Computer security and encryption is the effort to create a secure computing platform. So that the users or program can only perform actions that have been allowed. This involves specifying and implementing a security policy. System is secured if its resources are used and accessed as intended under all circumstances. Protection is the internal problem. Security must consider both the computer system and the environment with in which the system is used. The data stored in the computer system must be protected from unauthorized access malicious destruction or alteration and accidental introduction of inconsistency. The various authorization provisions in a computer system may not confer sufficient protection for a highly sensitive data. In such cases, data may be encrypted to be read unless the leader knows how to decipher the encrypted data.