Brands E-cash Programs, Research And Improvement

Internet-based electronic commerce is globally flourishing and rapidly spreading all over the world, which becomes a key driver of economic growth. While electronic payment is the core of e-commerce activities, the most critical link. It is an important step to achieve the purpose of parties to the transaction and the basis of the conditions to proceed. Electronic cash is one of e-payment forms that have good qualities and functions, which can be used to pay both large and small payment, and which have many advantages, such as the concealment to protect the user's paying activities, avoiding overdraft and refusal paying. Therefore, e-cash becomes the key of the development of e-commerce. And it causes widespread concern and research.One of the key requirements of e-commerce activities on Internet is to have a safe and efficient electronic cash system, while the security and reliability of e-cash are mainly relying on cryptographic techniques. The first e-cash scheme was proposed in 1982. From then on, e-cash schemes have been widely studied. This paper takes a summary of e-cash and its some existing schemes. We also analyze the characters and efficiency of some representational schemes and present its development course.Brands proposed e-cash scheme is regarded as the most effective completely anonymous off-line ones till now, which is detailedly described and analyzed in this paper. The main contribution of this paper is to use a new method to improve the Brands scheme, and propose an e-cash scheme with various denominations which overcome the drawback that one denomination is corresponding to a pair of keys the bank holds. The improved scheme is more effective and safe than the original Brands one. In the improved scheme, the bank needs to choose only one private key if it must issue different denominations, which improves the security of the system. And we give simple proof that the improved scheme has the same security as the Brands proposed. For the popular"multiple banks"e-cash system, the paper utilizes bilinear pairings to deal with the application of Identity-based blind signature to the e-cash system and proposes an ID-based"multiple banks"e-cash system, which has strong security and high efficiency. Another contribution of this paper is to propose the concept of a relatively perfect"multiple banks"e-cash system which is concerned about the popular one. In the paper, we think and try to utilize the group-blind signature scheme to achieve this system.