Demonstrably Secure Signature Scheme Resistant to k-Traitor Collusion Attack

Mobile devices now serve to pay for goods and services by means of the transmission of data, a system known as mobile payments. Mobile payment is receiving growing attention globally, from consumers to merchants, as an alternative to using cash, check, or credit cards. Most encryption techniques applied in mobile payment are based on traditional public key infrastructure. However, the traditional public key encryption algorithm has higher requirements for hardware, which is not suitable for mobile terminals of limited computing resources. In addition, these public key encryption algorithms are vulnerable to quantum computing attacks and the availability of practical quantum computer is approaching faster than previously believed. Since mobile payment is facing more and more security issues, how to complete the payment process effectively and securely becomes a problem urgently to be solved. In this paper, we firstly analyze the problem of the signature scheme for mobile payment and propose an improved signature scheme based on the Number Theory Research Unit (NTRU). The results of the experiment show that the proposed signature scheme is secure and efficient which can raise the speed and probability of generating reasonable signature value. Second, we introduce a new public key infrastructure NTRU-WPKI and design a third-party mobile payment model based on NTRU-WPKI to increase the efficiency and security. Finally, by doing the overall simulation, we prove that our model is highly effective and secure.

Deniable authentication allows a receiver to identify the source of a given message, but cannot prove the source of a given message to any third party. It can be employed in electronic voting (e-voting) systems, electronic tendering (e-tendering) systems and secure networks negotiation. These applications can be well realised in ad hoc networks. Therefore, deniable authentication is an essential security requirement for ad hoc networks. Aggregate deniable authentication is a method for combining n authenticator of n distinct messages from n distinct users into one single authenticator. This feature is very attractive in bandwidth-limited ad hoc networks. In this paper, we present an efficient certificateless aggregate deniable authentication protocol. Our protocol is based on certificateless public key cryptography that has neither the public key certificates management problem in traditional public key infrastructure (PKI) cryptography nor the key escrow problem in identity-based cryptography. The security of our protocol can be proven in the random oracle model under the bilinear Diffie-Hellman (BDH) and computational Diffie-Hellman (CDH) problems. In addition, our protocol adopts aggregate verification that can speed up the verification of authenticators. Our protocol is very suitable for ad hoc networks.

To design an efficient post-quantum linearly homomorphic signature scheme, using the pre-image sampling function, a lattice-based linearly homomorphic signature scheme over a binary field is proposed in this paper. Linear homomorphism is achieved through the homomorphism of the lattice-based hash function used in the proposed signature scheme. It is shown that the proposed scheme satisfies the privacy property. Based on the hardness of the short integer solution problem, the proposed scheme is unforgeable against the type 1 and type 2 adversaries in the random oracle model. Moreover, compared with a presented linearly homomorphic signature scheme in 2011, the proposed scheme has some advantages with respect to the public key size, signature length and computational cost.


 
 
 History of Seal and Printing Cultures Implications of the four important Chinese inventions, the compass, gun powder, papermaking, and printing, have far-reaching significance for human civilisation. The Chinese seal is intimately related to printing. Seals have the practical function of duplicating impressions of words or patterns. This process shares a very similar concept to printing on a small scale. Printing originated from the function of seals for making duplicated impressions, and for this reason Wang believes that seals constitute the prototype of printing. Seals in Traditional Commere Seals in certain Asian countries, such as Taiwan and Japan, play a vital role similar to that played by signatures in Western society. Particularly, the Chinese seal has been an integral part of Chinese heritage and culture. Wong states that seals usually symbolise tokens of promise in Chinese society. Ancient seals in their various forms have played a major role in information systems, in terms of authority, authentication, identification, certified proof, and authenticity, and have also been used for tamper-proofing, impression duplication, and branding purposes. To illustrate, clay sealing has been applied to folded documents to detect when sealed documents have been exposed or tampered with. Interestingly, one of the features of digital signature technology is also designed to achieve this purpose. Wong records that when the commodity economy began to develop and business transactions became more frequent, seals were used to prove that particular goods had been certified by customs. Moreover, when the goods were subject to tax by the government, seals were applied to the goods to prove the levy paid. Seals continue to be used in Chinese society as personal identification and in business transactions, official and legal documents, administrative warrants and charters. Paper-based Contract Signing with Seal Certificates In Taiwan and Japan, in certain circumstances, when two parties wish to formalise a contract, the seals of the two parties must be affixed to the contract. As Figure 1 illustrates, seal certificates are required to be attached to the signed and sealed contract for authentication as well as the statement of intent of a voluntary agreement in Taiwan. Figure 1. Example of a contract attached with the seal certificates A person can have more than one seal; however, only one seal at a time is allowed to be registered with a jurisdictional registration authority. The purpose of seal registration is to prevent seal forgery and to prove the identity of the seal owner. Namely, the seal registration process aims to associate the identity of the seal owner with the seal owner’s nominated seal, through attestation by a jurisdictional registration authority. Upon confirmation of the seal registration, the registration authority issues a seal certificate with both the seals of the registration authority and the registration authority executive. Digital Signatures for Electronic Commerce Handwritten signatures and tangible ink seals are highly impractical within the electronic commerce environment. However, the shift towards electronic commerce by both the public and private sector is an inevitable trend. ‘Trust’ in electronic commerce is developed through the use of ‘digital signatures’ in conjunction with a trustworthy environment. In principle, digital signatures are designed to simulate the functions of handwritten signatures and traditional seals for the purposes of authentication, data integrity, and non-repudiation within the electronic commerce environment. Various forms of Public Key Infrastructure (PKI) are employed to ensure the reliability of using digital signatures so as to ensure the integrity of the message. PKI does not, however, contribute in any way to the signatory’s ability to verify and approve the content of an electronic document prior to the affixation of his/her digital signature. Shortcomings of Digital Signature Scheme One of the primary problems with existing digital signatures is that a digital signature does not ’feel’ like, or resemble, a traditional seal or signature to the human observer; it does not have a recognisably individual or aesthetic quality. Historically, the authenticity of documents has always been verified by visual examination of the document. Often in legal proceedings, examination of both the affixed signature or seal as an integral part of the document will occur, as well as the detection of any possible modifications to the document. Yet, the current digital signature regime overlooks the importance of this sense of visualisation. Currently, digital signatures, such as the OpenPGP (Pretty Good Privacy) digital signature, are appended to an electronic document as a long, incomprehensible string of arbitrary characters. As shown in Figure 2, this offers no sense of identity or ownership by simple visual inspection. Figure 2. Example of a PGP signature To add to this confusion for the user, a digital signature will be different each time the user applies it. The usual digital signature is formed as an amalgam of the contents of the digital document and the user’s private key, meaning that a digital signature attached to an electronic document will vary with each document. This again represents a departure from the traditional use of the term ‘signature’. A digital signature application generates its output by firstly applying a hash algorithm over the contents of the digital document and then encrypting that hash output value using the user’s private cryptographic key of the normal dual-key pair provided by the Public Key cryptography systems. Therefore, digital signatures are not like traditional signatures which an individual can identify as being uniquely theirs, or as a recognisable identity attributable to an individual entity. New Visualised Digital Signature Scheme Liu et al. have developed the visualised digital signature scheme to enhance existing digital signature schemes through visualisation; namely, this scheme makes the intangible digital signature virtually tangible. Liu et al.’s work employs the visualised digital signature scheme with the aim of developing visualised signing and verification in electronic situations. The visualised digital signature scheme is sustained by the digital certificate containing both the certificate issuer’s and potential signer’s seal images. This thereby facilitates verification of a signer’s seal by reference to the appropriate certificate. The mechanism of ensuring the integrity and authenticity of seal images is to incorporate the signer’s seal image into an X.509 v3 certificate, as outlined in RFC 3280. Thus, visualised digital signature applications will be able to accept the visualised digital certificate for use. The data structure format of the visualised digital certificate is detailed in Liu. The visualised signing and verification processes are intended to simulate traditional signing techniques incorporating visualisation. When the signer is signing the document, the user interface of the electronic contracting application should allow the signer to insert the seal from the seal image file location into the document. After the seal image object is embedded in the document, the document is referred to as a ’visually sealed’ document. The sealed document is ready to be submitted to the digital signing process, to be transmitted with the signer’s digital certificate to the other party for verification. The visualised signature verification process is analogous to the traditional, sealed paper-based document with the seal certificate attached for verification. In history, documents have always required visual stimulus for verification, which highlights the need for visual stimulus evidence to rapidly facilitate verification. The user interface of the electronic contracting application should display the visually sealed document together with the associated digital certificate for human verification. The verifier immediately perceives the claimed signer’s seal on the document, particularly when the signer’s seal is recognisable to the verifier. This would be the case particularity where regular business transactions between parties occur. Significantly, having both the issuing CA’s and the signer’s seal images on the digital certificate instils confidence that the signer’s public key is attested to by the CA, as shown in Figure 3. This is unlike the current digital signature verification process which presents long, meaningless strings to the verifier. Figure 3. Example of a new digital certificate presentation Conclusions Seals have a long history accompanying the civilisation of mankind. In particular, certain business documents and government communities within seal-culture societies still require the imprints of the participating entities. Inevitably, the use of modern technologies will replace traditional seals and handwritten signatures. Many involved in implementing electronic government services and electronic commerce care little about the absence of imprints and/or signatures; however, there is concern that the population may experience difficulty in adapting to a new electronic commerce system where traditional practices have become obsolete. The purpose of the visualised digital signature scheme is to explore enhancements to existing digital signature schemes through the integration of culturally relevant features. This article highlights the experience of the use and development of Chinese seals, particularly in visualised seals used in a recognition process. Importantly, seals in their various forms have played a major role in information systems for thousands of years. In the advent of the electronic commerce, seal cultures still remain in the d

Vehicular ad-hoc networking can provide efficient traffic information, emergency warning, alert messages and infotainment dissemination. It takes a vital role in safety fields such as defense system, traffic system, etc. Even though, some advanced Public Key Infrastructure and digital signature method was used for security, intrusion detection is an inevitable challenge in networks. Prevention and detection of malicious vehicle from jeopardizing the safety of the other vehicle is focused in this paper by using region-based FBB (Flooding-Bilinear-Bloom Filter) authentication protocol. Authentication is performed in any PKI (Public Key Infrastructure) system by checking if the certificate of the sender is included in the CRL (Certificate Revocation List) and verifying the authenticity and checking the sign of the sender. Bilinear pairing method is used to create an anonymous Id for each vehicle. The CRL checking process has been done using Bloom Filter method which avoids false negative. CRL can be passed between vehicles by bi-directional flooding method which avoids network congestion. This paper focuses mainly the CRL dissemination using the bi-directional flooding method. It replaces the time-consuming CRL Checking process. It reduces message loss ratio by using fast revocation checking and CRL updating method as well as it needs very less memory space compared to other methods.

Signcryption is a useful cryptographic primitive which simultaneously performs encryption and signature with cost less than the signature-then-encryption approach. Identity-based signcryption (IBSC) eliminates the complicated management of certificates in signcryption schemes in the traditional public-key infrastructure (PKI) setting. Most IBSC schemes are constructed in the random oracle model, while it is unknown how to instantiate a really ``random oracle in the real world. By exploiting Boneh et al.'s strongly unforgeable signature and Paterson et al.'s identity-based signature, this paper proposes a new IBSC scheme in the standard model. It is proven that our IBSC scheme satisfies semantic security and strong unforgeability under the bilinear decision Diffie-Hellman (BDDH) assumption. The proofs do not rely on random oracles. Performance analysis shows that our scheme is also efficient and practical.

The massive growth of electronic commerce on the Internet heightens concerns over the lack of meaningful certificate management. One issue limiting the availability of such services is the absence of scalable certificate revocation. The use of certificate revocation lists (CRLs) to convey revocation state in public key infrastructures has long been the subject of debate. Centrally, opponents of the technology attribute a range of semantic and technical limitations to CRLs. In this paper, we consider arguments advising against the use of CRLs made principally by Rivest in his paper “Can we eliminate certificate revocation lists?” [1]. Specifically, the assumptions and environments on which these arguments are based are separated from those features inherent to CRLs. We analyze the requirements and potential solutions for three distinct PKI environments. The fundamental tradeoffs between revocation technologies are identified. Prom the case study analysis we show how, in some environments, CRLs are the most efficient vehicle for distributing revocation state. The lessons learned from our case studies are applied to a realistic PKI environment. The result, revocation on demand, is a CRL based mechanism providing timely revocation information.

Kakvi and Kiltz (EUROCRYPT'12) proposed the first tight security reduction for RSA full domain hash signature scheme (RSA-FDH) with public exponent e < N1/4 in the random oracle (RO) model, and they left an open problem which called for a tightly secure RSA-FDH for N1/4 < e < N. In this paper, we consider the improved RSA (iRSA) trapdoor functions, introduced by Cao (Science in China'01), are functions that the security can be strictly proved to be equivalent to the factoring. We show that iRSA-FDH has a tight security reduction for e < N. Technically we construct iRSA lossy trapdoor functions, and then we apply the lossiness of the iRSA trapdoor functions to obtain tight security reductions for iRSA-FDH in the RO model. Finally, we propose a tightly secure blind signature scheme based on our iRSA lossy trapdoor functions in the RO model.

This paper develops a numerical procedure to accelerate the convergence of the Favre-averaged non-linear harmonic (FNLH) method. The scheme provides a unified mathematical framework for solving the sparse linear systems formed by the mean flow and the time-linearized harmonic flows of FNLH in an explicit or implicit fashion. The approach explores the similarity of the sparse linear systems of FNLH and leads to a memory-efficient procedure, so that its memory consumption does not depend on the number of harmonics to compute. The proposed method has been implemented in the industrial computational fluid dynamics solver Hydra. Three test cases are used to conduct a comparative study of explicit and implicit schemes in terms of convergence, computational efficiency, and memory consumption. Comparisons show that the implicit scheme yields better convergence than the explicit scheme and is also roughly 7–10 times more computationally efficient than the explicit scheme with four levels of multigrid. Furthermore, the implicit scheme consumes only approximately 50% of the memory required by the explicit scheme with four levels of multigrid. Compared with the full-annulus unsteady Reynolds-averaged Navier–Stokes simulations, the implicit scheme produces comparable results to URANS with computational time and memory consumption that are two orders of magnitude smaller.

Recently, Boneh et al. proposed the concept of an aggregate signature, introduced security models for such signatures, and also presented some applications. An aggregate signature scheme is a digital signature that supports aggregation: Given n signatures on n distinct messages from n distinct users, it is possible to aggregate all these signatures into a single short signature. This single signature, along with the n original messages will convince verifiers that the n users did indeed sign the n original messages respectively, i.e., user i signed message Mi for i = 1, ..., n. In this paper, however, we find that their security model has some defects. The capacity that the adversaries possess was constrained according to the standard security definition of signatures. We propose an improvement of the Boneh’s scheme by presenting a new security model and giving a formal proof in random oracle model.

An aggregate signature (AS) scheme combines multiple signatures which is generated by many different users into a single one. This feature is very beneficial for diminishing storage cost, bandwidth and verification cost. Many previous attempts have been made for designing AS schemes, while the former security models have not clearly addressed coalition attacks, and most of the existing AS schemes cannot resist these kinds of attacks. In this study, the authors provide a modified security model of certificateless AS (CLAS) schemes and then give a new CLAS scheme. The security of their present scheme can be rigorously proved based on the computational Diffie-Hellman assumption in the random oracle model. Furthermore, their scheme can resist such coalition attacks, i.e. an AS in their scheme is valid iff all single signatures used to generate the AS are valid.

Vehicular ad hoc network (VANET) plays a vital role in the intelligent transportation system (ITS). When a vehicle receives a message through network, the CRL (certificate revocation list) checking process will operate before certificate and signature verification. After successful authentication, a CRL list is created based on authentication. This CRL is used to verify whether a vehicle node can be permitted for communication in the VANET network. But when using CRL, a huge amount of storage space and checking time is needed. So we proposed a method without the CRL list. It mentions a key management list to overcome large storage space and checking time. Even it reduced the access delay. For access permission we can do an authentication system based digital novel signature authentication (DNSA) for each vehicle in the VANET with the RSU unit or with other participant node vehicles in the communication as per the topology. We can perform an efficient and secured communication in VANET.

Certificate-based cryptosystem can eliminate the private key escrow problem inherent in the identity-based cryptosystem and can simplify the costly certificate management in the traditional public key cryptosystem. In 2016, Lu et al. raised an open problem of whether the certificate-based signature (CBS) scheme can be proved secure against the malicious-but-passive certifier attack. In this study, the authors try to solve this problem. They give an enhanced security model of the CBS scheme which can resist the malicious-but-passive certifier attack. Then they propose a concrete CBS scheme in the standard model by using bilinear pairings. They prove the scheme to be secure in the enhanced security model under the Squ-CDH assumption. In this way, the authors give an affirmative answer to the above open problem. Finally, the authors evaluate the efficiency of the scheme which shows it to be practical. In addition, they find that malicious-but-passive certifier security cannot coexist with super adversary security in a CBS scheme in the standard model.

&lt;p style='text-indent:20px;'&gt;&lt;b&gt;I&lt;/b&gt;dentity-&lt;b&gt;B&lt;/b&gt;ased &lt;b&gt;B&lt;/b&gt;roadcast &lt;b&gt;E&lt;/b&gt;ncryption (&lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$\textsf{IBBE}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;) is a novel concept that can efficiently and securely transmit confidential content to a group of authorized users without the traditional &lt;b&gt;P&lt;/b&gt;ublic-&lt;b&gt;K&lt;/b&gt;ey &lt;b&gt;I&lt;/b&gt;nfrastructure (&lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$\textsf{PKI}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;). After carefully exploring these areas, we have observed that none of the existing works have adopted the quantum-attack resistant cryptographic machinery &lt;b&gt;M&lt;/b&gt;ultivariate &lt;b&gt;P&lt;/b&gt;ublic-&lt;b&gt;K&lt;/b&gt;ey &lt;b&gt;C&lt;/b&gt;ryptography (&lt;inline-formula&gt;&lt;tex-math id="M3"&gt;\begin{document}$\textsf{MPKC}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;) with provable security. We are the &lt;i&gt;first&lt;/i&gt; to design a quantum-safe &lt;inline-formula&gt;&lt;tex-math id="M4"&gt;\begin{document}$\textsf{IBBE}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; that solely relies on the &lt;inline-formula&gt;&lt;tex-math id="M5"&gt;\begin{document}$\textsf{MPKC}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; framework. Our proposed protocol has achieved &lt;inline-formula&gt;&lt;tex-math id="M6"&gt;\begin{document}$ \mathcal{O}(n) $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;-size communication bandwidth and &lt;inline-formula&gt;&lt;tex-math id="M7"&gt;\begin{document}$ {n^3}\cdot\mathcal{O}\big(\max\big\{N, {\delta}^4\big\}\big) $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;-size overhead storage without any security breach. Here, &lt;inline-formula&gt;&lt;tex-math id="M8"&gt;\begin{document}$ n $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; is the number of variables for each multivariate polynomial, &lt;inline-formula&gt;&lt;tex-math id="M9"&gt;\begin{document}$ N $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; represents the total number of system users, and &lt;inline-formula&gt;&lt;tex-math id="M10"&gt;\begin{document}$ \delta $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; denotes a positive fixed-length. More positively, our design has achieved the &lt;i&gt;adaptive&lt;/i&gt; &lt;b&gt;IND&lt;/b&gt;istinguishable &lt;b&gt;C&lt;/b&gt;hosen-&lt;b&gt;C&lt;/b&gt;iphertext &lt;b&gt;A&lt;/b&gt;ttack (&lt;inline-formula&gt;&lt;tex-math id="M11"&gt;\begin{document}$\textsf{IND-CCA}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;) security in the &lt;b&gt;R&lt;/b&gt;andom &lt;b&gt;O&lt;/b&gt;racle &lt;b&gt;M&lt;/b&gt;odel (&lt;inline-formula&gt;&lt;tex-math id="M12"&gt;\begin{document}$\textsf{ROM}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;) under the hardness of standard &lt;b&gt;M&lt;/b&gt;ultivariate &lt;b&gt;Q&lt;/b&gt;uadratic (&lt;inline-formula&gt;&lt;tex-math id="M13"&gt;\begin{document}$\textsf{MQ}$\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;) problem. We emphasize that our system can also be immune against collusion attacks where several users come together to create an illicit decryption box.&lt;/p&gt;

The notion of certificateless cryptography is aimed to eliminate the use of certificates in traditional public key cryptography and also to solve the key-escrow problem in identity-based cryptography. Many kinds of security models have been designed for certificateless cryptography and many new schemes have been introduced based on the correspondence of the security models. In generally speaking, a stronger security model can ensure a certificateless cryptosystem with a higher security level, but a realistic model can lead to a more efficient scheme. In this paper, we focus on the efficiency of a certificateless signature (CLS) scheme and introduce an efficient CLS scheme with short signature size. On one hand, the security of the scheme is based on a realistic model. In this model, an adversary is not allowed to get any valid signature under false public keys. On the other hand, our scheme is as efficient as BLS short signature scheme in both communication and computation and, therefore, turns out to be more efficient than other CLS schemes proposed so far. We provide a rigorous security proof of our scheme in the random oracle model. The security of our scheme is based on the k-CAA hard problem and a new discovered hard problem, namely the modified k-CAA problem. Our scheme can be applied to systems where signatures are typed in by human or systems with low-bandwidth channels and/or low-computation power.