US Patent 10298394 Method to authenticate two devices to establish a secure channel

The present invention relates to a method to authenticate two devices to establish a secure channel, one belonging to a first group of devices, the second belonging to a second group of devices, in a non-traceable manner without the need to share a secret, each group being authenticated by an authority that stores a group secret key into the devices under its authority. The method uses a set of authentication tokens, one for each of the other groups with which the device is intended to communicate, said authentication token comprising at least a random number and a cipher of at least this random number by the secret key of each of these other groups, said authentication tokens being further renewed at each communication with a device from another group.