Information Technology Reference
In-Depth Information
Having these definitions one can then go on to define the concept which the
discussion earlier in this Chapter suggests, namely something which comes into
play when digital objects are transformed:
Transformational Information Property:
An Information Property whose
preservation is regarded as being necessary but not sufficient to verify that the
Non-Reversible Transformationhas adequately preserved information content.
This could be important as contributing to evidenceabout Authenticity. Such
Information Properties will need to be associated with specific Representation
Information, including Semantic Information, to denote how they are encoded
and what they mean. (Note that the term 'significant property', which has various
definitions in the literature, is sometimes used in a way that is consistent with it
being a Transformational Information Property).
Note that if the Transformation were reversible then it is reasonable to take it
that no information is lost. It is for this reason that the above definition focuses on
non-reversible transformations. For completeness the definitions of the reversible
and non-reversible transformations are as follows:
Reversible Transformation:
A Transformation in which the new represen-
tation defines a set (or a subset) of resulting entities that are equivalent to the
resulting entities defined by the original representation. This means that there
is a one-to-one mapping back to the original representation and its set of base
entities.
Non-Reversible Transformation:
A Transformation which cannot be guaran-
teed to be a Reversible Transformation
.
The important point is that the definition of non-reversible is drawn as broadly as
possible.
Having this theoretical underpinning, we can now describe a tool which brings
together the ideas about authenticity and significant properties, showing some real
examples.
13.7 Prototype Authenticity Evidence Capture Tool
In order to delve into the practicalities we now describe in some detail an
Authenticity Management tool created in the CASPAR project. This should make
clear some of the design considerations needed to be taken into account when one
deals with evidence about authenticity, where one must also be concerned about the
authenticity of that evidence (recursion again!). It also allows us to describe in more
detail the practical examples in Sect.
13.7.6
.
This tool imports an XML formatted set of Authenticity Protocols (AP), an AP
defining a set of procedures that should be undertaken by the capturer. Each AP
is made up of Authenticity Steps (AS). An Authenticity Step will define specific
PDI information required for capturing and imposing questions on the capturer,
for instance by asking what standards or methodologies have been followed and
detailing other criteria that must be satisfied. Each step is executed by an actor,
