A switching closure test to analyze cryptosystems

The closure test MCT (meet-in-the-middle closure test) was introduced to analyze the algebraic properties of cryptosystems [KaRiSh]. Since MCT needs a large amount of memory, it is hard to implement with an ordinary meet-in-the-middle method. As a feasible version of MCT, this paper presents a switching closure test SCT which based on a new memoryless meet-in-the-middle method. To achieve the memoryless method, appropriate techniques, such as expansion of cycling detection methods for one function into a method for two functions and an efficient intersection search method that uses only a small amount of memory, are used in an extremely effective manner.