Paper 2023/823

Lattice-based Authenticated Key Exchange with Tight Security

Jiaxin Pan, Norwegian University of Science and Technology
Benedikt Wagner, CISPA Helmholtz Center for Information Security, Saarland University
Runzhi Zeng, Norwegian University of Science and Technology

We construct the first tightly secure authenticated key exchange (AKE) protocol from lattices. Known tight constructions are all based on Diffie-Hellman-like assumptions. Thus, our protocol is the first construction with tight security from a post-quantum assumption. Our AKE protocol is constructed tightly from a new security notion for key encapsulation mechanisms (KEMs), called one-way security against checkable chosen-ciphertext attacks (OW- ChCCA). We show how an OW-ChCCA secure KEM can be tightly constructed based on the Learning With Errors assumption, leading to the desired AKE protocol. To show the usefulness of OW-ChCCA security beyond AKE, we use it to construct the first tightly bilateral selective-opening (BiSO) secure PKE. BiSO security is a stronger selective-opening notion proposed by Lai et al. (ASIACRYPT 2021).

Note: Minor Editorial Changes

Available format(s)
Public-key cryptography
Publication info
A minor revision of an IACR publication in CRYPTO 2023
Authenticated Key ExchangeLatticesTight SecuritySelective-Opening SecurityRandom Oracle
Contact author(s)
jiaxin pan @ ntnu no
benedikt wagner @ cispa de
runzhi zeng @ ntnu no
2023-06-07: last of 2 revisions
2023-06-02: received
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      author = {Jiaxin Pan and Benedikt Wagner and Runzhi Zeng},
      title = {Lattice-based Authenticated Key Exchange with Tight Security},
      howpublished = {Cryptology ePrint Archive, Paper 2023/823},
      year = {2023},
      note = {\url{}},
      url = {}
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