SYNCHRONOUS SMART CARD AUTHENTICATION AND ENCRYPTION CIRCUIT AND METHOD

摘要

Encryption circuits and methods, in particular for smart cards, are disclosed. Smart cards without microprocessors may be authenticated very simply by using encryption with a secret card data table on which recursive cycles are executed. During each cycle, a word is read out of the table, said word being at an address that is at least partially defined by the word read out in the previous cycle. The new address preferably consists of several bits from the previous word and a bit from internal card data, external data supplied by a card reader, or a register containing a partial encryption result.