Importance

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Abstract

A data processing system, method and computer program provide for the secure updating an electronic purse which includes a list of purse records. The method includes the step of defining an authentication tree with an authentication tree function comprising a one way function of purse records in the list, the authentication tree having a first root for a first list of the purse records and storing the first root in a cryptographic facility. The authentication tree includes authentication MDC vectors, one for each purse record in the list. The method includes the step of receiving a transaction record in the cryptographic facility, including an authentication code, a cryptographic key, and an authentication MDC vector, for updating an existing purse record in the first list. The method then performs the step of performing a purse update function in the cryptographic facility. The method first authenticates the transaction record using the authentication code and cryptographic key and authenticates the existing purse record with the authentication MDC vector and first root. The method next performs the step of substituting an updated purse record for the existing purse record in the first list, forming a second list. The method then computes with the updated purse record and the first authentication MDC vector, a second path MDC vector and a second root of the authentication tree for the second list by computing a path MDC vector of the authentication tree between the updated purse record and the first root and stores the second root in the cryptographic facility.

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First Claim