Cryptography and encryption have been used for secure communication for thousands of years. Cryptography is about communication in the presence of an adversary. To carry sensitive information, such as military or financial data, a system must be able to secure privacy. Satellite and other wireless media can not be protected from the unauthorized access a more practical way to protect information is to alter it so that only an authorized receiver can understand it. This method is used today is cryptography. Oddly enough, cryptography is the art of secret writing. More generally, people think of cryptography as the art of mangling information into apparent unintelligibility in a manner allowing a secret method of unmangling. A more practical way to protect information is to alter it so that only an authorized receiver can understand it. This method used today is called the cryptography.