Method for diversifying a basic key and for authenticating a key thus diversified as having been derived from a predetermined basic key, and system for implementation

摘要

The subject of the invention is a method for diversifying a basic key and for authenticating a key thus diversified as having been derived from a predetermined basic key, and system for implementation. Before putting a portable object 2 into use, an accredited body calculates a secret key Sd on the basis of a unique basic key Sb and records it in the DOM memory of the object 2. Each object 2 has a different secret key. In use, the object 2 is coupled to an apparatus 3 providing a service, the control device 4 of which recalculates a secret key Sd on the basis of a basic key Sb and verifies that this key is identical to that recorded in the object 2. The invention applies especially to diversification of secret keys recorded in standardised credit cards. IMAGE