ENCRYPTED COMMUNICATION SYSTEM WITH LIMITED NUMBER OF STORED ENCRYPTION KEY RETRIEVALS

A system for encrypted communication with external entities is configured to frustrate side channel attacks attempting to determine an encryption key. The system has a device with an encryption key stored in memory, an external entity with identity data for transmission to the device to initiate communication such that in response the device applies a one way function to the encryption key and the identity data to generate a variant key used to authenticate communications between the device and the external entity. The device is configured to limit the number of times the encryption key is allowed to be retrieved from the first memory to a pre-determined threshold.