NCJ Number
58052
Date Published
1977
Length
142 pages
Annotation
FOLLOWING AN OVERVIEW OF THE CHARACTERISTICS OF DIGITAL COMMUNICATIONS SYSTEMS, VARIOUS WAYS TO ACHIEVE DATA SECURITY THROUGH ENCRYPTION ARE DESCRIBED. THE LUCIFER DEVICE, WHICH USES A COMPLEX ALGORITHM, IS RECOMMENDED.
Abstract
SENSITIVE DATA MUST BE PROTECTED FROM BOTH ACCIDENTAL AND DELIBERATE SECURITY VIOLATIONS AND FROM BOTH PASSIVE AND ACTIVE THREATS. A PASSIVE INFILTRATION THREAT ATTEMPTS TO LISTEN TO THE INFORMATION TRANSFER PROCESS WITHOUT DISRUPTING OR CHANGING THE DATA, USUALLY THROUGH WIRE TAPPING. ACTIVE INFILTRATION ATTEMPTS TO MODIFY DATA. SINCE COMMUNICATIONS LINKS CANNOT BE MADE COMPLETELY SECURE A CRYPTOGRAPHIC SYSTEM IS NEEDED. MANY BUSINESSES FAIL TO REALIZE HOW EASY IT IS FOR A PERSON WITH A BASIC KNOWLEDGE OF ENCRYPTION ALGORITHMS TO DECODE MESSAGES. FOR THIS REASON SIMPLE ADD-ON ENCRYPTION SYSTEMS WHICH PERFORM ONLY SIMPLE TRANSFORMATIONS DO NOT OFFER GOOD SECURITY. OFTEN THEY MAY REQUIRES AS FEW AS 20 CHARACTERS OF CLEAR TEXT AND THE MATCHING 20 CHARACTERS OF ENCRYPTED TEXT TO RECOVER THE KEY. THE MOST EFFECTIVE COMPUTER SECURITY SOFTWARE SYSTEMS USE THE MANIPULATION OF ALGORITHMS TO DEVELOPE A 'CIPHER,' THAT IS A SUBSTITUTION, TRANSPOSITION, OR ADDITION OF CHARACTERS. ONE OF THE MOST SECURE IS THE LUCIFER DEVICE, WHICH USES REPEATED SUBSTITUTIONS AND TRANSFORMATIONS ON A BLOCK OF 16 8-BIT CHARACTERS FOR A TOTAL BLOCK LENGTH OF 128 BITS USING A KEY OF THE SAME LENGTH. THIS SYSTEM IS THE BASIS FOR THE FEDERAL ENCRYPTION STANDARD (FEDERAL INFORMATION PROCESSING STANDARDS PUB. 46). EXAMPLES SHOW THE USE OF THIS PROTOCOL WITH BOTH ASYNCHRONOUSAND SYNCHRONOUS SYSTEMS. THIS WELL-ILLUSTRATED DISCUSSION IS RELATIVELY NONTECHNICAL AND CONTAINS CHARTS, ILLUSTRATIONS, EXAMPLES, AND REFERENCES. (GLR)