Abstract: Smart card payment process.The card in particular contains an irreversible counter, a balance and a certificate proving the integrity of the preceding informations. The content of the card can only be updated by terminals knowing, the calculation secrets of the certificate. By means of the irreversible counter which intervenes in the calculation of the certificate, it is not possible to reload into the card a prior content (balance/certificate), because such a reloading requires the incrementation of the counter, which renders null and void the prior certificate.

Abstract: The installation comprises a remote loading mode in which in response to a remote loading request word (R) for a predetermined number of value units emanating from the autonomous set (PA), there is provided:an active authentication of the autonomous set (PA) and of the access system (SAA);a calculation of a remote loading passkey (KCH or (SCH, PCH)) at the level of the authorization center (CA);a transmission of the enciphered remote loading passkey destined for the access system (SAA);a secure remote loading of the prepayment means (MPAY) originating from the access system with the aid of the remote loading passkey thus transmitted.

Abstract: In the course of the intercommunication between the base station and the autonomous telephone set, the first means of authentication initially generates a keyword dependent on the call charge for the current service and transmits it to the autonomous telephone set. The second means of authentication then calculates the transform of the keyword by the encryption function F with the aid of the subscriber's secret key, and transmits the transform to the first means of authentication which finally checks the authenticity of the transform to totally block the intercommunication if the authenticity is not confirmed by the check.

Abstract: The disclosure concerns memory cards and, more particularly, cards that are used as means of prepayment in installations for the dispensing of products and services. It is proposed to make the memory rechargeable by means of a credit counter, incrementable from outside the card, and a comparator which compares the content of this counter with that of a page counter. The page counter records the number of pages of P accounting units already used up. A no more credit signal is emitted on an external terminal when the content of the page counter reaches the content of the credit counter. A security system against the fraudulent recharging of the card is set up by an algorithm bringing into play the content of the credit counter and an identification number contained in the card.