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In this paper, we propose a new cryptographic primitive, called multiple blind signature (MBS), which is designed based on the integration of both normal blind signature scheme and dual signature. The major difference between a normal blind signature and an MBS is that using a normal blind signature, only one message, |$m$|⁠ , can be verified, but using an MBS, any subset, |${M}^{\prime }$|⁠ , of multiple messages in a set, |$M$|⁠ , where |${M}^{\prime}{\subseteq} M$|⁠ , can be verified. With this additional property, we will show that MBS is especially suitable for e-voting and e-cash applications. In other words, we classify these processes in two applications into two phases, on-line and off-line phases. One unique property of this design is that most time-consuming computation and interaction can be performed in advance in off-line phase. There is no cost of computation and interaction in the online phase. [ABSTRACT FROM AUTHOR]

Linkable ring signatures is a useful cryptographic tool for constructing applications such as ones relative to electronic voting (e-voting), digital cashes (e-cashes) as well as cloud computing. Equipped with linkable ring signatures, e-voting, e-cash systems can simultaneously enjoy the privacy and the unreusability properties thanks to the anonymity and the linkability of linkable ring signatures. Likewise, cloud servers can enjoy a privacy-preserving ability, a flexible access control and an efficient security management with linkable ring signatures. Moreover, linkable ring signatures built in the identity-based setting would help to remove the expense of using the conventional public key infrastructure and also could be applied to the user management. This primitive hence would be suitable for huge-scale applications. In this paper, we present the first identity-based linkable ring signatures (IdLRS) in both integer lattice and ideal lattice setting. The proposed IdLRS is proved secure in the random oracle model and based on the hardness of the short integer solution and ring short integer solution assumption. We also implement the proposed idLRS as a proof of concept and then do some experiments to evaluate the running times and the sizes.

This study was commissioned to investigate the level of risk and Barriers associated with mobile money transactions in Ghana. It seeked to assess the level of risk perception among mobile money users and merchants. In addition to the above, the paper examined behaviour and attitudes exhibited by customers and merchants during mobile money transactions. This was to help in ascertaining whether or not both parties are being susceptible to high risk or not. The empirical evidence showed that, mobile money transactions have become the most popular and preferred method of sending and receiving payments in Africa since the vast majority of the Continent’s population are rural dwellers with Ghana not being an exception. The population for the study was customers and merchants of the MTN brand of mobile money from which five hundred and fifty (550) respondents were sampled for the study. The methodology used was quantitative where primary data was sort through administration of questionnaire within the Sekondi-Takoradi Metropolis. The paper discovered a higher-level patronage of mobile money among respondents. It emerged that, there were eminent risks associated with mobile money operations although the growth prospects appeared to be greater. [ABSTRACT FROM AUTHOR]

The author by analyzing theoretical ideas put forward b y A. Yu. Simanovskiy in the research ‘Concerning Economic Nature of Crypto-Currency’, which was published in the journal “Issues of Economics’ provides his own opinion concerning whether currency (including crypto-currency) can have economic nature. This question is not rhetoric and has nothing to do with casuistry. It is essential, principle and touches upon problems dealing with national security. On the basis of system-functional analysis and achievements of modern theory of money and using its fundamental provisions the author considers the content of money in dialectic unity of form transformation (material, money, paper, electronic) and spheres (social – money as a symbol; economic – bank notes; political and legal – monetary units) of their being. It is shown that currency, especially crypto-currency cannot have economic nature. In this connection the author studying the process of historical transformation of international monetary systems with regard to achievements of finance, technical and social engineering aimed at creation of ‘digital gold’ thinks that the social and economic model of the future international monetary system has been tested already.

Based on ethnographically-inspired research in Japan, we report on people's experiences using digital money payment systems that use Sony's FeliCa near-field communication smartcard technology. As an example of ubiquitous computing in the here and now, the adoption of digital money is found to be messy and contingent, shot through with cultural and social factors that do not hinder this adoption but rather constitute its specific character. Adoption is strongly tied to Japanese conceptions of the aesthetic and moral virtue of smooth flow and avoidance of commotion, as well as the excitement at winning something for nothing. Implications for design of mobile payment systems stress the need to produce open-ended platforms that can serve as the vehicle for multiple meanings and experiences without foreclosing such possibilities in the name of efficiency. Copyright 2008 ACM.

Based on ethnographically-inspired research in Japan, we report on people's experiences using digital money payment systems that use Sony's FeliCa near-field communication smartcard technology. As an example of ubiquitous computing in the here and now, the adoption of digital money is found to be messy and contingent, shot through with cultural and social factors that do not hinder this adoption but rather constitute its specific character. Adoption is strongly tied to Japanese conceptions of the aesthetic and moral virtue of smooth flow and avoidance of commotion, as well as the excitement at winning something for nothing. Implications for design of mobile payment systems stress the need to produce open-ended platforms that can serve as the vehicle for multiple meanings and experiences without foreclosing such possibilities in the name of efficiency. Copyright 2008 ACM.

In our previous paper we presented an offline e-cash system with observers. We have shown that the proposed system satisfies basic requirements for e-cash schemes. We also covered such security issues as chosen message attack resistance and forgery of protocols data. However, in that paper we focused more on the system itself, rather than its analysis. Hence, here we present cryptanalysis of our system. We aim to prove that existential forgery of data is not possible due to complexity of the discrete logarithm problem. Furthermore, we perform the analysis of trustworthiness of the system using the so-called BAN logic. Also, we consider effectivity of the proposed e-cash system in observers with limited computational resources. [ABSTRACT FROM AUTHOR]

Increasing digitisation, developments in electronic payment technology -- especially cryptocurrencies -- and the declining use of paper cash are prompting discussions regarding the possibility of central banks launching electronic cash (e-cash). This paper discusses the expectations that e-cash would need to meet, from a user perspective, and argues that e-cash would need to have more in common with modern account-based electronic and mobile account payments than with traditional cash. Were central banks to launch e-cash, they would be in direct competition with private payment services. A successful e-cash service would therefore require a competitive edge over private electronic payment services. This would create a risk of market distortion for both payments and deposit services. Regulatory issues such as knowyour- customer requirements and account/transaction liabilities would play a major role in e-cash services. Central bank e-cash would have to fulfil the basic payment instrument requirements of a sufficiently large segment of the payments market. [ABSTRACT FROM AUTHOR]

A simple mobile e-cash system with observers satisfying e-cash divisibility, partial anonymity, off-line payment, transferability and double-spending prevention requirements is presented. The proposed e-cash system is based on two well-known cryptographic primitives, namely ElGamal signature along with Schnorr identification protocols. Therefore, it can be considered simple in the sense of implementation and security considerations. The traditional and elliptic curve realizations of e-money system are presented. The system employs observers, i.e. cryptographic bank chips implemented in customer's payment device (e.g. smart phone) in order to avoid the increase in the size of transferred e-cash data, which is a major flaw of most divisible, anonymous, off-line and transferable e-cash systems. The security of the proposed e-money system is based on discrete logarithm problems in cyclic and elliptic curve groups. The system's security against chosen message attack is provided. [ABSTRACT FROM AUTHOR]

Certificateless public key cryptography (CL-PKC) is a new benchmark in modern cryptography. It not only simplifies the certificate management problem of PKC, but also avoids the key escrow problem of the identity based cryptosystem (ID-PKC). In this article, we propose a certificateless blind signature protocol which is based on elliptic curve cryptography (CLB-ECC). The scheme is suitable for the wireless communication environment because of smaller parameter size. The proposed scheme is proven to be secure against attacks by two different kinds of adversaries. CLB-ECC is efficient in terms of computation compared to the other existing conventional schemes. CLB-ECC can withstand forgery attack, key only attack, and known message attack. An e-cash framework, which is based on CLB-ECC, has also been proposed. As a result, the proposed CLB-ECC scheme seems to be more effective for applying to real life applications like e-shopping, e-voting, etc., in handheld devices. [ABSTRACT FROM AUTHOR]

Trading card games (TCG) differ from traditional card games mainly because the cards employed are not shared among players in a match. Instead, users play with the cards they own (e.g., purchased or traded with other players), which corresponds to a subset of all cards produced by the game provider. Even though most computer-based TCGs rely on a trusted third-party (TTP) for preventing cheating during trades, allowing them to securely do so without such entity remains a challenging task. Potential solutions are related to e-cash protocols, but, unlike the latter, TCGs allow users to play with the cards under their possession, not only to pass those cards over. In this work, we present the security requirements of TCGs and how they relate to e-cash. We then propose a concrete, TTP-free protocol for anonymously trading cards, using as basis a secure transferable e-cash protocol. [ABSTRACT FROM PUBLISHER]

Abstract In e-Cash, signer must sign a value without seeing it's content directly. Traditional RSA based approaches encounter a fundamental problem named Chosen Text Attack. The main aim of this research is to propose an approach to overcome such attack. Although using random values in signature apparently raise computational complexity, it guaranties security. In this paper, computational complexity of the proposed approach has been studied and its superiority compared to the regular blind signature approach of Fan et al. has been approved. Resistance against forgery, which is the main objective of the new signature approach has also been studied and approved.

This paper improved Au et al' s e-cash system with anonymous user suspension. To achieve improvement in performance and security, this paper extended the EPID system of Brickell et al. by incorporating the technique of self-blindable credential and hatch zero-knowledge proof. Moreover, the construction of the new system adopted the approach of Xi et al., i. e., to divide system time into small periods and to issue passports to users who have not been revoked. In the revised system, users should obtain passports through the pre-computation stage before withdrawing e-coins. After that, the computation and communication cost of all the parties in the withdrawal and payment protocols are constant. In addition, the new system achieves higher level of balance and exculpability in game-based model. [ABSTRACT FROM AUTHOR]

The blind signature scheme permits the user to acquire a signature from the signer; however, the message and the final signature are unknown to the signer. In any partially blind signature (PBS) scheme, the signer is allowed to explicitly incorporate the common information in the signature based on some agreements with the user, however, without compromising the blindness property. Recently, many PBS schemes have been designed by using either certificate authority-based public infrastructure (CA-PKI) or bilinear pairing along with map-to-point hash function. The CA-PKI-based PBS scheme needs huge computation and storage to keep the public keys and the certificates. Note that the pairing and map-to-point hash function are costly operations. Thus, the ID-PBS scheme without pairing is more appropriate for real environments and this paper has come up with an efficient pairing-free ID-PBS scheme. The designed scheme is rigorously examined in the random oracle model, which substantiated that it is provably secure. We also proposed an online e-cash system using our ID-PBS scheme, in which the bank agreed on a common piece of information with the customer and blindly signed some messages. Note that our e-cash system has the properties of unforgeability, unlinkability, non-deniability and prevention of double-spending of e-cash. [ABSTRACT FROM AUTHOR]