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

Algorithm 2

The smart contract: CollectSol.

Input: This contract’s address ; worker’s public key ; workers’s certificate ; workers’s deposit ; task identifier ; solution evaluation function ; deadline of submission ; total reword ; reward per solution .

1: while (getBalance() ) and is not expired do

2: Upon receiving a signed submission from , parses the submission as ();

3: ifthen

4:  continue; Certificate invalid or worker unregister

5: end if

6: ifthen

7:  continue; Submission's signature invalid

8: end if

9: if is not sufficient then

10:  continue; Worker's deposit is not sufficient

11: end if

12: if SNARK.Verifythen

13:  Send to the request ; Forward the solution to the requester

14:  transfer(); Pay the reward and refund the deposit

15:  UpdateProf();Invoke the smart contract UpdateProf

16: end if

17: end while

18: if getBalance() then Refund residue money to the request

19: transfer(

20: );

21: end if

22: return;