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Lattice Codes for CRYSTALS-Kyber
  • Shuiyin Liu ,
  • Amin Sakzad
Shuiyin Liu
Holmes Institute

Corresponding Author:[email protected]

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Amin Sakzad
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This letter describes a lattice encoder for the NIST-recommended post-quantum encryption algorithm: Kyber. The key idea is to refine the analysis of Kyber decoding noise. We prove that Kyber decoding noise can be bounded by a sphere. This result shows the Kyber encoding problem is essentially a sphere packing in a hypercube. Lattice codes are then constructed to ensure denser packing and a lower decryption failure rate (DFR). Compared with the original Kyber encoder, the communication cost is reduced by up to 32.6%, the DFR is reduced by a factor of up to 2^{85}. The security arguments remain the same.