Abstract: The invention relates to a method and a device for protecting software delivered to a user by a supplier. The method amounts to rendering the programs non-executable in the state in which they have been delivered to the users. With each program (P.sub.i) there is associated a validation key defined via a main validation key (V.sub.i) delivered by the supplier and recorded in a storage area (M) of the user's machine (1), and via a supplementary key (V'.sub.i) computed on the lever of a card (C) issued to the user via a secret code (S) and via arguments (b.sub.i) that identify each program (P.sub.i) and are recorded in a storage area (M1) of the card (C).

Abstract: The object of the invention is a process for certifying the origin of at least one item of information stored in the memory of a first electronic device such as a portable card and transmitted to a second electronic device such as a portable card, and a system for implementing said process. An individual A controls a card C.sub.A which has a memory M.sub.A that contains an item of information I.sub.A specific to the individual A. An individual B controls a card C.sub.B which has a memory M.sub.B that contains an item of information I.sub.B specific to individual B. In order for individual B, who receives the information I.sub.A, to be certain of the origin of this information I.sub.A, each of the two cards C.sub.A and C.sub.B calculates a result R related to the information I.sub.A, to a secret set (S) shared by the two cards, to a random number (E.sub.B) supplied by individual B, and to a parameter J which, in turn, is related to the two items of information (I.sub.A, I.sub.

Abstract: Each card of a set of credit cards includes a memory having plural memory fields. The memory of each card in a set includes a first unalterable multi-bit field indicative of an identification of an external means with which the card can be used, as well as a second unalterable mutli-bit field indicative of operations that can be performed with the card on the external means and an alterable multi-bit field indicative of the number of credit units available to a card holder. Each card includes circuits for controlling the memory, and means for temporarily coupling the memory and circuits to the external means. Each of the first and second unalterable bit fields includes n bits. A change from one bit state to the other bit state of a predetermined number, m, of bits in the unalterable fields of each card in the set is irreversible after imprinting, where m is equal to or less than n.

Abstract: A credit card system includes a credit card containing a memory for storing coded information indicative of: an identification of the use for which the article is intended, an identification of units used to keep account of operations which are performed in connection with the credit card, and the number of units available to a holder of the credit card. The memory is structured so that the two identification data zones have bits wherein a change from one binary value to another is irreversible, to prevent tampering of the identification of the card. The card also includes circuits for controlling the memory and contacts for temporarily coupling the card to an imprinting and/or operating means that are respectively coupled to the card at the time it is purchased and when it is being used to purchase goods or services. When the card is purchased, the number of units is imprinted onto the card in the third zone, and the number of these units is decremented as the card is being used.