Paper 2018/114

Offline Assisted Group Key Exchange

Colin Boyd, Gareth T. Davies, Kristian Gjøsteen, and Yao Jiang

Abstract

We design a group key exchange protocol with forward secrecy where most of the participants remain offline until they wish to compute the key. This is well suited to a cloud storage environment where users are often offline, but have online access to the server which can assist in key exchange. We define and instantiate a new primitive, a blinded KEM, which we show can be used in a natural way as part of our generic protocol construction. Our new protocol has a security proof based on a well-known model for group key exchange. Our protocol is efficient, requiring Diffie-Hellman with a handful of standard public key operations per user in our concrete instantiation.

Note: Formatting changes and typo fixes.

Metadata
Available format(s)
PDF
Publication info
Published elsewhere. Minor revision. ISC 2018
Keywords
Authenticated Key ExchangeGroup Key ExchangeForward SecrecyCloud StorageBlinded Key Encapsulation
Contact author(s)
yao jiang @ ntnu no
History
2018-07-03: last of 3 revisions
2018-01-31: received
See all versions
Short URL
https://ia.cr/2018/114
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2018/114,
      author = {Colin Boyd and Gareth T.  Davies and Kristian Gjøsteen and Yao Jiang},
      title = {Offline Assisted Group Key Exchange},
      howpublished = {Cryptology ePrint Archive, Paper 2018/114},
      year = {2018},
      note = {\url{https://eprint.iacr.org/2018/114}},
      url = {https://eprint.iacr.org/2018/114}
}
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