Subject: Data Splitting

From: "Santosh Chokhani" <[email-masked]>
Date: Wed, 21 Apr 2004 12:04:30 -0400

I have been looking at some of the work done in this area.  It seems that a
pure data splitting technique may not be practical.  There are couple of
problems.  For a large amount of data, how would you calculate the prime and
then coefficients.  This may be computationally extremely complex or
infeasible, i.e. may take the time of the life of the data to split the
data.
 
Even a 2 of 2 scheme using exclusive OR will be problem since finding a
random stream the size of the data will be next to impossible  If you had
smaller seed then, you get into the issue of one of the TAA being able to
guess the stream since the entropy of the stream is low.  We could explore
the issue of how long the random seed should be for long-term archive.
 
If you use other techniques listed in the literature; they all relate to
using keys and encryption (for secret sharing).  These will not be
attractive because if we were to use keys, we should use time stamp which is
an integrity and authentication mechanism.
 
We have also thought about doing the splitting of hash of the document.
This approach is workable, but has the following disadvantages:  1. It
requires the submitter or someone else to maintain the document; 2. The
original hash needs to be large enough to cover the archival period or the
refresh requires the participation of the submitter/actual document holder.
 
These are some preliminary thoughts.  I will continue to analyze the
approaches and issues surrounding data splitting.
 
In the mean time, your thoughts and analysis on the topics and your critique
the analysis above are welcome.

Santosh Chokhani 
Orion Security Solutions, Inc. 
1489 Chain Bridge Road, Suite 300 
McLean, Virginia 22101 
(703) 917-0060  Ext. 35 (voice) 
(703) 917-0260 (Fax) 
[email-masked] 
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