A genetic algorithm is used to find the keys of Type II periodic polyalphabetic ciphers with mixed primary alphabets. Because of the difficulty of the ciphertext only cryptanalysis for Type II ciphers, a parallel, multi-phased search strategy is used, each phase of which recovers a bigger portion of the key.

R. A. Morelli, R.E.Walde, and W. Servos (2004). A study of heuristic search algorithms for breaking short cryptograms. International Journal of Artificial Intelligence Tools (IJAIT), 13(1), pp. 45-64.

In this study, we compare the use of genetic algorithms (GAs) and other forms of heuristic search in the cryptanalysis of short cryptograms. This paper expands on the work presented at FLAIRS-2003, which established the feasibility of a word-based genetic algorithm (GA) for analyzing short cryptograms. In this study the following search heuristics are compared both theoretically and experimentally: hill-climbing, simulated annealing, word-based and frequency-based genetic algorithms. Although the results reported apply to substitution ciphers in general, we focus in particular on short substitution cryptograms, such as the kind found in newspapers and puzzle books. Short cryptograms present a more challenging form of the problem. The word-based approach uses a relatively small dictionary of frequent words. The frequency-based approaches use frequency data for 2-, 3- and 4-letter sequences. The study shows that all of the optimization algorithms are successful at breaking short cryptograms, but perhaps more significantly, the most important factor in their success appears to be the choice of fitness measure employed.

R.A. Morelli and R.E. Walde (2003). A word-based genetic algorithm for cryptanalysis of short cryptograms. Proceedings of the 2003 Florida Artificial Intelligence Research Symposium (FLAIRS-2003). pp. 229-233.

This paper demonstrates the feasibility of a word-based genetic algorithm (GA) for solving short substitution cryptograms such as the kind found in newspapers and puzzle books. Although GA's based on analysis of letter, digram, or trigram frequencies have been used on substitution cryptograms, they are not able to solve short (10-30 word) cryptograms of the sort we address. By using a relatively small dictionary of frequent words to initialize a set of substitution keys, and by employing a word-based crossing mechanism, the GA achieves performance that is comparable to deterministic word-based algorithms.

R. A. Morelli, R. Walde, G. Marcuccio. (2001). A Java API for historical ciphers: An object oriented design project. Proceedings of the 2001 Symposium of the Special Interest Group on Computer Science Education (SIGCSE). pp. 307-311.

This paper describes a project suitable for a software engineering or object-oriented design course. The project consists of asking students to design an application programming interface (API) for a particular range of applications. An API-design project has several features not always found in application-design projects: It forces students to focus carefully on the distinction between the programming and the user interfaces; it provides a good justification for studying existing APIs as model code; it provides a natural way to divide tasks between different groups of designers/programmers; and, the final product can be used as the basis for programming projects in other courses. In this case the particular project we describe is the design of an API for implementing Historical Cipher algorithms.