universally composable group key exchange protocol

该文提出了一个通用可组合框架下的组密钥交换理想函数,并在防篡改硬件令牌的基础上,利用部分隔离状态下证据不可区分知识证明,设计了一个组密钥交换协议,安全地实现了这个理想函数.和采用CRS模型的协议相比,降低了把整个信任集中于一处带来的风险.提出的组密钥交换协议经过证明具有AKE安全,并且能够抵抗适应性敌手攻击和恶意参与者攻击

forward-backward secure group signature scheme

为了研究群签名方案的前向安全性和后向安全性保证技术,基于哈希链实现了一种具备前向安全和后向安全的群签名方案,在密钥更新阶段采用门限方法与其他成员 共享其每个时间周期内的子秘密,在签名生成阶段成员利用公开信息和哈希函数单向性验证其他参与者份额的真实性,即使在验证失败的情况下也可由多个参与者利 用门限方案合作完成群签名,提升了系统的安全性和稳定性.分析表明,该方案比现有同类群签名方案具有更好的安全性和更高的效率.To investigate forward security and backward security,a one-way Hash chain-based group signature scheme is presented,in which the subsecrets of each interval are shared by using threshold method,and the validity of shares can be verified by using Hash chains and public information.The group signature can be generated successfully even if minority players present fault shares to the signer by utilizing the threshold method.In this way,the performance and security are improved.Analysis shows that the proposed scheme is not only more efficient but also more secure than previous group signature schemes

一种高效的基于身份的可验证加密签名方案

基于Shim数字签名方案,提出了一种基于身份的可验证加密签名方案.该方案不需要零知识证明系统提供验证,避免了因复杂交互而产生的计算负担.该方案的可验证加密签名仅需在普通签名参数上作一次加法运算即可完成,可验证加密签名的验证仅需在普通签名验证等式右边作一次乘法运算即可实现,方案形式较为简洁.在CDH问题难解的假设下,该方案在随机预言模型中是可证明安全的.分析表明,与现有同类方案相比,该方案具有更少通信量和更低的计算复杂度.Verifiably encrypted signature is useful in handling the fair exchange problem, especially online contract signing. A new ID-based verifiably encrypted signature scheme is proposed based on Shim signature scheme. The new scheme does not use any zero-knowledge proofs to provide verifiability, thus eliminates some computation burden from complicated interaction. The creation of verifiably encrypted signature in the scheme is realized by adding a value into one parameter of Shim signature. The verification of verifiably encrypted signature in the scheme is implemented by multiplying one pairing value with the right part of verification equation in Shim signature. Taking account of above reasons, the design of the proposed scheme is compact. The new scheme is provably secure in the random oracle model under the CDH problem assumption. The analysis results show that the presented scheme needs smaller communication requirements and its computation complexity is more optimized compared with the previous ID-based verifiably encrypted signature schemes. ID-based public key cryptography has become a good alternative for certificate based public key setting, especially when efficient key management and moderate security are required. Our new verifiably encrypted signature scheme is an entirely ID-based scheme, which provides an efficient primitive for building fair exchange protocols in ID-based public key cryptosystem

novel fair exchange protocol based on concurrent signature

基于完美的并发签名,提出了一个新颖的公平交易协议,在双方起初交换2个模糊签名及相关交易数据的时候,任何人都无法辨认是谁签了哪一个签名,直到发起方公布一个秘密信息,2个签名才同时绑定到各自的签署方,之后另一方发送解密商品的密钥,从而让双方都能公平的得到对方的物品,而且本协议无需可信第三方(TTP)的参与即可让交易双方公平地交易数据条目,避免了两方勾结的可能性以及可信第三方参与协议的瓶颈.通过分析,协议很好地保证了公平性、不可否认性以及不可滥用性等性质,而且协议只需两方发送4条消息,简洁高效

dynamic multi-secret sharing scheme based on cellular automata

针对现有基于细胞自动机多秘密共享方案存在安全性较低和可扩展性较差的问题,提出了一种可验证的动态门限多秘密共享方案.方案中参与者的子秘密可以在多次秘密共享过程中重复使用,减少了秘密分发者的计算负担;在不改变现有参与者子秘密的前提下,可动态加入新参与者和新共享秘密;在秘密分发和重构过程中,能够实现参与者对秘密分发者以及秘密重构者对参与者的验证,及时检测和识别分发者对参与者以及参与者对重构者的欺骗,提高了重构秘密的成功率以及方案的安全性.国家“九七三”重点基础研究发展计划基金项目(2007CB311203)|国家科技重大专项基金项目(2009ZX03004-003-03)|国家自然科学基金项目(60970135,61170282,61003285)|重庆市教育委员会科学技术研究项目(KJ120504)|重庆邮电大学博士启动基金项目(A2011-52)In order to solve the problem that the previous cellular automata based multi-secret sharing schemes are unsecure and inflexible, a verifiable dynamic multi-secret sharing scheme is presented in this paper. In the proposed scheme, the shares of participants can be reused so that the computation cost of the dealer is reduced. New participants or new secrets can be added into the system without updating the shares of original participants. Cheating of dealer and participant can be detected and identified during the process of distributing the shares and reconstructing the secret. These features contribute to improve the success probability of constructing secret and security

气候变化国家评估报告(Ⅱ):气候变化的影响与适应

已经观测到的气候变化影响是显著的、多方面的。各个领域和地区都存在有利和不利影响,但以不利影响为主,未来的气候变暖将会对中国的生态系统、农业以及水资源等部门和沿海地区产生重大的不利影响。采取适应措施可以减轻气候变化的不利影响,应将适应气候变化的行动逐步纳入国民经济和社会发展的中长期规划中。由于我国科学研究的相对不足和科学认识能力的局限,目前的气候变化影响评估方法和结果还存在很大的不确定性。应当加强区域适应气候变化的案例研究、扩大研究领域、加强极端天气、气候事件影响的研究,以降低影响评估的不确定性,并提出切实可行的适应对策

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel