A Fast Method for the Cryptanalysis of Substitution Ciphers

A Fast Method for the Cryptanalysis of Substitution Ciphers (1995)

by Thomas Jakobsen

Venue:	Cryptologia
Citations:	14 - 1 self

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Datum	Value	Source
TITLE	A Fast Method for the Cryptanalysis of Substitution Ciphers	user correction - Legacy Corrections
AUTHOR NAME	Thomas Jakobsen	SVM HeaderParse 0.1
AUTHOR AFFIL	y	SVM HeaderParse 0.2
ABSTRACT	It is possible to cryptanalyze simple substitution ciphers (both monoand polyalphabetic) by using a fast algorithm based on a process where an initial key guess is refined through a number of iterations. In each step the plaintext corresponding to the current key is evaluated and the result used as a measure of how close we are in having discovered the correct key. It turns out that only knowledge of the digram distribution of the ciphertext and the expected digram distribution of the plaintext is necessary to solve the cipher. The algorithm needs to compute the distribution matrix only once and subsequent plaintext evaluation is done by manipulating this matrix only, and not by decrypting the ciphertext and reparsing the resulting plaintext in every iteration. The paper explains the algorithm and it shows some of the results obtained with an implementation in Pascal. A generalized version of the algorithm can be used for attacking other simple ciphers as well. Keywords: Cryptanalysis,...	user correction - Legacy Corrections
YEAR	1995	INFERENCE
VENUE	Cryptologia	INFERENCE
VENUE TYPE	JOURNAL	INFERENCE
PAGES	265--274	INFERENCE
VOLUME	19	INFERENCE
TECH	Technical	INFERENCE
CITATIONS	7 found	ParsCit 1.0