Paper 2015/1220

Two-Round Man-in-the-Middle Security from LPN

David Cash, Eike Kiltz, and Stefano Tessaro


Secret-key authentication protocols have recently received a considerable amount of attention, and a long line of research has been devoted to devising efficient protocols with security based on the hardness of the learning-parity with noise (LPN) problem, with the goal of achieving low communication and round complexities, as well as highest possible security guarantees. In this paper, we construct 2-round authentication protocols that are secure against sequential man-in-the-middle (MIM) attacks with tight reductions to LPN, Field-LPN, or other problems. The best prior protocols had either loose reductions and required 3 rounds (Lyubashevsky and Masny, CRYPTO'13) or had a much larger key (Kiltz et al., EUROCRYPT'11 and Dodis et al., EUROCRYPT'12). Our constructions follow from a new generic deterministic and round-preserving transformation enhancing actively-secure protocols of a special form to be sequentially MIM-secure while only adding a limited amount of key material and computation.

Available format(s)
Secret-key cryptography
Publication info
Published by the IACR in TCC 2016
Secret-key authenticationMan-in-the-Middle securityLPNField LPN.
Contact author(s)
tessaro @ cs ucsb edu
2015-12-23: received
Short URL
Creative Commons Attribution


      author = {David Cash and Eike Kiltz and Stefano Tessaro},
      title = {Two-Round Man-in-the-Middle Security from LPN},
      howpublished = {Cryptology ePrint Archive, Paper 2015/1220},
      year = {2015},
      note = {\url{}},
      url = {}
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