Abstract
Homomorphic encryption allows computation on encrypted data at the cost of a significant loss in efficiency. In this paper we propose a powerful integer encoding for homomorphic encryption. The proposed encoding offers more efficient and convenient homomorphic computations on integers compared to previously used methods. This is possible by making the message space of the encryption scheme isomorphic to an integer quotient ring. The encoding can be used across various lattice-based homomorphic encryption schemes such as NTRU and various ring-LWE based schemes. We analyse the efficiency of our proposed encoding, which shows a significant gain compared to a naive integer encoding for a ring-LWE based scheme.
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Notes
- 1.
We use the notation \([a_{i,j}]\) to represent a matrix of input values.
- 2.
We set \(p'=3\) for \(p=x-2\) because for \(a\in R\) it holds that \(\left\| [(x-2)*a]_R\right\| _\infty \le 3\cdot \left\| a\right\| _\infty \).
- 3.
Benchmarks were written in C++ using NTL, a library for doing number theory, and run on a machine with an Intel Core i5-2557M CPU and 4GB of RAM.
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Geihs, M., Cabarcas, D. (2015). Efficient Integer Encoding for Homomorphic Encryption via Ring Isomorphisms. In: Aranha, D., Menezes, A. (eds) Progress in Cryptology - LATINCRYPT 2014. LATINCRYPT 2014. Lecture Notes in Computer Science(), vol 8895. Springer, Cham. https://doi.org/10.1007/978-3-319-16295-9_3
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DOI: https://doi.org/10.1007/978-3-319-16295-9_3
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