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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]

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]

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]

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]

E-cash system can guarantee the anonymity of the user, but it also can be misused illegally. So the idea of fair E-cash was introduced, i.e., the anonymity of the user can be revoked when a crime is involved in fair E-cash system. However, it is still an unsolved problem to design a practical and efficient fair E-cash scheme, since there are some problems of the impracticality or the incompleteness in the tracing design of existing schemes. First we discuss the principal reasons of it. The reason of impractical tracing is that many schemes have respective unsolved problems in designing the practical tracing. We solve one kind of the problems, then present the practical tracings in various situations, including the bank's double-spending tracing without the trusted third party (TTP), the TTP's unconditional tracing and the bank's loss-coin tracing without TTP, which we call complete tracing. For some schemes, the reason of incomplete tracing is that the unsolved efficiency problems result in the incomplete design of tracing, whereas for other schemes, the reason of incomplete tracing is that the unconditional tracing and the anonymous spending are contradicting properties of E-cash. Considering that, the TTP can be divided into multiple parties, and the TTP is also removable in our system. Moreover, for solving the efficiency problem of practical tracing, we use a nested structure of signature of knowledge in payment protocol, which is proved to be a secure application. Then we provide the detailed security proofs of all security properties of our E-cash scheme and analyze our system efficiency and system functions comparing with the recent schemes. [ABSTRACT FROM AUTHOR]

Blind signatures allow users to obtain signatures on messages hidden from the signer; moreover, the signer cannot link the resulting message/signature pair to the signing session. This paper presents blind signature schemes, in which the number of interactions between the user and the signer is minimal and whose blind signatures are short. Our schemes are defined over bilinear groups and are proved secure in the common-reference-string model without random oracles and under standard assumptions: CDH and the decision-linear assumption. (We also give variants over asymmetric groups based on similar assumptions.) The blind signatures are Waters signatures, which consist of 2 group elements.Moreover, we instantiate partially blind signatures, where the message consists of a part hidden from the signer and a commonly known public part, and schemes achieving perfect blindness. We propose new variants of blind signatures, such as signer-friendly partially blind signatures, where the public part can be chosen by the signer without prior agreement, 3-party blind signatures, as well as blind signatures on multiple aggregated messages provided by independent sources.We also extend Waters signatures to non-binary alphabets by proving a new result on the underlying hash function. [ABSTRACT FROM AUTHOR]

Proxy blind signature is an important cryptographic primitive and plays an essential role in construction of the electronic cash (e-cash). Recently, Tan (2001, An offline electronic cash scheme based on proxy blind signature. Comput. J., 54, 505–512) proposed a new proxy blind signature scheme and applied it to electronic cash. The scheme was claimed as being provably secure under the Discrete Log assumption, DBDH assumption and Chosen–Target CDH assumption in the random oracle model. In this paper, we show that Tan's proxy blind signature scheme is insecure by demonstrating several attacks in which a malicious original signer can forge both valid proxy signature keys of arbitrary proxy signers and a proxy blind signature on an arbitrary message with respect to any proxy signer directly. We also discuss some weaknesses in the e-cash scheme proposed by Tan. [ABSTRACT FROM AUTHOR]

This paper has shows the application of the basic types of payment transactions and electronic means of payment. Collecting and comparing a number of data, various types of electronic payment transactions have been analyzed in the demanding worldwide markets, with emphasis on maritime transport. Special emphasis has been put on the EU regulative that aims to define and gradually introduce the electronic money so the new market instabilities would be avoided. Based on the processing of available data, classifying certain payment transactions, using electronic means of payment, emphasizing the role of electronic money, as well as applications in maritime transport, one possible model of grouping the e-business transactions within maritime industry is proposed. [ABSTRACT FROM AUTHOR]

In this paper, we propose a refined proxy deposit protocol based on the scheme proposed by Yu and Lei, A proxy deposit protocol for e-cash systems, in: ICCSA2001, 2001, p. 289 and implement two mathematic models (for ElGamal and RSA scheme) base on the scheme of Chen et al., refined proxy deposit protocol for e-cash systems, in: ICCSA2002, 2002, p. 141. And in consideration of the relationship in most typical e-cash scheme (various studies), a merchant must maintain an account at the issuer for depositing the received e-cash from customers. Since there will be a lot of issuers in the real world, each merchant must maintain an account at each issuer for depositing all kinds of e-cash. In order to reduce the onus of the merchants, the concept of deposit-delegation protocol will be introduced in this paper such that a merchant only has to maintain an account at its trading bank (as an acquirer) and delegates all deposit business to it. [Copyright &y& Elsevier]

We propose a practical multi-authority e-cash scheme that satisfies anonymity, security and verifiability. By means of our proposed scheme, the issue of e-coins is controlled by several issuers. Customers can request e-coins from several issuers, who represent a bank, on the current available issuers list according to the Internet condition. [Copyright &y& Elsevier]