Definitions Data-Origin authentication Data Integrity Early textbooks, viewed these two notions with no essential difference However, two very different notions Auth necessarily involves communications involves identifying the source of a message the most significantly, freshness of a message liveness of the message source message is fresh or not should be determined by apps 復大软件学院 LiTLiJT 10 Definitions • Data-Origin Authentication • Data Integrity – Early textbooks, viewed these two notions with no essential difference – However, two very different notions • Auth. necessarily involves communications • involves identifying the source of a message • the most significantly, freshness of a message; liveness of the message source. – message is fresh or not should be determined by apps