Polyalphabetic Case: Probable Words

  • Friedrich L. Bauer


Pattern finding, using the positive coincidence of two text patterns, is necessarily restricted to monoalphabetic encryptions. But for a wide class of polyalphabetic encryptions, namely for those with fixpoint-free encryption steps, whose alphabets fulfill the condition “no letter may represent itself,” there is no coincidence between plaintext and cryptotext. This allows us to exclude certain positions of a probable word and thus establishes the remaining ones as possible positions. It is a probable word attack by exhausting positions. Exhaustion runs only over the length of the text and is feasible.


Rotor Position Probable Word Medium Rotor Boldface Type Encryption Step 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Friedrich L. Bauer
    • 1
  1. 1.Department of Computer ScienceMunich Institute of TechnologyMunichGermany

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