THRESHOLD PROXY RE-SIGNATURE

The focus of this paper is to design an efficient and secure solution addressing the semi trusted issue in proxy re-signature schemes, i.e., the proxy knows the re-signature key from user A to user B, so he is able to translate any signatures made by user A to user B, which damages the essential requirement （＂non-repudiation＂ property） of proxy re-signature schemes. In this paper, the authors first define the security model for threshold proxy re-signature scheme, and then propose two threshold proxy re-signature schemes based on Ateniese-Hohenberger＇s and Shao-Cao-Wang-Liang＇s approach.

Unidirectional Identity-Based Proxy Re-Signature with Key Insulation in EHR Sharing System

The introduction of the electronic medical record(EHR)sharing system has made a great contribution to the management and sharing of healthcare data.Considering referral treatment for patients,the original signature needs to be converted into a re-signature that can be verified by the new organization.Proxy re-signature(PRS)can be applied to this scenario so that authenticity and nonrepudiation can still be insured for data.Unfortunately,the existing PRS schemes cannot realize forward and backward security.Therefore,this paper proposes the first PRS scheme that can provide key-insulated property,which can guarantee both the forward and backward security of the key.Although the leakage of the private key occurs at a certain moment,the forward and backward key will not be attacked.Thus,the purpose of key insulation is implemented.What’s more,it can update different corresponding private keys in infinite time periods without changing the identity information of the user as the public key.Besides,the unforgeability of our scheme is proved based on the extended Computational Diffie-Hellman assumption in the random oracle model.Finally,the experimental simulation demonstrates that our scheme is feasible and in possession of promising properties.

IMPROVEMENT OF NONREPUDIABLE THRESHOLD MULTI-PROXY THRESHOLD MULTI-SIGNATURE SCHEME WITH SHARED VERIFICATION

In 2005, Bao, et al. [Appl. Math. and Comput., vol.169, No.2, 2005] showed that Tzeng, et al.’s nonrepudiable threshold multi-proxy multi-signature scheme with shared verification was insecure, and proposed an improved scheme with no Share Distribution Center (SDC). This paper shows that Bao, et al.’s scheme suffers from the proxy relationship inversion attack and forgery attack, and pro- poses an improvement of Bao, et al.’s scheme.

SECURITY ANALYSIS AND IMPROVEMENT OF A NEW THRESHOLD MULTI-PROXY MULTI-SIGNATURE SCHEME

Kang, et al. [Journal of Electronics(China), 23(2006)4] proposed a threshold multi-proxy multi-signature scheme, and claimed the scheme satisfies the security requirements of threshold multi-proxy multi-signature. However, in this paper, two forgery attacks are proposed to show that their schemes have serious security flaws. To overcome theses flaws, an improvement on Kang, et al.’s scheme is proposed.

Multi-proxy quantum group signature scheme with threshold shared verification

A multi-proxy quantum group signature scheme with threshold shared verification is proposed. An original signer may authorize a proxy group as his proxy agent. Then only the cooperation of all the signers in the proxy group can generate the proxy signature on behalf of the original signer. In the scheme, any t or more of n receivers can verify the message and any t - 1 or fewer receivers cannot verify the validity of the proxy signature.

Proxy Multisignature Scheme with (t,m) Threshold Shared Verification

A proxy multisignature scheme with （t, m） threshold shared verification is first proposed based on elliptic curve. In proposed scheme, a proxy signer can sign a message on behalf of n original signers for specific group of verifiers and only any t or more verifiers together in the specific group of verifiers are able to verify the validity of the proxy multisignature on behalf of the group of specific verifiers, but t-1 or fewer verifiers can not. Since the proposed scheme is constructed based on elliptic curve, it requires smaller bandwidth and achieves more secrecy of data transmission; it is more etffcient for signature and verification etc.

Improvement of Identity-Based Threshold Proxy Signature Scheme with Known Signers

In 2006, Bao et al proposed an identlty-based threshold proxy signature scheme with known signers. In this paper, we show that Bao et al＇s scheme is vulnerable to the forgery attack. An adversary can forge a valid threshold proxy signature for any message with knowing a previously valid threshold proxy signature. In addition, their scheme also suffers from the weakness that the proxy signers might change the threshold value. That is, the proxy signers can arbitrarily modify the threshold strategy without being detected by the original signer or verifiers, which might violate the original signer＇s intent. Furthermore, we propose an improved scheme that remedies the weaknesses of Bao et al＇s scheme. The improved scheme satisfies all secure requirements for threshold proxy signature.

A Data Transmission Approach Based on Ant Colony Optimization and Threshold Proxy Re-encryption in WSNs

Wireless sensor networks(WSNs)have become increasingly popular due to the rapid growth of the Internet of Things.As open wireless transmission media are easy to attack,security is one of the primary design concerns for WSNs.Current solutions consider routing and data encryption as two isolated issues,providing incomplete security.Therefore,in this paper,we divide the WSN communication process into a data path selection phase and a data encryption phase.We propose an improved transmission method based on ant colony optimization(ACO)and threshold proxy re-encryption for WSNs,and we named it as ACOTPRE.The method resists internal and external attacks and ensures safe and efficient data transmission.In the data path selection stage,the ACO algorithm is used for network routing.The improvement of the pheromone concentration is proposed.In order to resist attacks from external attackers,proxy re-encryption is extended to WSN in the data encryption stage.The threshold secret sharing algorithm is introduced to generate a set of re-encryption key fragments composed of random numbers at the source node.We confirm the performance of our model via simulation studies.

Secure Chained Threshold Proxy Signature without and with Supervision

Threshold Proxy Signature (TPS) scheme facilitates a manager to delegate his signing capability to a group of n2 sub-ordinates without revealing his own private key, such that a subgroup of at least t2 ≤ n2 subordinates is required to generate a proxy signature. In reality, the situation can be more complicated. First of all, the subgroup may further delegate their proxy signing capabilities to another group of n3 subordinates such that at least another subgroup of at least t3 ≤ n3 subordinates are of the proxy signing capabilities (in the form of a chain). t2 can be unequal to t3 depending on the concrete requirement. This is a group-to-group delegation problem. In addition, a supervising agent (SA) may be introduced in the above chain to supervise the subordinates, such that proxy signing can only be successfully executed with SA’s agreement. This is a delegation with supervision problem in the threshold delegation chain described above. These two extensions of delegation problems are not solved yet. This paper designs two provably secure cryptographic schemes Chained Threshold Proxy Signature (CTPS) scheme and Chained Threshold Proxy Signature with Supervision (CTPSwS) scheme to solve these two delegation problems.

面向预制食品溯源的隐私数据加密共享方法研究

随着区块链技术在食品溯源领域的发展,预制食品的质量安全得到了有效保障。然而,预制食品上下游生产加工环节众多的产业特点,使溯源变得困难。在溯源的同时安全共享食谱、秘方等隐私数据,使供应链更好地协同生产则十分重要。为解决上述问题,提出了一种面向预制食品溯源的门限代理重加密(Threshold proxy re-encryption)隐私数据共享的方法,设计了一条预制食品溯源区块链和追溯生产批号关联相关溯源数据,确保数据的真实可信。使用门限代理重加密,预制食品生产商通过门限代理重加密将研发的食谱加密为初加密密文,同时在本地生成重加密密钥,将初加密密文与重加密密钥上传至预制食品溯源区块链中;第三方半诚实服务商将从区块链上获取的重加密材料进行重加密生成重加密密文,将重加密密文上传至区块链;监管部门等数据访问者则使用自身私钥将从区块链上获取的重加密密文进行重加密解密,实现隐私数据在溯源区块链上的安全共享。该方法基于Hyperledger Fabric,搭建了一个预制食品溯源区块链原型系统进行测试。测试结果表明,所提出的面向预制食品溯源的隐私数据加密共享方法在隐私数据共享方面与常用的数据加密共享方法相比计算开销较低。数据上链、公开数据查询、隐私数据查询的平均时延分别为1473.8、63.9、59.9 ms,系统性能良好。实验结果表明,提出的方法达到了供应链隐私数据安全共享的目的,确保了商业机密和知识产权的安全共享,对预制食品行业发展和食品安全提升具有参考价值。

一种改进条件广播代理重加密的数据共享方案

传统的条件广播代理重加密数据共享方式过度依赖不可信第三方代理商,存在效率低、数据安全和隐私泄露等问题。针对以上问题,提出了一种将条件广播代理重加密与区块链共识机制相结合的信息安全保障方案。首先,为解决单个代理商的单点故障以及合谋攻击问题,所提方案使用区块链节点轮流担任代理商节点,同时利用融合信誉机制的委托权益证明共识算法筛选出高信誉度的代理商节点参与重加密过程,大大降低了单点故障和合谋攻击的风险。其次,针对代理商节点对重加密密钥使用的高权限问题,引入门限密钥思想,将重加密密钥分割为多个片段,这些片段分布于不同的代理商节点上。通过这种方式,任何单个代理商节点都无法单独完成数据的解密,从而有效提高了重加密过程的安全性。最后,通过对方案的安全性、正确性和可信度进行分析,表明提出的方案能有效解决传统方案中的安全隐患。仿真实验结果证明,与现有数据共享方案相比,所提方案在保障数据安全方面具有明显优势,同时计算成本较低。

可监管的工业物联网数据共享方案

针对当前工业数据共享存在中心化、监管困难和数据安全等问题,提出了一种在工业物联网环境下的安全、高效和可监管的数据共享方案。该方案引入监管机构来控制授权令牌发放,保证数据共享活动的可控性。结合门限代理重加密和区块链技术,将系统初始化和重加密任务分配给共识节点来完成,减轻系统计算开销。利用智能合约和零知识证明技术自动验证数据的有效性,保障了数据用户的权益。此外,高效的共识算法提高了区块链系统处理交易的速率。经安全性分析和性能分析表明,该方案在大规模工业数据共享场景中能更加安全高效地共享数据。

代理签名的现状与进展

首先描述了代理签名产生的背景、现状与进展。然后,介绍了代理签名的概念、要求、分类与述评,给出了几种典型的代理签名方案,并进行相应的分析与述评。最后,指出了目前代理签名方案存在的问题, 并且对未来的研究方向进行了展望。

基于RSA密码体制的门限代理签名

在一个(t,n)门限代理签名体制中,原始签名者可以将他的签名权利以门限的方式委托给n个代理签名者,至少t个代理签名者合作,可以产生相应的代理签名,而任何少于t个代理签名者则不能.目前已经有很多基于离散对数问题的门限代理签名方案,但是并没有出现一个真正意义上的基于RSA密码体制的门限代理签名方案.鉴于RSA在理论及应用中的重要性,基于RSA构造门限代理签名体制是必要的.文中借助于RSA秘密共享的思想,构造了一个安全、有效的RSA门限代理签名方案.在文中的方案中,没有使用可信权威,所有的秘密参数都是由参与者分布式产生的.

具有已知代理人的不可否认门限代理签密方案(英文)

1996年,Mambo等人提出了代理签名概念.但是,代理签名仅能提供授权的认证而不能提供保密性.Chan和Wei提出一个门限代理签密方案(记为Chan-Wei方案),扩展了代理签名的概念.指出他们的方案不满足强不可伪造性、强不可否认性和强识别性.基于Chan-Wei方案,提出一个能够克服Chan-Wei方案缺点的不可否认门限代理签密方案.给出方案的完备性证明和安全性分析.此外,与Chan-Wei方案相比,所提出的方案能够确切地发现哪些代理人提供假子密钥或篡改子密钥.

Web智能代理的预取技术和缓存技术

针对同一个工作组中成员可能对 Web有相似的兴趣点和访问习惯问题 ,研究了主要包括缓存和预取两个部分的智能代理技术 ;研究了代理缓存三种替换算法 :L RU和 L RU的两种变种 .仿真试验表明 ,L RU算法的命中率极差 ,将 L RU的两种变种相结合则是一种较好的方案 .通过引入预测算法和门限算法 ,代理服务器可以预测最近将要访问到的页面 ,并在客户实际请求提出之前有选择地下载 .因为单个客户访问某个页面的历史次数往往不够多 ,将预测算法放在代理服务器上比放在客户端的预测概率更准确 .通过在代理服务器上实现缓存和预取技术 ,可减少用户访问 Web的响应时间 ,还可减少实际访问 Web服务器的总次数 .并提出了一个为发展中国家用户缩减

一个门限代理签名方案的改进

1996年 Mambo,Usuda和 Okamoto提出了代理签名的概念 ,即在一个代理签名方案中 ,一个被指定的代理签名人可以代表原始签名人生成有效的代理签名 .Mambo,U suda和 Okam oto指出代理签名方案应满足不可否认性、可验证性、不可伪造性、可区分性等性质并给出 3种类型的代理签名 :完全代理签名 ,部分代理签名和带有授权证书的代理签名 .Sun,L ee和 Hwang提出了一个门限代理签名方案 (记为 S- L- H方案 ) ,分别克服了由Zhang和 Kim等提出的门限代理签名方案的缺点并给出了一个改进方案 .这里指出 S- L- H方案不能抵抗公钥替换攻击 ,并给出了一个改进的门限代理签名方案 .进一步利用零知识的思想给出了抵抗公钥替换攻击的一般方法 .改进后的方案除具有 S- L- H方案的安全性外 ,还具有不可否认性、不使用安全信道、能抵抗公钥替换攻击和合谋攻击等特点 .