This describes the perimeter detect feature on Zymkey 4i.
Perimeter Detect provides two additional layers of physical security that can be used to detect when the perimeter of your device is breached. This is an important feature when devices are deployed in the field, unattended or in high risk environments.
Zymkey 4i includes two independent Perimeter Loops that can be configured to meet different applications.
When a Perimeter Loop is breached, Zymkey 4i can be configured (at time of binding) to respond with different “Actions”, depending upon your security policy.
Connecting Perimeter Loop Circuits
Zymkey 4i uses a standard microUSB connector to interface to perimeter circuits 1 and 2. This is convenient for rapid prototyping and small scale production situations.
(For high volume applications, different connector types are available. Contact Zymbit for more details.)
Using a Standard USB EXTENSION Cable for Perimeter Loop
You can use a micro-usb EXTENSION cable, which carries all necessary signals, to connect to the perimeter detect. Here is one example of an extension cable that will work. (Remove the female connector to expose the flying leads as shown below, then connect your perimeter circuits - P1, P2 - to these)
IMPORTANT: do NOT use standard micro-usb charging cable it will not work, because it does not have a wire on pin 4.
Each perimeter loop should be connected with a 30 AWG wire or thicker and nominal length of 2 feet. For longer lengths contact Zymbit. The wire should be electrically insulated for all applications. A shielded cable may be necessary for electrically noisy or industrial applications.
Custom flex PCBs and rigid PCBs may also be used to complete a perimeter loop circuit.
Perimeter Breach Response Actions
Prior to permanently binding your Zymkey to a specific host device, it can be configured through the API to respond to a perimeter breach event in one of three ways. After permanent binding is completed, the selected configuration is locked and immutable.
A) Do nothing (disable)
B) Notify host when perimeter breach occurs
C) Destroy all key material (this essentially destroys any encrypted data or file system)
Refer to API documentation for more details.