Information Technology Reference
In-Depth Information
for creating and preserving Provenance Information from the point of Ingest,
however earlier Provenance Information should be provided by the Producer.
Provenance Information adds to the evidence to support Authenticity.
The concept of authenticity as defined by OAIS requires a detailed analysis on the
basis of the rich literature in the sector and of the main outputs of research projects
like InterPARES, as mentioned in the CASPAR position paper [
24
].
There are some basic assumptions to be considered before entering into a detailed
analysis. First of all, authenticity cannot be evaluated by means of a boolean
flag telling us whether a document is authentic or not. In other words there are
degrees of confidence about the authenticity of the digital resources: certainty about
authenticity is a goal, but one which is unlikely to be fully met.
In the case of physical objects such as a parchment, one can look at physical
composition, confirm the age with carbon dating, and compare to similar documents.
The identity and integrity concepts can fairly obviously be applied to such physical
objects which cannot be readily copied of changed without leaving some trace. What
is so different with digital objects? What process of evaluation and what sort of tools
must be developed?
One fundamental issue arises from the basic points about why digital objects are
different, namely that one cannot really ensure the ability to maintain the original
bits or even to provide methods for easily evaluating whether they are the origi-
nal. At the very least one has to copy the bits from one medium to another. How
can we be sure that the copy was done correctly? Here we want to guard against
both accidental changes as well as changes made on purpose, perhaps for nefarious
purposes.
Other issues arise from the basic preservation strategies described in
Chap. 12
.
Adding Representation Information, maintaining access and emulation do not
require any changes to the bit sequences of the digital object, nor do the types of
migration described as refreshment of replication. Repackaging requires changes in
the packaging but not of the digital object of interest. In all these cases we can use,
for example, digests as the evidence about the lack of change in the bit sequences.
Only the Transformation preservation technique (
Sect. 12.3.1
) implies a change
in the digital object and therefore the use of digests will not apply. As an example
of Transformation, consider a WordStar version of a document which may be con-
verted into Word 2007 format in order to ensure that this (Rendered) Digital Object
can continue to be rendered. Is it an authentic version (whatever that means in this
context)? We will return to this a little later in Sect.
13.6
.
Looking in more detail at the use of digests, one compares the digest of the
original to the copy and then one can be fairly, but not completely, certain things
are as they should be. It would be alright if one has access to the original and could
calculate the digest oneself, but this is rarely the case. So where does the digest come
from, and how can we be sure it is indeed the digest i.e. that it is what it purports to
be? This sounds like a familiar question - we have come round in a circle! This is
of course another example of recursion which we discussed in
Sect. 3.3
.
So how does this help us with the Authenticity of digital objects? It seems that
the key points are that
