/12/2017
  • Est. Priority Date: 07/14/2014
  • Status: Active Grant
First Claim
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1. An interactive display device comprising:

  • a touch sensor including an electrode matrix having row electrodes and column electrodes, where the interactive display device is configured to excite one or more electrodes of the electrode matrix according to a repeated touch-sensing frame performed repeatedly to sense touch input to the touch sensor, the repeated touch-sensing frame being divided into a plurality of different portions each comprising one or more time slots, the plurality of different portions including a drive portion, a sensing portion, and an information sending portion, wherein the one or more electrodes form a capacitive coupling with an electrode tip of an input device, where the touch sensor uses the capacitive coupling between the electrode tip and the one or more electrodes of the electrode matrix to determine a position of the electrode tip relative to the electrode matrix during the sensing portion of the repeated touch-sensing frame, and where the interactive display device uses the capacitive coupling between the electrode tip and the one or more electrodes of the electrode matrix to capacitively send a cryptographic key via an electrostatic channel to the input device during the information sending portion of the repeated touch sensing frame; and

    a radio transceiver configured to communicate via a radio channel, where the interactive display device is configured to subsequently exchange encrypted communications over the radio channel, the encrypted communications being encrypted using the cryptographic key.

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