Algorithm 2. PDAAS_CellHeader_Aggregate.

Input:

Perturbed data items di, i∈{1,2,…Nj}

Output:

An intermediate aggregation result

Method:

1. Dj = 0;

2. Sj = Ø;

3. For each di do

3. $e{k}_i^j=Hash(f_{MCKj}(S_i)||n_j^{\mathit{\text{current}}})$ ;

3.2 Dj = Dj + di − $e{k}_i^j$;

3.3 Sj =Sj ∪ {si};

4. Sends <Sj, Dj> to the sink.