a fast data transfer collection system using message authentication and contactless rf proximity card technology in non - contact storage and retrieval applications . the system is generally comprised of host computers , target radio frequency terminals , and a plurality of portable tags . a host provides specific application functionality to a tag holder , with a high degree of protection from fraudulent use . a target provides control of the rf antenna and resolves collisions between multiple tags in the rf field . a tag provides reliable , high speed , and well authenticated secure exchanges of data / information with the host resulting from the use of a custom asic design incorporating unique analog and digital circuits , nonvolatile memory , and state logic . each tag engages in a transaction with the target in which a sequence of message exchanges allow data to be read from the tag . these exchanges establish the rf communication link , resolve communication collisions with other tags , authenticate both parties in the transaction , rapidly and robustly relay information through the link , and ensure the integrity and incorruptibility of the transaction . the system architecture provides capabilities to ensure the integrity of the data transferred thus eliminating the major problem of corrupting data on the card and in the system . the architecture and protocol are designed to allow simple and efficient integration of the transaction product system into data / information processing installations .