| 摘要 |
<p>A value transfer system of at least one VCD (=Value Carrying Device) (1) and at least one VAD (=Value Accepting Device) (2), the VAD (2) having a memory (53) for storing at least an aggregate value (28) of previous accepted values and means for transferring a claiming message (13), the VCD (1) having a memory (52) for storing at least a balance value (7) and means for transferring a proving message (14), wherein the VAD (2) includes into the claiming message (13) a transaction value (20), a previous aggregate value (21) and a corresponding previously computed proving cryptogram (22), the VCD (1) computes and includes into the electronic message (14) a transaction proving cryptogram (35), computed on the basis of the previous aggregate value (21), the corresponding previously computed proving cryptogram (22) and the transaction value (20), and the VCD (1) computes the at least one transaction proving cryptogram (35) only if it has established the correctness of the received previous aggregate value (21) by using said corresponding previously computed cryptogram (22) and after it has reduced the balance value (7) with the transaction value (20).</p> |
