Robust Dictionary Attack of Short Simple Substitution Ciphers

Cryptologia, 2007

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Simple substitution ciphers are a class of puzzles often found in newspapers, in which each plaintext letter is mapped to a fixed ciphertext letter and spaces are preserved. In this paper, we describe a system for automatically solving them, even when the ciphertext is too short for statistical analysis, and when the puzzle contains non-dictionary words. Our approach is a based around a dictionary attack; we describe several important performance optimizations, as well as effective techniques for dealing with non-dictionary words. We present quantitative performance results for several variations of our approach as well as two other implementations.


    AUTHOR     = {Edwin Olson},
    TITLE      = {Robust Dictionary Attack of Short Simple Substitution Ciphers},
    JOURNAL    = {Cryptologia},
    MONTH      = {October},
    YEAR       = {2007},
    VOLUME     = {31},
    NUMBER     = {4},
    PAGES      = {332 - 342},