This paper proposes a forward-secure undeniable digital signature scheme based on zero-knowledge proof.By combining the undeniable digital signature with the forward-secure digital signature,the new scheme keeps the general property of undeniable digital signature,and has the character of forward-secure,namely,the loss can be reduced to the lowest once the secret key is lost(or stolen).The scheme has some features such as undeniable and unforgeable of the digital signature,and the size of key and signature are short.The idea of zero-knowledge proof is used in key update protocol,which guarantees key update is secure.The scheme is secure under the assumption of standard intractability problems.
By imitating the zero-knowledge proof protocol of RSA digital signature,we get a faulty zero-knowledge proof protocol of EIGamal digital signature.And this paper will analyze it.
Access control in decentralised collaborative systems present huge challenges especially where many autonomous entities including organizations, humans, software agents from different security domains seek to access and share resources in a secure and controlled way. Automated trust negotiation (ATN) is one approach that has been proposed for trust discovery and realisation, which enables entities viz. strangers to access resources across autonomous boundaries through iterative exchange of credentials. Various negotiation strategies have been proposed to protect credential disclosure during trust negotiations. However in some domains such as e-health, not all entities are willing to negotiate credentials or disclose access policies directly to strangers regardless of negotiation strategies and instead prefer to negotiate and disclose sensitive information only to strangers within what we refer to as a circle of trust. In this paper, we introduce a formal model to describe how locally trusted intermediary parties can provide multiple negotiation and delegations hops to protect credentials and access policies. We propose a dynamic trust negotiations (DTN) model that not only protects sensitive information from disclosure but also reduces semantic issues that exist with credentials in decentralized systems. This work is currently being explored and implemented within the e-health domain: specifically in the MRC-funded Virtual Organisation for Trials of Epidemiological Studies (VOTES) project
An improved confirmer digital signature scheme was presented based on the analysis of the disadvantages of traditional confirmer signature algorithm and the introduction of zero-knowledge proof. In this scheme, signer need not directly provide his signature to the information, he just need to provide a zero-knowledge to prove that he has the information signature. This zero-knowledge proof includes the signer's identity information. Compared with the traditional confirmer signature algorithms, the improved scheme is simpler and more efficient, and has higher security.
Serge Abiteboul, Bogdan Cautis, Amos Fiat, T. Milo
The common assumption about digital signatures is that they disallow any kind of modification on signed data. However, a more flexible approach is often needed and has been advocated lately, one in which some restricted modifications may still occur, without invalidating the data. This is made possible by offering signatures which are homomorphic with respect to some operation on the message domain. Starting from the signature(s) of some data instance(s), computed by the data owner, anybody else can derive the signature corresponding to a new data instance, if obtained only via some accepted operation from the previous one(s). More, updated signatures should be indistinguishable from the ones computed by the data owner and this updating step should be applicable as many times as needed. This paper deals with the signing of insert-only collections, in which element insertions are accepted but no removals should occur. Newly inserted elements do not have to be signed or known by the initial signer. We propose two techniques: one which transposes the insert-only problem into a delete-only one (which is already solved), and another technique based on zero-knowledge proofs. We also give performance measures and discuss applications.
Blockchain technology has been gaining great interest from a variety of sectors including healthcare, supply chain, and cryptocurrencies. However, Blockchain suffers from a limited ability to scale (i.e., low throughput and high latency). Several solutions have been proposed to tackle this. In particular, sharding has proved to be one of the most promising solutions to Blockchain's scalability issue. Sharding can be divided into two major categories: (1) Sharding-based Proof-of-Work (PoW) Blockchain protocols, and (2) Sharding-based Proof-of-Stake (PoS) Blockchain protocols. The two categories achieve good performances (i.e., good throughput with a reasonable latency), but raise security issues. This article focuses on the second category. In this paper, we start by introducing the key components of sharding-based PoS Blockchain protocols. We then briefly introduce two consensus mechanisms, namely PoS and practical Byzantine Fault Tolerance (pBFT), and discuss their use and limitations in the context of sharding-based Blockchain protocols. Next, we provide a probabilistic model to analyze the security of these protocols. More specifically, we compute the probability of committing a faulty block and measure the security by computing the number of years to fail. We achieve a number of years to fail of approximately 4000 in a network of 4000 nodes, 10 shards, and a shard resiliency of 33%.
By applying the secret sharing system and the zero knowledge proof protocol,this paper presents a new time constraint delegation of the decryption scheme based on trust agent platforms,which solves the problem that the accessed peer cannot offer instant data when it is offline.This scheme carries out encryption and decryption by using ElGamal cryptography.It defines the delegating-agents protocol,the produce of the delegation-key protocol and the decryption protocol,thus implementing the cheat-resisted and quorum controlled time constraint delegation of decryption.And the new scheme is supplemented to settle the problems of the key being renewed dynamically,the agent being added or deleted and the agent's information being maintained.Compared with the previous time constraint delegation of the decryption scheme,it improves security,flexibility and efficiency.
In this paper, we introduce the concept of additive zero knowledge. Essentially, an additive proof can be considered as a proof system involving many provers and one verifier such that the statements of all the provers are proved simultaneously. Our model of additive proofs is presented using constructions of blind group identification, aggregate signatures and chained signatures. The security of our protocols relies on the difficulty of the underlying Diffie-Hellman problem in bilinear maps. As applications, we present a novel method to prevent spam.
In this paper we define a decentralized management mechanism for the dynamic coalition characteristic of virtual organization. We propose an identity-based threshold signature scheme for joint management. We also propose the policy mode for joint management, which uses role-based access control mechanism for authorization policies definition, and voting mechanism for authorization decision-making. Our solution can satisfy the dynamic coalition requirement of virtual organization, and also guarantee the autonomous characteristic of participant organizations and grid entities. Privacy preservation is also provided for grid entities to interact with authorized entities. Authorization revocation mechanism is taken into consideration in this paper. The experimental performance also shows the scalability of the solution.
Abstract. Micali, Rabin, and Kilian [9] recently introduced zero-knowledge sets and databases, in which a prover sets up a database by publishing a commitment, and then gives proofs about particular values. While an elegant and useful primitive, zero-knowledge databases do not offer any good way to perform updates. We explore the issue of updating zero-knowledge databases. We define and discuss transparent updates, which (1) allow holders of proofs that are still valid to update their proofs, but (2) otherwise maintain secrecy about the update. We give rigorous definitions for transparently updatable zero-knowledge databases, and give a practical construction based on the Chase et al [2] construction, assuming that verifiable random functions exist and that mercurial commitments exist, in the random oracle model. We also investigate the idea of updatable commitments, an attempt to make simple commitments transparently updatable. We define this new primitive and give a simple secure construction.
Omar Khadeer Hussain, Elizabeth Chang, Farookh Khadeer Hussain, Tharam S. Dillon ยท 5 authors
Risk is associated with almost every activity that is undertaken on a daily life. Risk associated with Trust, Security and Privacy. Risk is associated with transactions, businesses, information systems, environments, networks, partnerships, etc. Generally speaking, risk signifies the likelihood of financial losses, human casualties, business destruction and environmental damages. Risk indicator gives early warning to the party involved and helps avoid deserters. Until now, risk has been discussed extensively in the areas of investment, finance, health, environment, daily life activities and engineering. However, there is no systematic study of risk in Decentralised communication, which involves e-business, computer networks and service oriented environment. In this paper, we define risk associated with trusted communication in e-business and e-transactions; provide risk indicator calculations and basic application areas.
This paper proposes a computationally secure and fault-tolerant conference key distribution scheme, which only requires the authenticated and encrypted point-to-point channels between each server and each user. By the combined use of knowledge proof and verifiable secret sharing, the scheme has the properties of simple structure and high security. Analysis shows that every honest user of a conference can get a common key after the running of the protocol, even if a minority of the servers malfunction or misbehave. We also show that on the assumption of a Diffie-Hellman decisional problem, a passive adversary gets zero knowledge about the conference key, and the active adversary cannot impersonate someone successfully. Because the knowledge proof method we adopt is non-interactive, both operation and communication overheads are reduced, thus making the schemes very efficient.
A new threshold digital signature using the research result about the digital signature with zero knowledge proof was proposed in this paper. The security of this algorithm is based on large number of factorizations and security of RSA. The scheme doesnโt need to invert any elements in any structure, and then no algebraic extension is needed for any structure. It is useful for the information security.
Previous designated confirmer signature schemes were less e#cient because complex zero-knowledge proof employed in confirmation and disavowal protocol. In this paper, we propose a new e#cient signature scheme which is recipient-specific and confirmer-specific. The new scheme is transformed from ID-based chameleon signature and inherits its advantage in simplicity and e#ciency. The scheme's security relies on the underlying secure chameleon signature and public key encryption scheme. We also considers the case of confirmer as an adversary in security proof.
Zero-knowledge proof schemes of possessing a RSA digital signature are proposed. The schemes give a new method of preventing arbitrary propagation of digital signature. By which the prover does not need to give directly the signature of the message, but to give a zero-knowledge proof of possessing a digital signature. The schemes are the improvement of confirm signature, and is much simpler in practice and of significant feature that it does not need the third party to take part in the scheme. The schemes can be used in copyright protection.
Wanzong Peng, Tongliang Lu, Wenju Peng, Zhongpan Wang
File sharing, being the foundation of the Internet, has traditionally relied on a centralized service architecture resulting in significant maintenance costs. Moreover, due to the lack of an effective file management system, instances of sensitive information going out of control and loss of confidentiality in file sharing have occurred frequently. In order to address the difficulty of tamper detection and the lack of supervision in the entire process of file transfer in the current Internet environment, this paper designs a blockchain-based system architecture for secure sharing of electronic documents. An efficient blockchain model is used in our framework, and with the help of distributed storage system and asymmetric encryption technology, file sharing can be controlled, reliable and traceable in the transfer process. Referring to existing consensus mechanisms, e.g., Delegated Proof of Stake (DPoS) and Practical Byzantine Fault Tolerance (PBFT), we propose a new consensus for efficient and secure file sharing. Our experimental results show that our framework can maintain a higher throughput than existing schemes.
Cynthia Dwork, Moni Naor, Omer Reingold, Larry Stockmeyer
We prove that three apparently unrelated fundamental problems in distributed computing, cryptography, and complexity theory, are essentially the same problem. These three problems and brief descriptions of them follow. (1) The selective decommitment problem. An adversary is given commitments to a collection of messages, and the adversary can ask for some subset of the commitments to be opened. The question is whether seeing the decommitments to these open plaintexts allows the adversary to learn something unexpected about the plaintexts that are unopened. (2) The power of 3-round weak zero-knowledge arguments. The question is what can be proved in (a possibly weakened form of) zero-knowledge in a 3-round argument. In particular, is there a language outside of BPP that has a 3-round public-coin weak zero-knowledge argument? (3) The Fiat-Shamir methodology. This is a method for converting a 3-round public-coin argument (viewed as an identification scheme) to a 1-round signature scheme. The method requires what we call a "magic function" that the signer applies to the first-round message of the argument to obtain a second-round message (queries from the verifier). An open question here is whether every 3-round public-coin argument for a language outside of BPP has a magic function.It follows easily from definitions that if a 3-round public-coin argument system is zero-knowledge in the standard (fairly strong) sense, then it has no magic function. We define a weakening of zero-knowledge such that zero-knowledge โ no-magic-function still holds. For this weakened form of zero-knowledge, we give a partial converse: informally, if a 3-round public-coin argument system is not weakly zero-knowledge, then some form of magic is possible for this argument system. We obtain our definition of weak zero-knowledge by a sequence of weakenings of the standard definition, forming a hierarchy. Intermediate forms of zero-knowledge in this hierarchy are reasonable ones, and they may be useful in applications. Finally, we relate the selective decommitment problem to public-coin proof systems and arguments at an intermediate level of the hierarchy, and obtain several positive security results for selective decommitment.
Based on the zero-knowledge proof protocol a new forward-secure digital signature scheme is proposed. The scheme is proven to be forward secure based on the hardness of factoring,discrete logarithm and quadric remain problems in the random oracle model.
Sung Jun Park, TaeโHoon Kim, Dong Ho Won, Young Hwa An
We propose a new notion of an entrusted undeniable signature which is a variant of the undeniable signature. Also we propose a provably entrusted undeniable signature whose security can be proved. The proposed entrusted undeniable signature is a new type of undeniable signature in which the signer confirms his(her) signature to any verifier without the help of court but the verifier can't run the disavowal protocol in the undeniable signature which only court can run to solve the dispute later. The proposed scheme is constructed by a combination of the undeniable signature and zero-knowledge interactive proof system. The proposed provably entrusted undeniable signature is much the same as our entrusted undeniable signature but using the public key residue cryptosystem, which is polynomially secure, for the commitment scheme.