Paper 2018/1221

Using the Cloud to Determine Key Strengths -- Triennial Update

M. Delcourt, T. Kleinjung, A. K. Lenstra, S. Nath, D. Page, and N. Smart


We develop a new methodology to assess cryptographic key strength using cloud computing, by calculating the true economic cost of (symmetric- or private-) key retrieval for the most common cryptographic primitives. Although the present paper gives the current year (2018), 2015, 2012 and 2011 costs, more importantly it provides the tools and infrastructure to derive new data points at any time in the future, while allowing for improvements such as of new algorithmic approaches. Over time the resulting data points will provide valuable insight in the selection of cryptographic key sizes. For instance, we observe that the past clear cost-advantage of total cost of ownership compared to cloud-computing seems to be evaporating.

Available format(s)
Publication info
Preprint. MAJOR revision.
key lengthscloud computing
Contact author(s)
akl @ epfl ch
2019-01-11: revised
2018-12-30: received
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Creative Commons Attribution


      author = {M.  Delcourt and T.  Kleinjung and A. K.  Lenstra and S.  Nath and D.  Page and N.  Smart},
      title = {Using the Cloud to Determine Key Strengths -- Triennial Update},
      howpublished = {Cryptology ePrint Archive, Paper 2018/1221},
      year = {2018},
      note = {\url{}},
      url = {}
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