Corena and Ohtsuki apply three secure algorithms with additive homomorphism to the problem of securely storing financial information, such as customer receipts, on an untrusted cloud server. The three algorithms considered include a symmetric algorithm for efficient aggregation of information in sensor networks [1], Paillier’s public key additive homomorphic cryptosystem [2], and Shamir’s secret sharing scheme [3]. The authors implement all three algorithms as solutions to the given problem and compare their performance. To reduce server load when performing result aggregation, the authors also propose a simple fast aggregation algorithm that is based on dynamic programming.

The paper is well written and organized. It is structured as a survey paper and its main contribution lies in the application and practical comparison of the three existing algorithms. While the authors do not provide any substantially new algorithms, the application of existing algorithms to the problem of securing financial data in a cloud server will be of particular interest to practitioners in this field.