As cloud computing gains traction, data owners are outsourcing their data to cloud service providers (CSPs) for Database Service (DBaaS), bringing in a deviation of data ownership and usage, and intensifying privacy concerns, especially with potential breaches by hackers or CSP insiders. To address that, encrypted database services propose encrypting every tuple and query statement before submitting to the CSP, ensuring data confidentiality when the CSP is honest-but-curious, or even compromised. Existing solutions either employ property preserving cryptography schemes, which can perform certain operations over ciphertext without decrypting the data over the CSP, or utilize trusted execution environment (TEE) to safeguard data and computations from the CSP. Based on these efforts, we introduce Enc2DB, a novel secure database system, following a hybrid strategy on PostgreSQL and openGauss. We present a micro-benchmarking test and self-adaptive mode switch strategy that can dynamically choose the best execution path (cryptography or TEE) to answer a given query. Besides, we also design and implement a ciphertext index compatible with native cost model and query optimizers to accelerate query processing. Empirical study over TPC-C test justifies that Enc2DB outperforms pure TEE and cryptography solutions, and our ciphertext index implementation also outperforms the state-of-the-art cryptographic-based system.

翻译：随着云计算的普及，数据所有者将其数据外包给云服务提供商（CSP）以获取数据库服务（DBaaS），这导致了数据所有权与使用权的分离，并加剧了隐私问题，特别是当面临黑客或CSP内部人员潜在的入侵时。为此，加密数据库服务提出在将数据提交至CSP前对每个元组和查询语句进行加密，以确保在CSP保持诚实但好奇甚至被攻陷情况下数据的机密性。现有解决方案要么采用属性保持加密方案（可在不解密数据的情况下对CSP上的密文执行特定操作），要么利用可信执行环境（TEE）保护数据及计算免受CSP干扰。基于这些工作，我们提出了Enc2DB——一种采用混合策略的新型安全数据库系统（基于PostgreSQL和openGauss）。我们设计了一种微基准测试与自适应模式切换策略，能够动态选择最佳执行路径（加密或TEE）来响应给定查询。此外，我们还设计并实现了与原生成本模型及查询优化器兼容的密文索引，以加速查询处理。在TPC-C测试集上的实验表明，Enc2DB的性能优于纯TEE和纯加密方案，且我们的密文索引实现也优于当前最先进的基于密码学的系统。