| 摘要 |
<p>The goal of the present invention is to secure a prepaid device for access to audio/video content having the possibility of reimbursement of the unused balance upon presentation of the aforementioned device to a control center. This goal is achieved by a method for managing a debit value (V1) in a prepaid device and comprising an identifier (UA) unique to each device and a control value (CT), this method comprising the following steps: -receiving of a request to modify the debit value (V1 ) by an amount (M), -calculating a new debit value (V1') after the modification of the debit value (V1) by the amount (M), - determining a positive whole number or zero of steps (N) according to a function expressing the modification of the new debit value (V1') relative to the debit value (V1), - if the number of steps (N) is non-zero, modifying the control value (CT) by executing at least one one-way function on said control value (CT) a number of times equal to the number of steps (N).</p> |
