Title
Breaking substitution cyphers using stochastic automata
Abstract
Let Lambda be a finite plaintext alphabet and V be a cypher alphabet with the same cardinality as Lambda . In all one-to-one substitution cyphers, there exists the property that each element in V maps onto exactly one element in Lambda and vice versa. This mapping of V onto Lambda is represented by a function T*, which maps any v in V onto some lambda in Lambda (i.e., T*(v)= lambda ). The problem of learning the mapping of T* (or its inverse (T*)/sup -1/) by processing a sequence of cypher text is discussed. The fastest reported method to achieve this is a relaxation scheme that utilizes the statistical information contained in the unigrams and trigrams of the plaintext language. A new learning automaton solution to the problem called the cypher learning automaton (CLA) is given. The proposed scheme is fast, and the advantages of the scheme in terms of time and space requirements over the relaxation method have been listed. Simulation results comparing both cypher-breaking techniques are presented.
Year
DOI
Venue
1993
10.1109/34.192492
Pattern Analysis and Machine Intelligence, IEEE Transactions
Keywords
Field
DocType
cryptography,learning systems,relaxation theory,stochastic automata,automaton solution,cardinality,cypher alphabet,cypher learning automaton,finite plaintext alphabet,learning,relaxation scheme,statistical information,stochastic automata,substitution cyphers,trigrams,unigrams
Discrete mathematics,Inverse,Combinatorics,Learning automata,Binary lambda calculus,Automaton,Cardinality,Ciphertext,Plaintext,Mathematics,Lambda
Journal
Volume
Issue
ISSN
15
2
0162-8828
Citations 
PageRank 
References 
4
0.57
5
Authors
2
Name
Order
Citations
PageRank
B. John Oommen1759143.24
Zgierski, J.R.2162.01