This is a study on a certain group theoretic property of the set of encryption functions of a block cipher. We have shown how to construct a subset which has this property in a given symmetric group by a computer algebra software GAP4.2 (Groups, Algorithms, and Programming, Version 4.2). These observations on group structures of block ciphers suggest us that we may be able to set a trapdoor based on meet-in-the-middle attack on block ciphers.
SAWADA Hideki. On a Certain Algebraic Property of Block Ciphers[J]. IEICE transactions on fundamentals of electronics, communications and computer sciences,2001-05-01,E84-A(5):1130-1134.