中文摘要：

用于长数据分散存储的秘密共享协议面临着2方面问题，其一为长时安全性问题——份额在长期存储过程中可能渐次泄露，其二为份额分解与重构时的性能问题．已有秘密共享协议无法同时解决上述2个问题，鉴于此，选取Kurihara等的异或秘密共享（XORSS）协议和拜占庭协商协议为基础协议，设计了2个具有长时安全性的增强型异或秘密共享协议——用于份额更新的主动异或秘密共享（PXORSS）协议和用于门限提升的动态门限异或秘密共享（DTXORSS）协议．PXORSS协议和DTXORSS协议基于异或运算进行实现，延续了XORSS协议的高效性，此外给出了数学证明和过程分析，表明2协议满足长时安全性；设计了基于MapReduce模式的云存储原型系统，实验结果表明2协议性能较高、在长数据分散存储方面实用性较强．

英文摘要：

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 per- formance 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） proposed by Kurihara et al. and Byzantine Agreement Protocol as the underlying protocols, then designed protocol 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. PX- ORSS protocol and DTXORSS protocol are designed based on XOR operations, and both of the two protocols ex- tend 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 u- sing MapReduce paradigm illustrates that PXORSS protocol and DTXORSS protocol designed by this paper are high - performance and practical for decentralized storage of long - data.