A Bitcoin-Based Incentive Mechanism for Distributed P2P Applications
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but it does not know the route to the receiver. The sender should give rewards to the intermediate nodes who help transmit the message. Cooperative nodes can be divided into two types: negative cooperative nodes who help transmit the data but the receiver fails to receive the data, and positive cooperative nodes who help transmit the data and the receiver does successfully receive the data. In our consideration, the sender only pays back the positive cooperative nodes. In our model, the sender employs the Bitcoin system to pay back the positive cooperative nodes. The workflow of the payment consists of three steps. In the first step, the sender publicizes a transmission task and makes a certain deposit that is used to pay back the positive cooperative nodes. In the second step, the sender transmits data to the receiver by opportunistic connections. In the last step, the positive cooperative nodes get their payments. Suppose that a sender A sends a message m to a receiver E, and B, C, D are the positive cooperative nodes who help A transmit the data to E. The workflow of the payment is elaborated as follows. (1) Publishing a Transmission Task: A announces a task A → E : m and generates two random numbers R1 and R2 that should be kept secret. Then A makes a deposit to commit that it will give the rewards to the positive cooperative nodes if the message is successfully delivered; otherwise A would get the deposit back. The transcript of the transaction [1,3] is shown in Fig. 1. Deposit A (in : T A )
in - script : Sig SK A ( Deposit A ) Sender
Task : A m E h1 , h2
out - script pt: H ( R2 ) h2 (A i j E) E PK i ( h1 ) E PK A ( E PK i ( R1 )) E PK i ( E PK E ( ACK E )) E PK E ( E PK i ( ACK E ))
value : x coins time - lock : t
Fig. 1. A publishes a task and makes a deposit.
Fig. 2. A transmits the data to E.
(2) Data Transmission: The process of the data transmission from A to E is illustrated in Fig. 2. A first sends the message m||EP KE (R2 )||σ||SigSKA (R1 ) to