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Browse Prior Art Database

Encryption Method

IP.com Disclosure Number: IPCOM000113843D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 97K

Publishing Venue

IBM

Related People

Swingle, P: AUTHOR

Abstract

Disclosed is a method to encrypt information for storage within, or for sending from, a computer, so that the information cannot be understood by someone without the appropriate key. This method takes advantage of run length coding, Huffman coding, and pseudo-random number generators to create a code that is very nearly unbreakable. This method combines existing techniques in a specific way to create a secure encryption and decryption method while using relatively modest computer resources.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Encryption Method

      Disclosed is a method to encrypt information for storage
within, or for sending from, a computer, so that the information
cannot be understood by someone without the appropriate key.  This
method takes advantage of run length coding, Huffman coding, and
pseudo-random number generators to create a code that is very nearly
unbreakable.  This method combines existing techniques in a specific
way to create a secure encryption and decryption method while using
relatively modest computer resources.

      In the implementation of this method, the text is first run
length coded with any string of more than three characters in a row
being replaced by a three-character string.  Next, the resulting
string of characters is Huffman coded so that the most common
characters are encoded into shorter bit sequences.  Multiple
pseudo-random number generators, using diverse techniques, are each
started with their own seeds.   Each generator keeps its own seed for
the next round.   The results of all of the pseudo-random number
generators and the next eight bits of the Huffman code are
exclusive-ORed to produce a character of the encoded stream, which is
either stored or transmitted.  The reverse process decrypts the
stream at the other end of the transmission or storage channel.  The
run length coding and Huffman coding together create a stream of bits
that is difficult to recognize as clear text, making it much more
difficult to try all combinations of keys in an exhaustive search.

      Using multiple pseudo-random number generators solves several
other problems of existing methods.  First, as presently used,
pseudo-random number generators exhibit the weaknesses of repeating
number sequences after relatively short intervals, and of having
sequences of less than random numbers.  With the presently disclosed
method, the use of multiple kinds of generators, each of which uses
different generation techniques, the likelihood of all the generators
having the same kind of weakness in the same area is very small.  The
key used by this method is a string of seeds for the different
pseudo-random number generators.  The decryption process is
essentially the reverse of the encryption process.  An additional
measure of security is provided by the fact that the Huffman code
does not need to be transmitted.  For any given environment, the
statistics on letter usage are stable enough that the Huffman code
can be a constant.  Different keys may be used for different
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