Patent ID: 8694856

Claim:
A system for generating an identifying response pattern comprising a memory used as a physically unclonable function comprising a plurality of re-writable memory locations each memory location having at least two possible logical states, and an input for receiving an activation signal so as to cause each of said memory locations to enter one of its possible logical states, the entered state being dependent on physical, at least partially random characteristics of said memory, and thereby generating a response pattern of logical states useful for identifying the system, the generation of the response pattern is sensitive to degradation after repeated applications of the activation signal, a memory-overwriting device configured for overwriting at least a first portion of the plurality of memory locations to obscure the response pattern in the memory, and an anti-degradation device configured to write to each respective location of a second portion of the plurality of memory locations an inverse of a logical state previously read from the respective location of the second portion.