Paper 2006/264

A Simple and Unified Method of Proving Unpredictability

Mridul Nandi


Recently Bernstein has provided a simpler proof of unpredictability of CBC construction which is giving insight of the construction. Unpredictability of any function intuitively means that the function behaves very closely to a uniform random function. In this paper we make a unifying and simple approach to prove unpredictability of many existing constructions. We first revisit Bernstein's proof. Using this idea we can show a simpler proof of unpredictability of a class of DAG based construction, XCBC, TMAC, OMAC and PMAC. We also provide a simpler proof for stronger bound of CBC and a simpler proof of security of on-line Hash-CBC. We note that there is a flaw in the original security proof of Hash-CBC. This paper will help to understand security analysis of unpredictability of many constructions in a simpler way.

Available format(s)
Publication info
Published elsewhere. Unknown where it was published
Contact author(s)
mridul nandi @ gmail com
2006-08-08: received
Short URL
Creative Commons Attribution


      author = {Mridul Nandi},
      title = {A Simple and Unified Method of Proving Unpredictability},
      howpublished = {Cryptology ePrint Archive, Paper 2006/264},
      year = {2006},
      note = {\url{}},
      url = {}
Note: In order to protect the privacy of readers, does not use cookies or embedded third party content.