A fair payment system with online anonymous transfer

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2007.Includes bibliographical references (p. 26-27).Physical cash can be anonymously transfered. Transferability is a desirable property because it allows for flexible, private commerce where neither the seller nor the buyer must identify themselves to the bank. In some cases, however, anonymity can be abused and lead to problems such as blackmail and money laundering. In 1996, Camenisch, Piveteau, and Stadler introduced the concept of fairness for (non-transferable) ECash, where a trusted authority can revoke the anonymity of certain transactions as needed. To our knowledge, no current ECash system supports both anonymous transfer and fairness. We have designed and implemented such a system. Also, we formally describe a set of desirable properties for ECash systems and prove that our system meets all of these properties under the Strong RSA assumption and the Decisional Diffie-Hellman assumption in the random oracle model. Furthermore, we provide extensions for our system that could allow it to deal with offline payments and micropayments. Our system has been implemented in java. Tests have shown that it performs and scales well, as expected.by Bin D. Vo.M.Eng

Individual Risk Management for Digital Payment Systems

Despite existing security standards and security technologies, such as secure hardware, gaps between users’ demand for security and the security offered by a payment system can still remain. These security gaps imply risks for users. In this paper, we introduce a framework for the management of those risks. As a result, we present an instrument enabling users to evaluate eventual risks related with digital payment systems and to handle these risks with technical and economic instruments.Payment Systems, Digital Money

Hang With Your Buddies to Resist Intersection Attacks

Some anonymity schemes might in principle protect users from pervasive network surveillance - but only if all messages are independent and unlinkable. Users in practice often need pseudonymity - sending messages intentionally linkable to each other but not to the sender - but pseudonymity in dynamic networks exposes users to intersection attacks. We present Buddies, the first systematic design for intersection attack resistance in practical anonymity systems. Buddies groups users dynamically into buddy sets, controlling message transmission to make buddies within a set behaviorally indistinguishable under traffic analysis. To manage the inevitable tradeoffs between anonymity guarantees and communication responsiveness, Buddies enables users to select independent attack mitigation policies for each pseudonym. Using trace-based simulations and a working prototype, we find that Buddies can guarantee non-trivial anonymity set sizes in realistic chat/microblogging scenarios, for both short-lived and long-lived pseudonyms.Comment: 15 pages, 8 figure

Banking the unbanked using prepaid platforms and mobile telephones in the United States

The rapid growth of mobile phone usage and the continuous rise in wireless coverage fuel the expectations that access to financial services trough mobile phones could transform the way financial services are provided. The emergence of new and more efficient business models, can potentially resolve supply inefficiencies that explain the large unbanked population that exists in the USA, much larger than in most developed countries. Nearly 40 million US households (approximately 73 million people) are financially underserved (CFSI, 2007), of which 15 million households (approximately 28 million people) are totally unbanked. This problem is explained by the non adequacy of the value proposals offered by financial institutions to the demands of the US customers. The areas of poor alignment refer mostly to the design of products and the marketing and distribution networks used. To resolve these misalignments, this paper will argue that business models based on prepaid cards as products and mobile phones as transactional and distribution channels could be used in order to close the supply gap. We will call the business model proposed based on prepaid products and mobile phones mobile banking, since these two elements are the basis of the business model used companies such as Smart Money and G-Cash in the Phillipines, Wizzit in South Africa and M-Pesa in Kenya.prepaid platform; unbanked; financial services; mobile phones; prepaid cards;

Development of a certificate less digital signature scheme & implementation in e-cash system

Today’s wireless communication systems having limited computational resources and communication bandwidth find certificate less public-key cryptosystems very attractive and vital to their operations in the sense that they help in reducing a significant amount of data load on the network. To eliminate the need of public key digital certificates Shamir proposed ID based cryptosystems in which the user’s identity (e.g. name or email id) is used as the public key. However this method had a major drawback of the key escrow problem as a result of which certificate less digital signature (CDS) came into light. The main idea behind CDS is that there’s a private key generator (PKG) which generates a partial private key for the user .Then using that key and some of its own private information the user computes its actual private key. PKG’s public parameters and the user’s private key together calculate the user’s public key. Harn, Ren and Lin in 2008 proposed a CDS model which consisted of four generic modules namely PKG, user key generation, signature generation and verification. In this paper, we propose an improvement of the aforesaid CDS scheme in terms of time complexity and signature length and implement the new scheme in an e-cash model proposed by Popescu and Oros. Performance analysis of both the schemes has been carried out in details

A Scalable Architecture for Electronic Payments

We present a scalable architecture for electronic retail payments via central bank digital currency and offer a solution to the perceived conflict between robust regulatory oversight and consumer affordances such as privacy and control. Our architecture combines existing work in payment systems and digital currency with a new approach to digital asset design for managing unforgeable, stateful, and oblivious assets without relying on either a central authority or a monolithic consensus system. Regulated financial institutions have a role in every transaction, and the consumer affordances are achieved through the use of non-custodial wallets that unlink the sender from the recipient in the transaction channel. This approach is fully compatible with the existing two-tiered banking system and can complement and extend the roles of existing money services businesses and asset custodians.Comment: 24 pages, 7 figures, 2 table

The use of prepaid cards for banking the poor

Prepaid products can become an effective instrument for banking the poor, as they can be used for collecting microdeposits and so operate as a low-cost account. Prepaid platforms have characteristics that make them especially useful for developing low-cost microfinance business models. Indeed, customers using prepaid systems do not need bank accounts or debit or credit cards. Prepaid issuers do not need to develop or invest in new technologies, as this mechanism can be used on a range of platforms, including PCs, mobile phones, hand-held and set-top boxes. Furthermore, prepaid products are specially designed for offering services demanded by the poor, such as micropayments, microdeposits and even microcredits. Lastly, they allow users to monitor their cash flow by receiving statements (some providers offer this feature online, others provide physical statements) or accessing balances through PCs, mobile phones, hand-held and set-top boxes. Besides collecting microdeposits, prepaid products (or SVCs as they are called in the United States) offer other services that can be very valuable for serving the unbanked population. As explained in this paper, prepaid products generally lack the identification and credit requirements that effectively bar millions of individuals from opening traditional bank accounts, especially in the United States. Moreover, prepaid products can be purchased and reloaded at a growing number of locations other than bank branches, such as check cashers, convenience stores and other retailers. Prepaid instruments can also provide immediate availability of funds at a cost that, in some cases, is lower than other alternatives for unbanked consumers. Also, prepaid products are difficult to overdraw, thus reducing the likelihood of unexpected fees. Lastly, many prepaid issuers offer some sort of bill pay option, especially branded cards that enable signature-based transactions, and a significant number of them offer remittances.Prepaid card; microdeposits; mobile phone; store value card; e-money; banking the poor;