Paper 2017/589

An Attempt to Cryptanalyze A Partially Known Cipher Algorithm

Juay Guan Hee


This paper presents an empirical crypt-analytical method to analyse a partially known cipher algorithm. During cipher evaluation, it is always a challenge to make any decision on the strength of a partially known cipher algorithm, and if the algorithm is suitable for deployment. The core concept will be presented first, followed by an example to illustrate the idea. The idea is to focus on one input bit at a time using a known keystream attack, assuming this bit is independent from the rest. By computing the statistics of related keystream bits and using the correlation method, one can derive this input bit with certain confidence.

Note: Please note that this is NOT a randomness test. This is a proven concept tested using simulation, as well as using double blind method. With this method, one can analyze a particular type of cipher with the linear complexity instead of exponential complexity.

Available format(s)
Secret-key cryptography
Publication info
Preprint. MINOR revision.
Linear Feedback Shift RegisterCorrelation CoefficientStream Cipher.
Contact author(s)
hjuaygua @ gmail com
2017-06-20: received
Short URL
Creative Commons Attribution


      author = {Juay Guan Hee},
      title = {An Attempt to Cryptanalyze A Partially Known Cipher Algorithm},
      howpublished = {Cryptology ePrint Archive, Paper 2017/589},
      year = {2017},
      note = {\url{}},
      url = {}
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