Authentication system wherein definition signals of two devices are

Abstract

An authentication system having a first device and a second device between which signals may be communicated. The first device includes a first memory for storing a definition signal and the first device generates a first signal to be communicated to the second device. The first device also generates a first alteration signal, and introduces an alteration into a first section of the definition signal stored in the first memory in accordance with the first alteration signal. The second device includes a second memory for storing the definition signal, and generates, in response to a receipt of the first signal, a second signal to be communicated to the first device. The second signal includes a second section of the definition signal stored in the second memory, and the second device also generates a second alteration signal and introduces an alteration into a third section of the definition signal stored in the second memory in accordance with the second alteration signal. In addition, the first device compares the second section of the definition signal in the second signal originating from the second device with a corresponding section of the definition signal stored in the first memory, and introduces the alteration into the first section of the definition signal stored in the first memory in accordance with a comparison result. The first and third sections, moreover, are corresponding sections of the definition signals stored in the first and second memories, respectively.