Graph Chaining

One way of doing alphabet chaining is to build up a directed graph where the nodes are the ciphertext symbols. The edges are colored, with a different color for each pair of isomorphs in a set. The edges are added for each substitution (e.g. symbol X -> symbol Y) between that pair of isomorphs, so the ciphertext symbols in the same relative position within the isomorph. For Group Autokey (GAK) ciphers, this is equivalent to building a subgraph of the Schreier Coset Graph.