6786934
Concurrently Non-Malleable Zero Knowledge in the Authenticated Public-Key Model
We consider a type of zero-knowledge protocols that are of interest for their practical applications within networks like the Internet: efficient zero-knowledge arguments of knowledge that remain secure against concurrent man-in-the-middle attacks. As negative results in the area of concurrent non-malleable zero-knowledge imply that protocols in the standard setting (i.e., under no setup assumptions) can only be given for trivial languages, researchers have studied such protocols in models with setup assumptions, such as the common reference string (CRS) model. This model assumes that a reference string is honestly created at the beginning of all interactions and later available to all parties (an assumption that is satisfied, for instance, in the presence of a trusted party). A growing area of research in Cryptography is that of reducing the setup assumptions under which certain cryptographic protocols can be realized. In an effort to reduce the setup assumptions required for efficient zeroknowledge arguments of knowledge that remain secure against concurrent man-in-the-middle attacks, we consider a model, which we call the Authenticated Public-Key (APK) model. The APK model seems to significantly reduce the setup assumptions made by the CRS model (as no trusted party or honest execution of a centralized algorithm are required), and can be seen as a slightly stronger variation of the Bare Public-Key (BPK) model from [8, 30], and a weaker variation of the registered public-key model used in [3]. We then define and study man-in-the-middle attacks in the APK model. Our main result is a constant-round concurrent non-malleable zero-knowledge argument of knowledge for any polynomial-time relation (associated to a language in NP), under the (minimal) assumption of the existence of a one-way function family. We also show time-efficient instantiations of our protocol, in which the transformation from a 3-round honest-verifier zero-knowledge argument of knowledge to a 4-round concurrently non-malleable zero-knowledge argument of knowledge for the same relation incurs only O(1) (precisely, a small constant) additional modular exponentiations, based on known number-theoretic assumptions. Furthermore, the APK model is motivated by the consideration of some man-inthe-middle attacks in models with setup assumptions that had not been considered previously and might be of independent interest. We also note a negative result with respect to further reducing the setup assumptions of our protocol to those in the (unauthenticated) BPK model, by showing that concurrently non-malleable zero-knowledge arguments of knowledge in the BPK model are only possible for trivial languages.
26482984
Resettable Zero Knowledge with Concurrent Soundness in the Bare Public-Key Model under Standard Assumption
In this paper we present the firstconstant round resettable zero knowledge arguments with concurrent soundness for $\mathcal{NP}$ in the bare public-key (BPK for short) model assuming only collision-resistant hash functions against polynomial-timeadversaries. This resolves the problem whether there exist such protocols for $\mathcal{NP}$ in BPK model without assuming sub-exponential hardness. In our protocol, the resettable zero knowledge is demonstrated via a black-box simulator, while the concurrent soundness is proved by using the malicious prover strategy in non-black-boxmanner.
280798
Instance-Dependent Verifiable Random Functions and Their Application to Simultaneous Resettability
We introduce a notion of instance-dependent verifiable random functions(InstD-VRFs for short). Informally, an InstD-VRF is, in some sense, a verifiable random function [23] with a special public key, which is generated via a (possibly)interactiveprotocol and contains an instance y? L? {0,1}*for a specific NP language L, but the security requirements on such a function are relaxed: we only require the pseudorandomnessproperty when y? Land only require the uniquenessproperty when y? L, instead of requiring both pseudorandomness and uniqueness to hold simultaneously. We show that this notion can be realized under standard assumption. 
 
Our motivation is the conjecture posed by Barak et al.[2], which states there exist resettably-sound resettable zero knowledge arguments for NP. The instance-dependent verifiable random functions is a powerful tool to tackle this problem. We first use them to obtain two interesting instance-dependent argument systems from the Barak's public-coin bounded concurrent zero knowledge argument [1], and then, we 
 
 1 Construct the first(constant round) zero knowledge arguments for NP enjoying a certainsimultaneous resettability under standard hardness assumptions in the plain model, which we call bounded-class resettable ZK arguments with weak resettable-soundness Though the malicious party (prover or verifier) in such system is limited to a kind of bounded resetting attack, We put NO restrictions on the number of the total resets made by malicious party. 
 1 show that, under standard assumptions, if there exist public-coin concurrent zero knowledge arguments for NP, there exist the resettably-sound resetable zero knowledge arguments for NP.
23293268
Novel Ω-protocols for NP
AbstractΩ-protocols, introduced by Garay, Mackenzie and Yang, is a variant of S-protocols with online extractor which is a useful tool to overcome the nest effect in concurrent scenario. In this work, we construct an Ω-protocol for Hamiltonian cycle problem, and therefore, it allows us to present Ω-protocol for any NP relation. For most general NP relations, our construction of Ω-protocols is much more efficient than the informal one described by Garay et al. and we believe that the method for our construction may be of independent interest.
29420806
Strengthening QIM-Based Watermarking by Non-uniform Discrete Cosine Transform
Being extremely precise and at a low loss of perceptual quality, the attacks of value modification and optimized noise reduction still threaten the watermarking based on quantization index modulation (QIM). To resist them, the paper constructs a non-uniform discrete cosine transform (NDCT), and brings out an NDCT-QIM watermarking scheme, which embeds a watermark in a private NDCT domain with the parameters of NDCT as a secret key. The technique blinds the value modification by dispersing the attacking signal and changing its energy in the embedded domain. Because of the variable power spectrum of a watermark, the noise reduction becomes non-optimal. Some other advantages, including the ease of embedding, computational simplicity, etc., can also be acquired or maintained by the use of NDCT.
3145299
Resettable Zero Knowledge in the Bare Public-Key Model under Standard Assumption
In this paper we resolve an open problem regarding resettable zero knowledge in the bare public-key (BPK for short) model: Does there exist constant round resettable zero knowledge argument with concurrent soundness for $\mathcal{NP}$ in BPK model without assuming \emph{sub-exponential hardness}? We give a positive answer to this question by presenting such a protocol for any language in $\mathcal{NP}$ in the bare public-key model assuming only collision-resistant hash functions against \emph{polynomial-time} adversaries.
1830896
A Communication Virtual Machine
The convergence of data, voice and multimedia communication over digital networks, coupled with continuous improvement in network capacity and reliability has significantly enriched the ways we communicate. However, the stovepipe approach used to develop today's communication applications and tools results in rigid technology, limited utility, lengthy and costly development cycle, difficulty in integration, and hinders innovation. In this paper, we present a fundamentally different approach, which we call communication virtual machine (CVM) to address these problems. CVM provides a user-centric, model-driven approach for conceiving, synthesizing and delivering communication solutions across application domains. We argue that CVM represents a far more effective paradigm for engineering communication solutions. The concept, architecture, modeling language, prototypical design and implementation of CVM are discussed
11078034
A HyperNet Model for Large Hypertext Systems
Two major problems with large hypertext systems are the user disorientation and lack of search ability. The problems, we believe, are mainly caused by the lack of semantics and modularity in hypertext data models. In this paper, a HyperNet model is proposed as a data model for large hypertext systems aimed at the above problems, which features strong modularity, attribute-based link semantics and capability of organizing information in various levels of abstraction. Based on the model, User View (UV), Local-HyperNet and Global GSP View (GGSPV) ate proposed as the user’s access contexts, each of which emphasizes different aspects of the user access and compensate the weakness of the others. Algorithms are also provided to automatically generate and update user views. Two browsing schemes, namely automatic browsing and user-controlled multi-level browsing, are presented to provide flexible navigation in the database and to remit the disorientation problem. At last, a concurrent search algorithm is proposed to provide efficient search/query in (potentially distributed) hypertext systems.
16690202
Formally analyzing software architectural specifications using SAM
In the past decade, software architecture has emerged as a major research area in software engineering. Many architecture description languages have been proposed and some analysis techniques have also been explored. In this paper, we present a graphical formal software architecture description model called software architecture model (SAM). SAM is a general software architecture development framework based on two complementary formalisms--Petri nets and temporal logic. Petri nets are used to visualize the structure and model the behavior of software architectures while temporal logic is used to specify the required properties of software architectures. These two formal methods are nicely integrated through the SAM software architecture framework. Furthermore, SAM provides the flexibility to choose different compatible Petri net and temporal logic models according to the nature of system under study. Most importantly, SAM supports formal analysis of software architecture properties in a variety of well-established techniques--simulation, reachability analysis, model checking, and interactive proving, In this paper, we show how to formally analyze SAM software architecture specifications using two well-known techniques--symbolic model checking with tool Symbolic Model Verifier, and theorem proving with tool STeP.
2017069
Model checking software architecture specifications in SAM
In the past decade, software architecture research has mainly focused on the concept formulation and the development of various architecture description languages. This field has matured enough and thus requires more emphasis on validation techniques. Symbolic model checking has been a highly successful automatic validation technique for hardware systems. We are interested in whether symbolic model checking can be effectively applied to software architecture validation. In this paper, we present our approach to apply the symbolic model checking technique to verify software architecture specifications written in SAM.
30407300
A G-Net Model for Knowledge Representation and Reasoning
The G-net model for G-type knowledge representation is introduced. It is capable of modeling both static semantic knowledge and dynamic control knowledge, combining them into a loosely coupled, mixed-type knowledge hierarchy. Four reasoning algorithms for the G-net model are proposed: inheritance reasoning and recognition reasoning for semantic knowledge, event-driven reasoning for dynamic knowledge, and control table reasoning for coordination and control in a mixed-type knowledge hierarchy. Based on the knowledge-table representation, the G-net model expresses the constraints and relationships among knowledge objects explicitly so that reasoning algorithms can be implemented efficiently. Applications to information systems prototyping are discussed. >