Efficient confidentiality-preserving data analytics over symmetrically encrypted datasets

Abstract

In the past decade, cloud computing has emerged as an economical and practical alternative to in-house datacenters. But due to security concerns, many enterprises are still averse to adopting third party clouds. To mitigate these concerns, several authors have proposed to use partially homomorphic encryption (PHE) to achieve practical levels of confidentiality while enabling computations in the cloud. However, these approaches are either not performant or not versatile enough. We present two novel PHE schemes, an additive and a multiplicative homomorphic encryption scheme, which, unlike previous schemes, are symmetric. We prove the security of our schemes and show they are more efficient than state-of-the-art asymmetric PHE schemes, without compromising the expressiveness of homomorphic operations they support. The main intuition behind our schemes is to trade strict ciphertext compactness for good "relative" compactness in practice, while in turn reaping improved performance. We build a prototype system called Symmetria that uses our proposed schemes and demonstrate its performance improvements over previous work. Symmetria achieves up to 7× average speedups on standard benchmarks compared to asymmetric PHE-based systems.

Rache: Radix-additive caching for homomorphic encryption

“…An HE scheme that supports multiplication is said to be multiplicative. Symmetria [19] is also multiplicative using a distinct scheme than the one for addition. Other well-known multiplicative HE schemes include RSA [18] and ElGamal [6].…”

“…An HE scheme that supports both addition and multiplication is called a fully HE scheme. This requirement should not be confused with specific addition and multiplication parameters, such as Symmetria [19] and NTRU [9]. That is, the addition and multiplication must be supported homomorphically under exactly the same scheme ℎ𝑒 (•):…”

“…An HE scheme that supports addition is said to be additive. Popular additive HE schemes include Symmetria [19] and Paillier [17]. The former is applied to symmetric encryption, meaning that a single secret key is used to both encrypt and decrypt the messages.…”

“…Although many HE schemes support only primitive arithmetic operations such as addition and multiplication, it turns out that many commonly-used operations can be implemented using addition and/or multiplication [7]. The first type of HE schemes, e.g., Symmetria [19], are implemented as a symmetric operation for the scenarios where a secret key can be securely shared among parties, which is not always possible in cloud computing. The second type of HE schemes, e.g., Paillier [17], are implemented as an asymmetric operation that overcomes the limitation of a symmetric one, and yet introduces significant performance overhead, making it impractical to encode a large volume of sensitive data.…”

INCHE: High-Performance Encoding for Relational Databases through Incrementally Homomorphic Encryption

“…However, in the context of DaaS, the user usually serves as both the sender and the receiver and there is no need to distribute the key. To this end, symmetric (partially) homomorphic encryption (SHE), was proposed [26,29]. This paper is along this line of research.…”