Abstract: A method for enhancing data security when chip cards are used for payment transactions and input data are loaded into an algorithm when performing an authentication. The security of the debit and credit data is enhanced by subdividing the data blocks and by switching an additional feedback on and off following the downstream counters at preselected clock pulse times. The method is applicable to all authentication processes in conjunction with chip cards.

Abstract: A method and/or system is provided for generating pseudo-random sequences. The method and/or system may provide that the elements (&ggr;) of the pseudo-random sequences are discretely logarithmized.

Abstract: A system for the secure reading and processing of data on intelligent data carriers, such as chipcards, is described. Process executable in this system, in which the stored data and the authorizations or values associated with the data are especially well protected against access by unauthorized persons are also described. This is achieved by a useful combination of encryption processes. In particular, the risk involved with the spying out of master keys stored in autonomously operating terminals, such as vending machines or cardphones, is eliminated or at least reduced, thus counteracting the misuse of cash-reloadable chipcards increasingly used today.