Network security and cryptography is a concept to protect network and data transmission over wireless network. Network security typically relies on layers of protection and consist of multiple components including networking monitoring and security software in addition to hardware and applications. Keywords:- Fuzzy logic, Cryptography, Network security Introduction:- Cryptography in computer network security is the process of protecting sensitive information from unauthorized access when it is at rest or in transit by rendering it. Cryptosystem is the application of number theory. The hard problem in number theory uses to develop cryptosystem. Basically cryptosystem is the system for providing the security to the information. Modern world is the world of information. Some of the information requires the security such as; banking transactions, government security information, medicine information, military information, police information, economic information, password, debit card, credit card etc. This information is very important for the individual thus its security is also very important relatively. We focused on the cryptosystem based on fuzzy set. The properties of the fuzzy set are reviewed and its application presented as a cryptosystem. this system is claimed under the security, efficiency and smart to use. This gives smart decision also.