Encryption as a file security measure in large operating systems

A general review of the need for security, physical security measures, personnel practices, and administrative procedures was used to establish a foundation for the use of computer technology to supplement all other techniques. Hardware and software technologies were reviewed and several existing computer systems were briefly examined from a security standpoint. Historical developments leading up to the modern day interest in encryption were summarized. The DES was described and major criticisms of this algorithm enumerated, prior to examination of IBM's implementations and support of the algorithm in software and hardware.

The Programmed Cryptographic Facility, a software version of the DES, was found to have two major limitations: lack of accessibility to the high level language programmer and inability to achieve high speed. Previous software product developments have suggested that the first limitation may disappear in the future; the second can only be overcome by hardware.

The 3848 Cryptographic Unit is the primary hardware device which implements the DES and was also found to have two limitations. It is a channel-attached device, which increases the load on the input/output subsystem, and it can handle only four kilobytes of data at one time. Recommendations were made to incorporate the DES circuits into the input/output channel and also to provide a pair of encryption instructions for the central processing unit.

The increasing use of computers and data processing services in sensitive areas such as electronic funds transfer systems requires that some form of data encryption be included to assure adequate security. Developments in areas such as very large scale integration, data base management systems, international data flows, and language extensions are likely to provide capabilities to meet this requirement. Encryption is a powerful capability that must be included in security plans, and security must be a major concern in the design of any new system.