Patent ID: 7552476
Filing Date: 2009-06-23
Classification: G06F,H04L

Abstract:
1. A method implemented in a computer system for providing security against the replay of a message transmitted from a first device to a second device over a network, comprising the steps of: the second device generating a first list of unique message enabling codes and storing the generated first list in a storage unit of the second device; a third device generating a second list of unique message enabling codes and storing generated second list in a storage unit of the third device; the first device requesting, from the third device, a unique message enabling code to be included in a message; the third device obtaining, in response to the request, a unique message enabling code from the second list stored in the storage unit of the third device and transmitting the obtained unique message enabling code to the first device; the first device generating a message to be transmitted to the second device, and transmitting the generated message to the second device together with the unique message enabling code transmitted from the third device; the second device receiving, via the network, the message, together with the unique message enabling code transmitted by the first device; the second device comparing the unique message enabling code received with the message from the first device with the first list of unique message enabling codes stored in the storage unit of the second device to determine whether the unique message enabling code received with the message is included in the stored first list; and the second device determining, based on the comparing step, whether or not to reject processing of the message by the second device, wherein, in a case where the comparing step determines that the unique message enabling code received with the message is included in the stored first list, processing of the message is not rejected, the message is processed, and the corresponding unique message enabling code is deleted from the stored first list, wherein, in a case where the comparing step determines that the unique message enabling code received with the message is not included in the stored first list, processing of the message is rejected, and wherein, in generating the first list and second list of unique message enabling codes by the second device and the third device, respectively, each of the second device and the third device independently generates its respective list of unique message enabling codes by using a common default value and a common hash key.