Data security and compaction techniques
Date
1980
Authors
Murphy, Timothy Fitzgerald
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Abstract
This thesis studies two common problems faced by computer analysts.
The first is data compaction; often this is required for economic reasons or to make best use of scarce external storage and associated interfaces.
The second problem is that of protecting data which has been obtained by unauthorized persons from exposure, by cyphering or encryption. This exposure can be accidental, such as a computer tape being lost, or a deliberate interception of a cyphered transmission.
The basic aim of this thesis is to examine the interrelation between compaction and security cyphering. While a connection appears probable little work has been done on this subject.
A number of data compaction techniques are evaluated and it is shown that data compaction is justified on modern computer systems. Theoretical limits to data compaction are given and, generally lower, practical limits are discussed.
The effect of data compaction on cypher security is demonstrated theoretically. Several modern computer cypher techniques are reviewed; data compaction is shown to be required to increase their security. Some weaknesses in modern computer security are reviewed and methods are given to increase this security. Methods of compacting computer data prior to encryption are given.
Computer Programs are supplied in the appendices for security encryption.