Credit Model Based On P2P Electronic Cash System Bitcoin

In recent years, with the fast development of Internet and distributed network technology, distributed applications(i.e. grid computing, cloud computing, Peer-to-peer system, etc.) become more and more popular not only in research field, but also industry and commercial field. The biggest characteristic of the distributed system is that it can coordinate and control distribution of different kinds of resources in the network because of its loose coupling structure.In order to accelerate the sharing of the resources, distributed system must adopt a metalism which can handle distribution of resources and inspire contribution. When the quantity of resouces is far less than the need, it is easy to select any of the mechanism. However, when the existing or new-coming resources are limited in the network, we must be more cautious to adopt a more efficient distribution mechalism.When we look back to the human economic society development, we will find it is a natural transformation from barter interchange to currency. Currency can be used to make transactions, evaluate price, save value and pay the deal. Human society just like a real P2P distributed system. In real society, people use currency to change commodities with different value and they don't need to take trouble to decide the value of the good to exchange because currency can take the responsibility to evaluate the price. And the best thing of using currency is that one can get other things of same value in the future when he needs something with the money he gets today, this is how money works as a method of value storation. Bitcoin is a kind of pure P2P digital cash which can meet the need of decentralization, and the total amount of the currency can be evaluated, thus it will limit the probability of inflation. By using digital cash in P2P network, nodes can have reasonable evaluation about the resources and can exchange resources conveniently. Meanwhile, in order to get more money, nodes must contribute some amount of resources or services. All the transactions are modulated by the market, the system let the market to decide the distribution and transactions of the resources. We'd like to take this as the entry point and have a study on the theory of Bitcoin system. We also analyse the problem and challenage Bitcoin face as a pure distributed digital currency.In order to solve three problems in Bitcoin system, which in sequence are small amount payment, anonymity and double-spending. We would like to introduce credit into the Bitcoin system so that nodes can build their reputation and thus help optimize the whole economic environment. We propose a protocol, which let nodes, which we call them banks, have large amount of money provide credit amount to appliers and thus help them with turnover of capital and small transactions. Nodes can borrow the trust of these reliable banks to shorten the time a seller required to wait to make sure he does get the money. Another function of trust is to build the trust evaluation for those active nodes. In order to protect their trust level, nodes must be more careful to avoid the"wrong action". The protocol we propose include the application flow, payment flow and return flow, and we analyse the security of introducing the trust.