Abstract: A method of secure communication in which communication partners (A, B) in each case have a secret (S) and a public code (P), in which the communication partner (A) selects a random number (x) and the communication partner (B) selects a random number (y), in which a first partial code (Ax) is formed by the communication partner (A) and a second partial code (By) is formed by the communication partner (B) by using the public code (P) of the respective partner (B, A) and is transmitted to the respective other communication partner (B, A). A session code (gxy, gyx) is formed from the private random number (x, y), and the partial code (By, Ax) of the respective communication partner (B, A) while using the private secret code (S), the partial codes (Ax, By) and the session codes (gxy, gyx) being calculated in a fashion similar to the Diffie-Hellmann protocol.

Abstract: A data processing method where data to be processed is feed to a processing unit. Supplying a current to the processing unit for operating the processing unit and supplying in a randomly controlled manner a part of the current fed to the processing unit, to an auxiliary circuit.

Abstract: The copy protection system is a combination of a signature method and a coding or encryption method that uses a variable key. The data set is written only onto a predetermined device and it is released to a host for reading and deciphering only upon proper authorization. Copying of the encrypted data set is entirely useless, because the dataset is signed with a unique identification (e.g. the serial number) of the device.