Introduction.- Homomorphic Public Key Encryption Techniques.- Privacy-Preserving Multidimensional Data Aggregation.- Privacy-Preserving Subset Data Aggregation.- Privacy-Preserving Multifunctional Data Aggregation.- Privacy-Preserving Data Aggregation with Fault Tolerance.- Differentially Private Data Aggregation with Fault Tolerance.- Privacy-Preserving Data Aggregation with Data Integrity and Fault Tolerance.