Abstract: In practical application,the ownership of multi-owner RFID tags transfers due to changes not only in owners of the tags,but also in the proportion of weights possessed by each owner.Therefore,in this paper,a tag ownership protocol for multi-owner internal weight changes with trusted third parties (TTP) was put forward to resolve this problem.As there is a trusted third party involved in the conversion of ownership,the original owner completely transfers the tag’s ownership to the new owner after the weight changes,which means original owners in the protocol are irrelevant.Lagrange interpolating polynomial and Shamir’s threshold secret sharing scheme are used in the protocol,and security analysis is conducted with GNY logic.The results show that the protocol can resist all kinds of attacks in the process of conversion.Meanwhile,the results of simulation experiments indicate the time consumption of tags and the amount of calculation fall within an acceptable range.

Key words: GNY logic, Independence of old owner, Lagrange, Ownership transfer, Secret sharing, Trusted third party