A Collusion-Resistant and Privacy-Preserving Data Aggregation Protocol in Crowdsensing System

Algorithm 2

Verify&Dec.

Input:

For each user , input his/her pseudo ID , public signing key and uploaded data and .

The time period and the aggregator’s decryption keys are requested.

The symbol and have the same meaning in Algorithm .

Output:

The aggregator outputs all the users’ original data as follows:

begin

 () Aggregate all the signatures and verify them:

 () If the equation in Step () does not hold, the algorithm outputs −1, otherwise continue to compute:

 () The aggregator calculates the final result as:

 () Output .

end