Passing Hidden Information Using Attack Detectors

Electronic apparatus, comprising:

• a client device, which comprises:
• a client communication interface;
• a client processor, which is configured to store and process secret information;
• and
• an environmental detector, which is configured to detect a change in an operating environment of the client device;
• and
• a host device, which comprises:
• a host communication interface, which is configured to communicate with the client communication interface;
• a host processor;
• and
• an environmental signal generator, which is configured to generate changes within a predefined first range, relative to a baseline, in the operating environment of the client device,
• wherein the environmental detector is configured, in response to the detected change, to initiate a secure communication between the client processor and the host processor when the detected change, relative to the baseline, is in the first range, and to invoke a countermeasure against tampering with the client device when the detected change, relative to the baseline, is in a predefined second range, disjoint from the first range.

A method for communication, comprising:

• coupling a processor in a client device, which stores and processes secret information, to communicate with a host device via a communication interface;
• detecting a change, relative to a baseline, in an operating environment of the client device;
• and
• in response to the detected change:
• initiating a secure communication between the processor and the host device when the detected change is in a predefined first range;
• and
• invoking a countermeasure against tampering with the client device when the detected change is in a predefined second range, disjoint from the first range.