We present a new and general method for optimizing homomorphic evaluation circuits. Although fully homomorphic encryption (FHE) holds the promise of enabling safe and secure third party computation, building FHE applications has been challenging due to their high computational costs. Domain-specific optimizations require a great deal of expertise on the underlying FHE schemes, and FHE compilers that aims to lower the hurdle, generate outcomes that are typically sub-optimal as they rely on manually-developed optimization rules. In this paper, based on the prior work of FHE compilers, we propose a method for automatically learning and using optimization rules for FHE circuits. Our method focuses on reducing the maximum multiplicative depth, the decisive performance bottleneck, of FHE circuits by combining program synthesis and term rewriting. It first uses program synthesis to learn equivalences of small circuits as rewrite rules from a set of training circuits. Then, we perform term rewriting on the input circuit to obtain a new circuit that has lower multiplicative depth. Our rewriting method maximally generalizes the learned rules based on the equational matching and its soundness and termination properties are formally proven. Experimental results show that our method generates circuits that can be homomorphically evaluated 1.18x – 3.71x faster (with the geometric mean of 2.05x) than the state-of-the-art method. Our method is also orthogonal to existing domain-specific optimizations.

Optimizing homomorphic evaluation circuits by program synthesis and term rewriting

Cloud computing is a promising computing model that enables convenient and on-demand network access to a shared pool of configurable computing resources. In cloud computing, data owners host their data on cloud servers and data consumers can access the data from cloud servers. This new paradigm of data storage service also introduces new security challenges, because data owners and data servers have different identities and different business interests. Therefore, an independent auditing service is required to make sure that the data is correctly hosted in the Cloud. However, the existing solutions are not specific to the multimedia data. Moreover copyright protection is not provided. In this paper, we define specially a provable data possession model for multimedia file, and present a framework based on digital watermarking for multimedia data storages audit service, in which we analyze the security features of audit service for multimedia data outsourcing and the corresponding properties of digital watermarking. Moreover as an example, we present a provable data possession scheme based on double function self-embedded digital watermark, which integrate image content audit service and copyright protection.

http://www.sersc.org/journals/IJMUE/vol9_no9_2014/24.pdf

Security Data Auditing based on Multifunction Digital Watermark for Multimedia File in Cloud Storage

It is our great pleasure to welcome you to the 2014 International Workshop on Security in Cloud Computing (SCC). Cloud computing has emerged as today's most exciting computing paradigm shift in information technology, since it promises numerous benefits, including lower costs, rapid scaling, easier maintenance, and ubiquitous availability. Meanwhile, cloud computing also raises many security and privacy challenges such as data protection, recovery, privacy, access control, trusted computing, as well as legal issues in areas such as regulatory compliance, auditing, and many others. This workshop aims to bring together the research efforts from both the academia and industry in all security aspects related to cloud computing.

This is the second year for our SCC workshop. We received 21 submissions from nine countries covering four continents, including Canada, China, Egypt, France, India, Oman, Sudan, Sweden, and United States. The submissions were reviewed by a technical program committee of 48 experts. The final program contains 9 papers, representing an acceptance rate of 43%.

Our program also features a keynote speech "On the Security of Cloud Data Storage and Sharing" by Dr. Jianying Zhou from Infocomm Security Department at Institute for Infocomm Research, Singapore.

Elaine Shi

Papers

Proceedings of the 2013 international workshop on Security in cloud computing