Patent ID: 6366894
Filing Date: 2002-04-02
Classification: G06Q,G07F

Abstract:
A value transfer system comprising a multiplicity of electronic programmed microprocessor application carrier devices (ACD'S) each comprising an electronic purse having a value store, the ACD's being adapted to be coupled together in pairs so as to couple the purses and enable value to be exchanged in transactions between the purses, said value exchange being effected by exchanges of messages secured by a cryptographic security scheme, the system further comprising a sequential series of cryptographic security schemes ranging from old to new and each purse being programmed with at least two schemes in said series such that when two purses are coupled in a pair to exchange value between electronic purses, the oldest usable cryptographic security scheme common to both said two purses is identified and used and any cryptographic security scheme of the series in either said two purses which is older than the oldest common scheme is render unusable or, if there is no useable cryptographic security scheme common to both said two purses, the exchange of value is not permitted whereby for first and second purses having useable schemes A and B, where A is older than B, and a third purse having scheme B as its oldest usable scheme, the coupling of said first purse with said second purse results in scheme A being rendered unusable:1) in said first purse if said second purse is first coupled with said third purse and then coupled with said first purse before being coupled with any other purse, and 2) in said second purse if said first purse is first coupled with said third purse and then coupled with said first purse before being coupled with any other purse.