Protecting Big Data Privacy Using Randomized Tensor Network Decomposition and Dispersed Tensor Computation

Data privacy is an important issue for organizations and enterprises to securely outsource data storage, sharing, and computation on clouds / fogs. However, data encryption is complicated in terms of the key management and distribution; existing secure computation techniques are expensive in terms of computational / communication cost and therefore do not scale to big data computation. Tensor network decomposition and distributed tensor computation have been widely used in signal processing and machine learning for dimensionality reduction and large-scale optimization. However, the potential of distributed tensor networks for big data privacy preservation have not been considered before, this motivates the current study. Our primary intuition is that tensor network representations are mathematically non-unique, unlinkable, and uninterpretable; tensor network representations naturally support a range of multilinear operations for compressed and distributed / dispersed computation. Therefore, we propose randomized algorithms to decompose big data into randomized tensor network representations and analyze the privacy leakage for 1D to 3D data tensors. The randomness mainly comes from the complex structural information commonly found in big data; randomization is based on controlled perturbation applied to the tensor blocks prior to decomposition. The distributed tensor representations are dispersed on multiple clouds / fogs or servers / devices with metadata privacy, this provides both distributed trust and management to seamlessly secure big data storage, communication, sharing, and computation. Experiments show that the proposed randomization techniques are helpful for big data anonymization and efficient for big data storage and computation.

MPC-enabled Privacy-Preserving Neural Network Training against Malicious Attack

In the past decades, the application of secure multiparty computation (MPC) to machine learning, especially privacy-preserving neural network training, has attracted tremendous attention from both academia and industry. MPC enables several data owners to jointly train a neural network while preserving their data privacy. However, most previous works focus on semi-honest threat model which cannot withstand fraudulent messages sent by malicious participants. In this work, we propose a construction of efficient $n$-party protocols for secure neural network training that can secure the privacy of all honest participants even when a majority of the parties are malicious. Compared to the other designs that provides semi-honest security in a dishonest majority setting, our actively secured neural network training incurs affordable efficiency overheads. In addition, we propose a scheme to allow additive shares defined over an integer ring $\mathbb{Z}_N$ to be securely converted to additive shares over a finite field $\mathbb{Z}_Q$. This conversion scheme is essential in correctly converting shared Beaver triples in order to make the values generated in preprocessing phase to be usable in online phase, which may be of independent interest.