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High Performance Voting for Data Encription Standard Engine Data Integrity and Reliability

IP.com Disclosure Number: IPCOM000106443D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 123K

Publishing Venue

IBM

Related People

Butter, AS: AUTHOR [+4]

Abstract

Disclosed is the use of data compare and voting logic which function as a high speed select mechanism for picking the correct result from three (3) parallel Data Encryption Standard (DES) [*] hardware functions. This concept creates a highly reliable and available DES Engine, without any degradation in DES processing performance.

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High Performance Voting for Data Encription Standard Engine Data Integrity and Reliability

      Disclosed is the use of data compare and voting logic which
function as a high speed select mechanism for picking the correct
result from three (3) parallel Data Encryption Standard (DES) [*]
hardware functions.  This concept creates a highly reliable and
available DES Engine, without any degradation in DES processing
performance.

      In the environment of data processing, especially where large
data transfers occur across networks, high speed data encryption has
become commonplace for security reasons.  For DES applications, data
integrity is the primary hardware requirement, based on the fact that
the users must always have access to their data.  If a faulty DES
Engine is allowed to operate on any data, results are almost always
disastrous.  It is for this reason that DES must be 100% reliable and
available.  The voting scheme described shows how to achieve such
high availability and reliability.

      In hardware implementations that perform complex data
manipulation, normal error checking methods, such as check bits and
parity, become impractical.  This is mainly due to the tremendous
amount of complex circuits needed to maintain the correct "check bit"
values throughout the path that requires the error detection.
Alternative methods, such as logical redundancy, are much more
practical in the case of DES Data checking.

      Most redundant implementations simply compare the results of
two identical functions of a particular design to detect errors.  In
the new scheme, a third DES function is implemented to provide
superior reliability, along with enhanced error detection.  This
scheme is referred to as "voting", since the compare and check logic
vote on which, if any, of the DES functions has generated bad data,
and then degate their data from the output path.

      The data output by the DES Engine is selected by compare and
voting logic acting on three separate busses, one from each of the
DES functions as seen in Fig. 1.  Results of each DES function are
bit compared using common XOR (exclusive or) logic.  The voting
portion of the logic constantly receives the result of each bit
compare and takes action based on these results.  Selection of a
correct result occurs without delaying the delivery of the output
data to the next destination.  This selection occurs according to the
truth table in Fig. 1.

      The truth table contains three input terms X, Y, and Z, and
five output terms 1, 2, 3, ERROR and DAMAGED.  A one (1) appearing in
any of the X, Y, or Z columns reflects good compare results, a zero
(0) reflects incorrect compare results.  A one (1) in either the 1 or
2 output terms reflects the co...