Abstract: Secret sharing protocols for decentralized storage of long-data face two problems.The first one is long term security threatening—shares may leak during the period of long-term storage.The second one is performance degrading when constructing shares and reconstructing secret.Traditional secret sharing shcemes cannot solve both of the two problems at the same time.For this reason,we chose XOR Secret Sharing(XORSS) protocol proposed by Kurihara et al.and Byzantine Agreement Protocol as the underlying protocols,then designed two long-term security enhanced XOR Secret Sharing protocols—Proactive XOR Secret Sharing(PXORSS) protocol for share updating and Dynamic Threshold XOR Secret Sharing (DTXORSS) protocol for threshold increasing.PXORSS protocol and DTXORSS protocol are designed based on XOR operations,and both of the two protocols extend the high-performance of XORSS protocol.Mathematical proof and procedure analysis show that the above two protocols can meet the requirement of long-term security;furthermore,prototyping cloud storage system using MapReduce paradigm illustrates that PXORSS protocol and DTXORSS protocol designed by this paper are high-performance and practical for decentralized storage of long-data.