Verifiably encrypted cascade-instantiable blank signatures to secure progressive decision management

National Research Foundation (NRF) Singapore under NC

Fair signature exchange via delegation on ubiquitous networks

This paper addresses the issue of autonomous fair signature exchange in emerging ubiquitous (u-) commerce systems, which require that the exchange task be delegated to authorised devices for its autonomous and secure execution. Relevant existing work is either inefficient or ineffective in dealing with such delegated exchange. To rectify this situation, this paper aims to propose an effective, efficient and secure solution to the delegated exchange to support the important autonomy feature offered by u-commerce systems. The proposed work includes a novel approach to symmetric-key based verifiable proxy encryption to make the exchange delegation flexible, efficient and simple to implement on resource-limited devices commonly used in u-commerce systems. This approach is then applied to design a new exchange protocol. An analysis of the protocol is also provided to confirm its security and fairness. Moreover, a comparison with related work is presented to demonstrate its much better efficiency and simplicity

Pairing-Based Cryptographic Protocols : A Survey

The bilinear pairing such as Weil pairing or Tate pairing on elliptic and hyperelliptic curves have recently been found applications in design of cryptographic protocols. In this survey, we have tried to cover different cryptographic protocols based on bilinear pairings which possess, to the best of our knowledge, proper security proofs in the existing security models

ID-based, proxy, threshold signature scheme

We propose the proxy threshold signature scheme with the application of elegant construction of verifiable delegating key in the ID-based infrastructure, and also with the bilinear pairings. The protocol satisfies the classical security requirements used in the proxy delegation of signing rights. The description of the system architecture and the possible application of the protocol in edge computing designs is enclosed

Public Key Infrastructure based on Authentication of Media Attestments

Many users would prefer the privacy of end-to-end encryption in their online communications if it can be done without significant inconvenience. However, because existing key distribution methods cannot be fully trusted enough for automatic use, key management has remained a user problem. We propose a fundamentally new approach to the key distribution problem by empowering end-users with the capacity to independently verify the authenticity of public keys using an additional media attestment. This permits client software to automatically lookup public keys from a keyserver without trusting the keyserver, because any attempted MITM attacks can be detected by end-users. Thus, our protocol is designed to enable a new breed of messaging clients with true end-to-end encryption built in, without the hassle of requiring users to manually manage the public keys, that is verifiably secure against MITM attacks, and does not require trusting any third parties

Securing Smart Grid In-Network Aggregation through False Data Detection

Existing prevention-based secure in-network data aggregation schemes for the smart grids cannot e ectively detect accidental errors and falsified data injected by malfunctioning or compromised meters. In this work, we develop a light-weight anomaly detector based on kernel density estimator to locate the smart meter from which the falsified data is injected. To reduce the overhead at the collector, we design a dynamic grouping scheme, which divides meters into multiple interconnected groups and distributes the verification and detection load among the root of the groups. To enable outlier detection at the root of the groups, we also design a novel data re-encryption scheme based on bilinear mapping so that data previously encrypted using the aggregation key is transformed in a form that can be recovered by the outlier detectors using a temporary re-encryption key. Therefore, our proposed detection scheme is compatible with existing in-network aggregation approaches based on additive homomorphic encryption. We analyze the security and eÿciency of our scheme in terms of storage, computation and communication overhead, and evaluate the performance of our outlier detector with experiments using real-world smart meter consumption data. The results show that the performance of the light-weight detector yield high precision and recall

Role Signatures for Access Control in Grid Computing

Implementing access control efficiently and effectively in an open and distributed grid environment is a challenging problem. One reason for this is that users requesting access to remote resources may be unknown to the authorization service that controls access to the requested resources. Hence, it seems inevitable that pre-defined mappings of principals in one domain to those in the domain containing the resources are needed. A second problem in such environments is that verifying the authenticity of user credentials or attributes can be difficult. In this paper, we propose the concept of role signatures to solve these problems by exploiting the hierarchical structure of a virtual organization within a grid environment. Our approach makes use of a hierarchical identity-based signature scheme whereby verification keys are defined by generic role identifiers defined within a hierarchical namespace. We show that individual member organizations of a virtual organization are not required to agree on principal mappings beforehand to enforce access control to resources. Moreover, user authentication and credential verification is unified in our approach and can be achieved through a single role signature

Advances in signatures, encryption, and E-Cash from bilinear groups

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 147-161).We present new formal definitions, algorithms, and motivating applications for three natural cryptographic constructions. Our constructions are based on a special type of algebraic group called bilinear groups. 1. Re-Signatures: We present the first public key signature scheme where a semi-trusted proxy, given special information, can translate Alice's signature on a message into Bob's signature on the same message. The special information, however, allows nothing else, i.e., the proxy cannot translate from Bob to Alice, nor can it sign on behalf of either Alice or Bob. We show that a path through a graph can be cheaply authenticated using this scheme, with applications to electronic passports. 2. Re-Encryption: We present the first public key cryptosystem where a semi-trusted proxy, given special information, can translate an encryption of a message under Alice's key into an encryption of the same message under Bob's key. Again, the special information allows nothing else, i.e. the proxy cannot translate from Bob to Alice, decrypt on behalf of either Alice or Bob, or learn anything else about the message. We apply this scheme to create a new mechanism for secure distributed storage.(cont.) 3. Compact; E-Cash with Tracing and Bounded-Anonymity: We present an offline e-cash system where 2 coins can be stored in O(e + k) bits and withdrawn or spent in 0(f + k) time, where k is the security parameter. The best previously known schemes required at least one of these complexities to be 0(2t . k). In our system, a user's transactions are anonymous and unlinkable, unless she performs a forbidden action, such as double-spending a coin. Performing a forbidden action reveals the identity of the user, and optionally allows to trace all of her past transactions. We provide solutions without using a trusted party. We argue why features of our system are likely to be crucial to the adoption of any e-cash system.by Susan Hohenberger.Ph.D