NCJ Number
79425
Date Published
1977
Length
38 pages
Annotation
This manual describes the history and benefits of cryptography as a data security technique and then details the implementation of cryptographic security measures in computerized information systems.
Abstract
An introduction reviews basic data security measures, including access control, journalizing and auditing, and concealment of information. The consequences of loss of data security are discussed, as are the burdens that new laws regarding privacy place on institutions that maintain files on individuals. Examples illustrate cryptography's effectiveness in protecting data that passes outside a controlled or protected environment, such as electronic funds transfers or wiretaps. The manual identifies factors that should be considered when appraising the economic effects of a data loss versus the costs of installing extra security measures. Following a brief history of cryptography from the ancient Egyptians to modern automatic devices, the basic transformation process which scrambles and modifies the input data according to a built-in algorithm is described. The manual emphasizes that the computer lends itself to cryptography because of the logical nature of the algorithm, producing inexpensive and effective data protection. A discussion of the general implementation considerations focuses on key selection and key management, since a common key-controlled algorithm of known strength is recommended. Operating environments and the unit of encipherment are covered. The implementation of cryptographic methods in communication security is explained for three levels -link, session, and private. Also addressed are file security cryptography, data accuracy considerations, and the impact of lost keys. Diagrams and an index are included. The appendixes contain a summary of data security features implemented in IBM products and a list of related IBM publications.