Key management is very important in the design for secure cryptosystem. Furthermore, data encryption and authentication require the ability to manage a large number of cryptographic keys. The purpose of this research was to investigate the techniques of key management for controlling the generation, distribution, operation, and updation of cryptographic keys. Of course, we deal with key management incorporating both conventional symmetric cryptosystem and public-key cryptosystem to provide communication and file security. Finally, we generalize the life cycle of key management.