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DPHE: Protecting Server Privacy in CKKS-based Protocols
TL;DR: We investigate methods for protecting server privacy in CKKS-based protocols. Unlike exact homomorphic encryption schemes, formally defining security notions for the server is challenging in CKKS-based protocols due to the approximate nature of CKKS. We address this by introducing a new security notion called Differentially Private Homomorphic Encryption, which is motivated by differential privacy. Based on this notion, we construct a general compiler that transforms CKKS-based protocols into DPHE protocols. We also present the first zero-knowledge argument of knowledge for CKKS ciphertexts to protect server privacy against malicious clients.
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Homomorphic Encryption for Data Science
TL;DR: We introduce a new high-precision CKKS bootstrapping method. It leverages a novel Integer Cleaning strategy inspired by the Discrete CKKS technique and is implemented using the Grafting technique. We highlight its main building blocks and discuss its efficiency.
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A Novel Asymmetric BSGS Polynomial Evaluation Algorithm under Homomorphic Encryption
TL;DR: We introduce a new polynomial evaluation algorithm under homomorphic encryption, namely the Asymmetric BSGS Algorithm. It is a generalization and specialization of the original Baby-Step Giant-Step algorithm in the leveled FHE computation model. Leveraging the observation that there is a difference in multiplicative depth between the baby-step set and the giant-step set, this algorithm significantly reduces the number of modulus and key switches required for dense polynomial evaluation from $$O(\sqrt{d})$$ to $$O(d^{1/t})$$, by adjusting the set decomposition method and relaxing the control of noise growth and ciphertext size in some calculations. Here, $$d$$ is the polynomial degree and $$t$$ is a small constant which, according to our experiments, is recommended to be chosen as $$4$$.
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Convergent Evolution: Why Secure Homomorphic Encryption Will Resemble High-Performance GPU Computing
TL;DR: Fully Homomorphic Encryption (FHE) programming hits a fundamental Turing Barrier where secure computation forbids the dynamic branching that makes conventional software work, forcing it into a parallel-first paradigm surprisingly similar to the high-performance GPU model. This means the future of FHE isn't a magic compiler, but a hybrid architecture where a trusted client orchestrates complex logic, while an untrusted server executes simple, branchless secure kernels on encrypted data across a well-defined offloading boundary. Ultimately, developers must stop trying to translate old optimization habits and start redefining problems from the ground up, because in the world of FHE, performance isn't about pruning—it's about parallelism.
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Leveraging Discrete CKKS to Bootstrap in High Precision
TL;DR: We introduce a new high-precision CKKS bootstrapping method. It leverages a novel Integer Cleaning strategy inspired by the Discrete CKKS technique and is implemented using the Grafting technique. We highlight its main building blocks and discuss its efficiency.