Strong proxy signature scheme with proxy signer privacy protection.

by Shum Kwan.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.Includes bibliographical references (leaves 30-32).Abstracts in English and Chinese.Acknowledgement --- p.iiAbstract --- p.iii□ □ --- p.ivChapter 1 . --- Introduction --- p.1Chapter 1.1 --- Introduction to topic --- p.1Chapter 1.2 --- What is proxy signature? --- p.2Chapter 1.3 --- Terminologies in proxy signature --- p.2Chapter 1.4 --- Levels of delegation --- p.3Chapter 1.5 --- Previous work on Proxy Signature --- p.4Chapter 1.6 --- Our Contributions --- p.4Chapter 1.7 --- Thesis Organization --- p.4Chapter 2. --- Backgroun d --- p.6Chapter 2.1 --- Digital Signature --- p.6Chapter 2.2 --- Digital Certificate and CA --- p.6Chapter 2.3 --- Hash Functions --- p.7Chapter 2.4 --- Bit commitment --- p.7Chapter 3. --- Brief introduction to Our Result --- p.8Chapter 3.1 --- A Proxy Signature Scheme with Proxy Signer Privacy Protection --- p.8Chapter 3.2 --- Applications of Proxy Signature --- p.9Chapter 4. --- Detail Explanation of Certified Alias and its Application on Proxy Signature --- p.10Chapter 4.1 --- Introduction --- p.10Chapter 4.2 --- Protecting Signer Privacy Using Certified Alias Definition 4.2.3 --- p.10Chapter 4.3 --- Constructing Proxy signature Scheme by Consecutive Execution of Cryptographic Primitives (Scheme CE) --- p.11Chapter 4.4 --- Constructing Proxy signature Scheme by Direct Form Equations (Scheme DF) --- p.15Chapter 4.5 --- Comparison between scheme CE and scheme DF --- p.19Chapter 4.6 --- Chapter Summary --- p.20Chapter 5 . --- Applications of Proxy Signature with Proxy Signer Privacy Protection --- p.21Chapter 5.1 --- Secure Mobile agent Signature with Itinerary Privacy --- p.21Chapter 5.1.1 --- Introduction to Mobile Agent --- p.21Chapter 5.1.2 --- "Review on Lee, et al. strong non-designated proxy signature scheme for mobile agents" --- p.21Chapter 5.1.3 --- Constructing Signature scheme for Mobile Agent using Proxy signature with Proxy Signer Privacy Protection --- p.22Chapter 5.1.4 --- Remarks --- p.23Chapter 5.2 --- Group Signature with Unlimited Group Size --- p.24Chapter 5.2.1 --- Introduction to group signature --- p.24Chapter 5.2.2 --- Constructing group signature scheme using certified alias --- p.24Chapter 5.2.4 --- Remarks --- p.26Chapter 5.3 --- Chapter Summary --- p.27Chapter 6. --- Conclusions --- p.28Appendix: Paper derived from this thesis --- p.29Bibliography --- p.3

Secure Mobile Agents in Electronic Commerce by Using Undetachable Signatures from Pairings

It is expect that mobile agents technology will bring significant benefits to electronic commerce. But security issues, especially threats from malicious hosts, become a great obstacle of widespread deployment of applications in electronic commerce based on mobile agents technology. Undetachable digital signature is a category of digital signatures to secure mobile agents against malicious hosts. An undetachable signature scheme by using encrypted functions from bilinear pairings was proposed in this paper. The security of this scheme base on the computational intractability of discrete logarithm problem and computational Diffe-Hellman problem on gap Diffle-Hellman group. Furthermore, the scheme satisfies all the requirements of a strong non-designated proxy signature i.e. verifiability, strong unforgeability, strong identifiability, strong undeniability and preventions of misuse. An undetachable threshold signature scheme that enable the customer to provide n mobile agents with ‘shares’ of the undetachable signature function is also provided. It is able to provide more reliability than classical undetachable signatures

Secure Identification in Social Wireless Networks

The applications based on social networking have brought revolution towards social life and are continuously gaining popularity among the Internet users. Due to the advanced computational resources offered by the innovative hardware and nominal subscriber charges of network operators, most of the online social networks are transforming into the mobile domain by offering exciting applications and games exclusively designed for users on the go. Moreover, the mobile devices are considered more personal as compared to their desktop rivals, so there is a tendency among the mobile users to store sensitive data like contacts, passwords, bank account details, updated calendar entries with key dates and personal notes on their devices. The Project Social Wireless Network Secure Identification (SWIN) is carried out at Swedish Institute of Computer Science (SICS) to explore the practicality of providing the secure mobile social networking portal with advanced security features to tackle potential security threats by extending the existing methods with more innovative security technologies. In addition to the extensive background study and the determination of marketable use-cases with their corresponding security requirements, this thesis proposes a secure identification design to satisfy the security dimensions for both online and offline peers. We have implemented an initial prototype using PHP Socket and OpenSSL library to simulate the secure identification procedure based on the proposed design. The design is in compliance with 3GPP‟s Generic Authentication Architecture (GAA) and our implementation has demonstrated the flexibility of the solution to be applied independently for the applications requiring secure identification. Finally, the thesis provides strong foundation for the advanced implementation on mobile platform in future

CONSTRUCTION OF EFFICIENT AUTHENTICATION SCHEMES USING TRAPDOOR HASH FUNCTIONS

In large-scale distributed systems, where adversarial attacks can have widespread impact, authentication provides protection from threats involving impersonation of entities and tampering of data. Practical solutions to authentication problems in distributed systems must meet specific constraints of the target system, and provide a reasonable balance between security and cost. The goal of this dissertation is to address the problem of building practical and efficient authentication mechanisms to secure distributed applications. This dissertation presents techniques to construct efficient digital signature schemes using trapdoor hash functions for various distributed applications. Trapdoor hash functions are collision-resistant hash functions associated with a secret trapdoor key that allows the key-holder to find collisions between hashes of different messages. The main contributions of this dissertation are as follows: 1. A common problem with conventional trapdoor hash functions is that revealing a collision producing message pair allows an entity to compute additional collisions without knowledge of the trapdoor key. To overcome this problem, we design an efficient trapdoor hash function that prevents all entities except the trapdoor key-holder from computing collisions regardless of whether collision producing message pairs are revealed by the key-holder. 2. We design a technique to construct efficient proxy signatures using trapdoor hash functions to authenticate and authorize agents acting on behalf of users in agent-based computing systems. Our technique provides agent authentication, assurance of agreement between delegator and agent, security without relying on secure communication channels and control over an agent’s capabilities. 3. We develop a trapdoor hash-based signature amortization technique for authenticating real-time, delay-sensitive streams. Our technique provides independent verifiability of blocks comprising a stream, minimizes sender-side and receiver-side delays, minimizes communication overhead, and avoids transmission of redundant information. 4. We demonstrate the practical efficacy of our trapdoor hash-based techniques for signature amortization and proxy signature construction by presenting discrete log-based instantiations of the generic techniques that are efficient to compute, and produce short signatures. Our detailed performance analyses demonstrate that the proposed schemes outperform existing schemes in computation cost and signature size. We also present proofs for security of the proposed discrete-log based instantiations against forgery attacks under the discrete-log assumption

Secure Mobile Agents with Designated Hosts

Mobile agents often travel in a hostile environment where their security and privacy could be compromised by any party including remote hosts in which agents visit and get services. It was proposed in the literature that the host visited by an agent should jointly sign a service agreement with the agent\u27s home, where a proxy-signing model was deployed and every host in the agent system can sign. We observe that this actually poses a serious problem in that a host that should be excluded from an underlying agent network could also send a signed service agreement. In order to solve this problem, we propose a secure mobile agent scheme achieving host authentication with designated hosts, where only selected hosts can be included in the agent network. We also present a security model and provide a rigorous security proof to our scheme

Nominative Proxy Signature Schemes

In a nominative proxy signature scheme, an original singer delegates his signing power to a proxy, who generates a nominative signature on behalf of the original signer. In a nominative proxy signature scheme, only the nominee can verify the signature and if necessary, only the nominee can prove its validity to the third party. In this paper, we first classify the nominative proxy signature into two types, original-nominative proxy signature and proxy-nominative proxy signature. Then we analyze the nominative proxy scheme proposed by Park and Lee. We show that the scheme suffers from universal verification. We also point out that the scheme presented by S.-H. Seo and S.-H. Lee is insecure and the scheme cannot provide non-repudiation. Finally we present our nominative proxy signature schemes which overcome the weakness mentioned above. Compared with the scheme recently proposed by G.-L. Wang, our scheme is more efficient