This paper examines the possibilities of applying Catalan numbers in cryptography. It also offers the application of appropriate combinatorial problems (Ballot Problem, Stack permutations and Balanced Parentheses) in encryption and decryption of iles and plaintext. The paper analyzes the properties of Catalan numbers and their relation to these combined problems. Applied copyright method is related to the decomposition of Catalan numbers in the process of ef icient keys generating. Java software solution which enables key generating with the properties of the Catalan numbers is presented at the end of the paper. Java application allows encryption and decryption of plaintext based on the generated key and combinatorial problems.

This paper analyzes the properties of Catalan numbers and their relation to the Lattice Path combinatorial problem in cryptography. Specifically, analyzes the application of the appropriate combinatorial problem based on Catalan-key in encryption and decryption of files and plaintext. Accordingly, we use Catalan numbers for generating keys and within the experimental part we have applied the NIST (National Institute of Standards and Technology) statistical battery of tests for assessing the quality of generated keys was applied. A total of 12 quality assurance tests for Catalan-key were applied. A Java application is presented which allows the encryption and decryption of plaintext based on the generated Catalan-key and combinatorial problem of movement in integer network orLattice Path. Experimental study yields the comparison of results in text encryption speed for combinatorial encryption methods (such as: Ballot Problem, Stack permutations and Balanced Parentheses) in comparison with Lattice Path method (in Java programming language).