Proximity check for communication devices

A reader device configured for contactless communication with a transponder device, the reader device comprising:

• an antenna;
• a memory;
• and
• a processing unit,
• wherein the processing unit is configured to:
• transmit a command to the transponder device, the command including a request for a plurality of measured response times for a number n of previous command-response exchanges stored in the transponder device;
• in response to the command, receive from the transponder device, a response including the plurality of measured response times for the number n of previous command-response exchanges stored in the transponder device;
• and
• determine whether a predetermined criterion for the proximity check is fulfilled by comparing the plurality of measured response times stored in the reader device with the plurality of measured response times transmitted by the transponder device in the response.

A transponder device configured for contactless communication with a reader device, the transponder device comprising:

• an antenna;
• a transponder memory;
• and
• a processing unit,
• wherein the processing unit is adapted to:
• measure and store in the transponder memory a measured response time during each command-response exchange of a plurality of command-response exchanges with the reader device;
• receive a command from the reader device, the command including a request for a plurality of measured response times for a number n of previous command-response exchanges stored in the transponder memory;
• and
• in response to the command, send a response including the plurality of stored measured response times for the previous n command-response exchanges.

A method performed by a transponder device and a reader device, the method comprising:

• conducting a number n of command-response exchanges between the reader device and the transponder device;
• in conjunction with conducting the number n of the command response exchanges, storing, within the transponder device, a plurality of measured response times;
• and
• after conducting the number n of command-response exchanges, performing a proximity check to determine whether the transponder device is in proximity of the reader device by
• transmitting a command from the reader device to the transponder device, the command including a request for the plurality of measured response times stored within the transponder device,
• in response to receiving the command at the transponder device, the transponder device transmitting a response to the reader device, the response including the plurality of measured response times stored within the transponder device, and
• determining whether a predetermined criterion for the proximity check is fulfilled by comparing a corresponding plurality of measured response times stored within a memory accessible to the reader device with the plurality of measured response times transmitted by the transponder device in the response.