Data encryption (cryptography) is utilized in a variety of environments and applications. The exact utilization of encryption and the implementation of the DES will be based on many factors exacting to the computer system and its
related components. In common, cryptography is used to look after data while it is being communicated between two points or while it is stored in a medium vulnerable to physical theft. Communication security provides protection to data by encrypting it at the transmitting point and decrypting it at the in receipt of point. File security provides security to data by encrypting it when it is recorded on a storage medium and decrypting it when it is read back from the storage medium. In the first case, the key must be obtainable at the receiver and transmitter at the same time during communication. In the second case, the key must be accessible and maintained for the period of the storage duration. FIPS 171 provides accepted methods for organization the keys used by the algorithm particular in this standard.