Ciphertext- and Polynomial-Level Optimization for Fully Homomorphic Encryption

• URL: http://arxiv.org/abs/2607.15750v2
• Date: Mon, 20 Jul 2026 09:40:26 GMT
• Title: Ciphertext- and Polynomial-Level Optimization for Fully Homomorphic Encryption
• Abstract summary: Fully homomorphic encryption (FHE) schemes such as RNS-CKKS enable privacy-preserving services through direct computation on data.<n>Recent FHE compilers optimize FHE programs at the ciphertext level, where each ciphertext operation comprises a sequence of operations.<n>This work presents Recifhe, a new multi-level compiler that supports both ciphertext-level and multi-level optimization.
• Score: 17.164955772341308
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Fully homomorphic encryption (FHE) schemes such as RNS-CKKS enable privacy-preserving services through direct computation on encrypted data. While recent FHE compilers optimize FHE programs, they operate at the coarse-grained ciphertext level, where each ciphertext operation comprises a sequence of polynomial operations. At this granularity, the compilers miss polynomial-level optimization opportunities across ciphertext operations. This work presents Recifhe, a new multi-level compiler that supports both ciphertext-level and polynomial-level optimization. At the ciphertext level, Recifhe transforms a non-FHE input program into an FHE program by inserting ciphertext management operations and applies global optimizations. At the polynomial level, Recifhe eliminates redundant polynomial computations across ciphertext operations. Recifhe achieves a 1.25x speedup over ciphertext-level-only optimization.

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