PrivCrowd: A Secure Blockchain-Based Crowdsourcing Framework with Fine-Grained Worker Selection

Algorithm 1

The smart contract: PostTask.

Input: This contract’s address ; requester’s public key ; requester’s certificate ; task identifier ; description of the task ; deadline of submission ; total reword ; reward per solution ; encrypted task’s data(metadata) ; signature of posting task .

1: for each and do

2: if

3:  goto final; Certificate invalid or requester unregister

4: end if

5: then

6:  goto final; Posting task's signature invalid

7: end if

8: if getBalance() then

9:  goto final; Deposit Insufficient

10: end if

11: while is not expired do

12:  broadcast(, , , , ) as a new task identified by ;

13:  transfer();

14: end while

15: end for

16: final;

17: return;