Abstract: A system and a method for cryptographic reduced-coupon reloading are provided, where a coupon includes a pseudo-random number ri=PRFK(i), where i is an index for labeling the coupon, PRF is a predetermined pseudo-random function and K is a regeneration key, and a “reduced-coupon” xi=ƒ(ri), where ƒ is a predetermined one-way function, where: a candidate device and a second device acquire a common value of a token T, the candidate device transmits a verification value vT to the second device, the second device verifies whether the verification value is equal to PRF?Q(T), where PRF? is a predetermined keyed pseudo-random function identical to, or derived from, the pseudo-random function PRF, where Q is an authentication key owned by the second device and known to the candidate device provided the candidate device is a legitimate reloading device, and if the verification is positive, one or several reduced-coupon(s) provided by the candidate device are stored in the second device.

Abstract: A system and a method for cryptographic coupon reloading are provided for, wherein a coupon comprises, on one hand, a pseudo-random number ri=PRFK(i), where i is an index for labeling the coupon, PRF is a predetermined pseudo-random function and K is a regeneration key, and, on the other hand, a “reduced-coupon” xi such that xi=ƒ(ri), where ƒ is a predetermined one-way function, characterized in that it comprises the following steps: a candidate device (1) and a second device (2) acquire a common value of a token T, said candidate device (1) transmits a verification value vT to the second device (2), the second device (2) verifies whether said verification value vT is given by vT=PRF?Q(T), where PRF? is a predetermined keyed pseudo-random function identical to, or derived from, said pseudo-random function PRF, and where Q is an authentication key owned by the second device (2) and known to the candidate device (1) provided the candidate device (1) is a legitimate reloading device (1), and if the verificati