## Cryptology ePrint Archive: Report 2020/056

AKCN-E8: Compact and Flexible KEM from Ideal Lattice

Zhengzhong JIn and Yunlei Zhao

Abstract: A remarkable breakthrough in mathematics in recent years is the proof of the long-standing conjecture: sphere packing (i.e., packing unit balls) in the $E_8$ lattice is optimal in the sense of the best density \cite{V17} for sphere packing in $\mathbb{R}^8$. In this work, based on the $E_8$ lattice code, we design a mechanism for asymmetric key consensus from noise (AKCN), referred to as AKCN-E8, for error correction and key consensus. As a direct application of the AKCN-E8 code, we present highly practical key encapsulation mechanism (KEM) from the ideal lattice based on the ring learning with errors (RLWE) problem. Compared to the RLWE-based NewHope-KEM \cite{newhope-NIST}, which is a variant of NewHope-Usenix \cite{newhope15} and is now a promising candidate in the second round of NIST post-quantum cryptography (PQC) standardization competition, our AKCN-E8-KEM has the following advantages:

* The size of shared-key is doubled..

* More compact ciphertexts, at the same or even higher security level.

* More flexible parameter selection for tradeoffs among security, ciphertext size and error probability.

Category / Keywords: cryptographic protocols / post-quantum cryptography, lattice, KEM

Date: received 17 Jan 2020, last revised 22 Jan 2020

Contact author: ylzhao at fudan edu cn

Available format(s): PDF | BibTeX Citation

Short URL: ia.cr/2020/056

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