An external key device including a test access port connector adapted to mate with a test access port, a test equipment connector adapted to communicatively couple to test equipment, and an external encryption chip adapted to communicate signals through the test access port to an internal encryption chip. The internal encryption chip at least one of decrypts at least one test data input from the external encryption chip based on a password shared by the external encryption chip and the internal encryption chip and encrypts at least one test data output from a protected device. The external encryption chip at least one of decrypts at least one test data output from the protected device based on the shared password and encrypts at least one test data input generated by the test equipment.