18477384
Verifiable Shuffle of Large Size Ciphertexts
A shuffle is a permutation and rerandomization of a set of ciphertexts. Among other things, it can be used to construct mix-nets that are used in anonymization protocols and voting schemes. While shuffling is easy, it is hard for an outsider to verify that a shuffle has been performed correctly. We suggest two efficient honest verifier zero-knowledge (HVZK) arguments for correctness of a shuffle. Our goal is to minimize round-complexity and at the same time have low communicational and computational complexity. 
 
The two schemes we suggest are both 3-move HVZK arguments for correctness of a shuffle. We first suggest a HVZK argument based on homomorphic integer commitments, and improve both on round complexity, communication complexity and computational complexity in comparison with state of the art. The second HVZK argument is based on homomorphic commitments over finite fields. Here we improve on the computational complexity and communication complexity when shuffling large ciphertexts.
896953
Sequential Aggregate Signatures and Multisignatures Without Random Oracles
We present the first aggregate signature, the first multisignature, and the first verifiably encrypted signature provably secure without random oracles. Our constructions derive from a novel application of a recent signature scheme due to Waters. Signatures in our aggregate signature scheme are sequentially constructed, but knowledge of the order in which messages were signed is not necessary for verification. The aggregate signatures obtained are shorter than Lysyanskaya et al. sequential aggregates and can be verified more efficiently than Boneh et al. aggregates. We also consider applications to secure routing and proxy signatures.
3519878
Self-securing ad hoc wireless networks
Mobile ad hoc networking offers convenient infrastructureless communication over the shared wireless channel. However, the nature of ad hoc networks makes them vulnerable to security attacks. Examples of such attacks include passive eavesdropping over the wireless channel, denial of service attacks by malicious nodes and attacks from compromised nodes or stolen devices. Unlike their wired counterpart, infrastructureless ad hoc networks do not have a clear line of defense, and every node must be prepared for encounters with an adversary. Therefore, a centralized or hierarchical network security solution does not work well.This work provides scalable, distributed authentication services in ad hoc networks. Our design takes a self-securing approach, in which multiple nodes (say, k) collaboratively provide authentication services for other nodes in the network. We first formalize a localized trust model that lays the foundation for the design. We further propose refined localized certification services based on our previous work, and develop a new scalable share update to resist more powerful adversaries. Finally, we evaluate the solution through simulation and implementation.
1954441
A Sufficient and Necessary Condition for the Consistency of XML DTDs
Recently, XML has emerged as a standard for representing and exchanging data on the World Wide Web. As a result, there is a trend of increasing amount of XML documents that publish information on the Web from various data sources. A Document Type Definition (DTD) describes the structure of a set of similar XML documents and serves as the schema for XML documents. The World Wide Web Consortium has defined the grammar for specifying DTDs; however, even a syntactically correct DTD might be inconsistent in the sense that there exist no XML documents conforming to the structure imposed by the DTD. In this paper, we formalize the notion of the consistency of DTDs, and identify a sufficient and necessary condition for a DTD to be consistent.
44527180
A Robust Data Delivery Protocol for Large Scale Sensor Networks
Recent technology advances in low-cost, low-power chip designs have made feasible the deployment of large-scale sensor networks. Although data forwarding has been among the first set of issues explored in sensor networking, how to reliably deliver sensing data through a vast field of small, vulnerable sensors remains a research challenge. In this paper we present GRAdient Broadcast (GRAB), a new set of mechanisms and protocols which is designed specifically for robust data delivery in spite of unreliable nodes and fallible wireless links. Similar to previous work [1], GRAB builds and maintains a cost field, providing each sensor in the network the direction to forward sensing data. Different from all the existing approaches, however, GRAB forwards data along an interleaved mesh from each source to the receiver. The width of the forwarding mesh is controlled by the amount of credit carried in each data message, allowing the degree of delivery robustness to be adjusted by the sender. GRAB design harnesses the advantage of large scale and relies on the collective efforts of multiple nodes to deliver data, without dependency on any individual ones. As demonstrated in our extensive simulation experiments, GRAB can successfully deliver above 90% of data with relatively low energy cost even under adverse conditions of up to 30% node failures compounded with 15% link packet losses.
41181604
The Semantic Web: opportunities and challenges for next-generation Web applications
18131628
Automatic workflow verification and generation
Correctness is an important aspect of workflow management systems. However, most of the workflow literature focuses only on the modeling aspects and assumes that a workflow is correct if during the execution it respects the control and data dependency specified by the workflow designer. To address the correctness question properly we propose a new workflow model based on Hoare semantics that allows to: (1) automatically check if the desired outcome of a workflow can be produced by its actual implementation, (2) automatically synthesize a workflow implementation from the workflow specification and a given task library.In particular we: (1) formalize the semantics of workflows and tasks with pre-and postconditions, (2) for each control construct we provide a set of sound inference rules formalizing its semantics. While most of our workflow constructs are standard, two of them are new: the universal and the existential constructs. We then describe algorithms for automatically checking the correctness of workflows and for automatic workflow generation.