Cryptography is a method of protecting information and communications through the use of codes so that only those for whom the information is intended can read and process it. Modern cryptography uses sophisticated mathematical equations (algorithms) and secret keys to encrypt and decrypt data. Today, cryptography is used to provide secrecy and integrity to our data, and both authentication and anonymity to our communications. In this paper we have to encrypt and decrypt secret data using discrete Sumudu transformation and congruence modulo operator relation.