I am looking for an authentication device with SHA. After some research I found an application note (http://www.atmel.com/Images/doc8...) from Atmel where they were talking about the AT88SA100S, the AT88SA10HS, and the AT88SA102S. I like the concept with the secret (64 fuse bits) and the key which both are used to calculate a response after a challenge was received. This solves the problem, that a supplier does need the whole secret key when programming the device. But unfortunately these three devices have only a 1-Wire interface for communication. Is there an alternative product from Atmel with an I2C communication interface which is working with the same secret/key concept?