METHODS AND DEVICES FOR AUTHENTICATION AND KEY EXCHANGE

A device for securing protected content, and a method operational on such a device. The method comprises provisioning the first device with a cryptographic algorithm, generating a symmetric key also known to a second device, sending a first authentication challenge to the second device, the first authentication challenge based on the cryptographic algorithm and the symmetric key, receiving a second authentication challenge from the second device in response to sending the first authentication challenge, generating a first response to the second authentication challenge using a first response generation function, sending the first response to the second device, and receiving a second response to the first authentication challenge from the second device, the second response generated using a second response generation function, The first response generation function and the second response generation function generate different output values in response to one or more identical input authentication challenges.