Encrypted deduplication is attractive for outsourced storage as it provides both data confidentiality and storage savings. Conventional encrypted deduplication schemes protect data confidentiality based on expensive cryptographic primitives, leading to performance degradation. Recently, several SGX-based schemes have been proposed to accelerate encrypted deduplication. However, these schemes have limitations in both security and performance aspects. This paper presents a SGX-based basic scheme to address these limitations, which first performs proof of ownership (PoW), followed by key generation and data encryption, realizing a new paradigm known as PoW-before-encryption (PbE) to solve the security issue in existing schemes. Additionally, the basic scheme implements deduplication-before-encryption (DbE) to reduce redundant computations, thus improving performance. Despite these improvements, the duplicate detection and key generation in the basic scheme still involve redundant computations. Consequently, we propose an epoch-based enhanced scheme that utilizes data locality and computation deduplication, which caches fresh computations in an epoch and reuses them to enhance performance. We provide a security analysis and evaluate the performance of our schemes using both synthetic and real-world workloads. The results demonstrate that our schemes offer stronger security guarantees while outperforming state-of-the-art schemes in terms of performance.

Popularity-based secure deduplication scheme classifies data based on their number of owners and provides different levels of security for a trade-off between privacy preservation and storage savings. Most existing schemes rely on a trusted third party to record data popularity using deterministic tags, which is impractical in reality. Recently, Ha et al. propose a scheme that uses random tags to record popularity without the need for a trusted third party. However, their scheme is vulnerable to a malicious cloud launching smuggle attacks (SAs) and popularity-faking attacks (PFAs), which poses security vulnerabilities. In this paper, we propose a privacy-preserving popularity-based deduplication scheme. For one thing, we use unforgeable random tags to record data popularity, which defends against SAs. For another thing, we design a verifiable interactive popularity detection scheme to assure the correctness of popularity detection and resist PFAs. Security analysis and evaluation results show that our proposed scheme provides stronger security guarantees with limited overhead compared with existing schemes.