Paper 2016/1157

NewHope without reconciliation

Erdem Alkim, Léo Ducas, Thomas Pöppelmann, and Peter Schwabe


In this paper we introduce NewHope-Simple, a variant of the NewHope Ring-LWE-based key exchange that is using a straight-forward transformation from Ring-LWE encryption to a passively secure KEM (or key-exchange scheme). The main advantage of NewHopeLP-Simple over NewHope is simplicity. In particular, it avoids the error-reconciliation mechanism originally proposed by Ding. The explanation of his method, combined with other tricks, like unbiasing the key following Peikert's tweak and using the quantizer $D_4$ to extract one key bit from multiple coefficients, takes more than three pages in the NewHope-Simple paper. The price for that simplicity is small: one of the exchanged messages increases in size by $6.25\%$ from $2048$ bytes to $2176$ bytes. The security of NewHopeLP is the same as the security of NewHope; the performance is very similar.

Note: Added a discussion about concurrent related work by Jin and Zhao

Available format(s)
Public-key cryptography
Publication info
Preprint. MINOR revision.
Post-quantum key exchangeNewHopecode simplicity
Contact author(s)
newhope @ cryptojedi org
2017-11-09: revised
2016-12-21: received
See all versions
Short URL
Creative Commons Attribution


      author = {Erdem Alkim and Léo Ducas and Thomas Pöppelmann and Peter Schwabe},
      title = {NewHope without reconciliation},
      howpublished = {Cryptology ePrint Archive, Paper 2016/1157},
      year = {2016},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.