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<div class="moz-cite-prefix">David,<br>
I was trying to suggest that we need not restrict Fixity Value to
simplistic representations, nor was it necessarily the case that a
Fixity Value would necessarily be a simple, uncomplicated token.<br>
<br>
I'll take your questions in order: <br>
<h2>Ciphertext and Fixity<br>
</h2>
I was speculating that no examples of Fixity, either as
(processing/derivation/algorithmic) Information or specific Fixity
Values are necessarily well represented by our current
understanding of data protection methods. <br>
<br>
In that spirit, let me suggest that Fixity Values need not be
smaller than their source objects. A Fixity Value could be a
protected copy of the source object. Digital storage has become
progressively cheaper over the past 7 decades, and future storage
architectures (perhaps even current ones) may make storing secured
copies cheaper than any other method. <br>
<br>
In other words, we need not restrict Fixity Values to minimal
tokens representing some larger bitfile. We all know that there is
no Hash or equivalent token that cannot be duplicative of a
non-equivalent source text. The Fixity Value could be a (perhaps
but not necessarily compressed) encrypted form of the source
object. It might be larger than that source object, but by
encrypting it Fixity is doubly protected, first as Ciphertext,
secondarily as a comparand for the original source. Furthermore,
while it's wild speculation at the moment, lossless compression
with encryption could in fact result in something smaller than the
original. If the Fixity Information describes compression or
encryption or both as the process by which a Fixity value is
created, then the resulting Fixity Value is in fact a copy of the
whole initial object. In that situation, the initial object could
conceivably only be materialized in its external versions (i.e.
DIPs or other uncontrolled remote copies).<br>
<br>
<h2>Functional Logic expression</h2>
The term was perhaps poorly chosen. I used the term Functional
logic to label any method that provides for algorithms to be
encoded in computer software as any composition of declarative (or
Propositional or Calculus) and procedural (or Algebraic)
expressions. I use the term here to broaden my speculation that
certain source objects would be protected algorithmically. I
recalled discussions in which we've declared Fixity to be a
broadly scoped concept entailing protections for essentially
anything in or out of an AIP that the repository needs to protect.
A functional logic expression is one that permits expression of
an intended function or algorithm by combining the two in a single
program text. I did some experiments with this idea in the 70s,
using predicate calculus expressions as declarative substitutes
for Fortran IF-THEN-ELSE constructions. In such a protocol, a
Fixity Value could be a logical expression, conceivably embodying
some procedural code. <br>
<br>
It's a trivial example, but if a Table of logarithms were an
object to be preserved, the Fixity Information could be a general
method for interpreting formulae, and th Fixity Value might be the
formula that generated it. <br>
<br>
<h2> Not (too) wild, but speculation I concede.<br>
</h2>
We don't know today how technology will evolve but we can imagine
possible futures, including Quantum methods for performing
arithmetic and logical functions in ways not easily accommodated
by standard Turing architectures. I'm sure that there are better
ways to describe both of these concepts, but I'm not claiming that
these things could be implemented or even if they would be
desirable. Just trying to show that current methods should not
represent boundaries in our descriptions of Fixity.<br>
<br>
Terry<br>
<br>
On 4/29/2017 6:01 PM, PTAB Secretariat wrote:<br>
</div>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext;mso-fareast-language:EN-US">Terry<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext;mso-fareast-language:EN-US">Glad
to add any examples but isn’t ciphertext encryption rather
than checking about changes – or do you mean that one can
later on re-encrypt the object and compare with the saved
encrypted value?<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext;mso-fareast-language:EN-US">What
do you mean by “</span>functional logic expression
satisfying the Fixity Information”?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">..David<span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"
moz-do-not-send="true"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext;mso-fareast-language:EN-US"><o:p> </o:p></span></a></p>
<span style="mso-bookmark:_MailEndCompose"></span>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext"
lang="EN-US">From:</span></b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:windowtext"
lang="EN-US"> ISO Primary TDR Accreditation Board [<a
class="moz-txt-link-freetext"
href="mailto:ISO-PTAB@JISCMAIL.AC.UK">mailto:ISO-PTAB@JISCMAIL.AC.UK</a>]
<b>On Behalf Of </b>Terry Longstreth<br>
<b>Sent:</b> 29 April 2017 14:48<br>
<b>To:</b> <a class="moz-txt-link-abbreviated"
href="mailto:ISO-PTAB@JISCMAIL.AC.UK">ISO-PTAB@JISCMAIL.AC.UK</a><br>
<b>Subject:</b> Re: Fixity - again<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">I agree, but extend the examples to
include 'ciphertext or functional logic expression
satisfying the Fixity Information'<br>
<br>
On 4/29/2017 9:30 AM, Robert Downs wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<div>
<div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt">David
-<o:p></o:p></p>
</div>
<p class="MsoNormal">These look good. In the
definition of Fixity Information, I suggest
replacing "check" with "verify". Also, in the
sentence, "<span
style="font-size:10.0pt;font-family:"Courier
New",serif">Fixity Values may include
Cyclical Redundancy Check (CRC) codes or digests
etc ..," </span><o:p></o:p></p>
</div>
<p class="MsoNormal" style="margin-bottom:12.0pt">I
suggest adding "checksums", and replacing "digests"
with "message digests" so that it reads as "Fixity
Values may include Cyclical Redundancy Check (CRC)
codes, checksums, or message digests, etc ...".<o:p></o:p></p>
</div>
<p class="MsoNormal" style="margin-bottom:12.0pt">Thanks,<o:p></o:p></p>
</div>
<p class="MsoNormal">Bob <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><br clear="all">
<o:p></o:p></p>
<div>
<div>
<div>
<p class="MsoNormal">Robert R. Downs, PhD<br>
Senior Digital Archivist and Senior Staff Associate
Officer of Research<br>
Acting Head of Cyberinfrastructure and Informatics
Research and Development<br>
Center for International Earth Science Information
Network (CIESIN),<br>
The Earth Institute, Columbia University<br>
P.O. Box 1000, 61 Route 9W, Palisades, NY 10964 USA<br>
Voice: 845-365-8985; fax: 845-365-8922<br>
E-mail: <a href="mailto:rdowns@ciesin.columbia.edu"
target="_blank" moz-do-not-send="true">rdowns@ciesin.columbia.edu</a><br>
Columbia University CIESIN Web site: <a
href="http://www.ciesin.columbia.edu"
target="_blank" moz-do-not-send="true">http://www.ciesin.columbia.edu</a><br>
ORCID: 0000-0002-8595-5134<o:p></o:p></p>
</div>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On Sat, Apr 29, 2017 at 7:12 AM,
David Giaretta <<a href="mailto:david@giaretta.org"
target="_blank" moz-do-not-send="true">david@giaretta.org</a>>
wrote:<o:p></o:p></p>
<blockquote style="border:none;border-left:solid #CCCCCC
1.0pt;padding:0cm 0cm 0cm
6.0pt;margin-left:4.8pt;margin-right:0cm">
<div>
<div>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">See
<a
href="http://review.oais.info/show_bug.cgi?id=18"
target="_blank" moz-do-not-send="true">http://review.oais.info/show_bug.cgi?id=18</a>
<o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">The
new comment is:<o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">After
some exchanges of emails I have the following
suggestions to take into account:</span><o:p></o:p></p>
<p class="m-1280572966275357738msolistparagraph"><span
style="font-size:10.0pt;font-family:"Courier New",serif">1.</span><span
style="font-size:7.0pt"> </span><span
style="font-size:10.0pt;font-family:"Courier
New",serif">the Content Information must
include a Representation (Information) Network,
which may need to be extended - thereby changing
the Fixity Info; an added complication is that
part or all of the RepInfoNet may be held in
another repository.</span><o:p></o:p></p>
<p class="m-1280572966275357738msolistparagraph"><span
style="font-size:10.0pt;font-family:"Courier New",serif">2.</span><span
style="font-size:7.0pt"> </span><span
style="font-size:10.0pt;font-family:"Courier
New",serif">we don't want to specify an
implementation - but I hope some examples will
be OK</span><o:p></o:p></p>
<p class="m-1280572966275357738msolistparagraph"><span
style="font-size:10.0pt;font-family:"Courier New",serif">3.</span><span
style="font-size:7.0pt"> </span><span
style="font-size:10.0pt;font-family:"Courier
New",serif">we probably want to point out
that although Fixity Information is about
Content Information, similar mechanisms can be
used for all data files</span><o:p></o:p></p>
<p class="m-1280572966275357738msolistparagraph"><span
style="font-size:10.0pt;font-family:"Courier New",serif">4.</span><span
style="font-size:7.0pt"> </span><span
style="font-size:10.0pt;font-family:"Courier
New",serif">we want to make it clear that
Fixity Information is more than a simple CRC or
digest</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">The
suggested change is:</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">From:</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">Fixity
Information: The information which documents the
mechanisms that ensure that the Content
Information object has not been altered in an
undocumented manner. An example is a Cyclical
Redundancy Check (CRC) code for a file.</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">To:</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">Fixity
Information: The information which documents the
process(es) that can be used to check, using the
Fixity Value(s) created at an earlier time, and
included as part of the Fixity Information, that
the Content Information object (the Content Data
Object and its Representation (Information)
Network) has not been altered in an undocumented
manner. The Fixity Information must define what
happens if the Representation Information is
enhanced to ensure that the Designated Community
can understand and use the Content Data Object.</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">Also
add new definition:</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">The
Fixity Values are created based on the Content
Data Object and the Representation (Information)
Network held by the repository, including the
pointers to Representation Information held
remotely (if any). </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">Also
add the following discussion in section
4.2.1.4.2:</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">The
Fixity Information will change when the
Representation Information must be enhanced to
ensure the Designated Community can understand
and use the Content Data Object. The process(es)
described by the Fixity Information could
include, for example, one or more of:</span><o:p></o:p></p>
<p class="m-1280572966275357738msolistparagraph"
style="margin-left:64.0pt"><span
style="font-size:10.0pt;font-family:"Courier
New",serif">1.</span><span
style="font-size:7.0pt"> </span><span
style="font-size:10.0pt;font-family:"Courier
New",serif">immediately producing new AIP
Editions(?) with updated PDI </span><o:p></o:p></p>
<p class="m-1280572966275357738msolistparagraph"
style="margin-left:64.0pt"><span
style="font-size:10.0pt;font-family:"Courier
New",serif">2.</span><span
style="font-size:7.0pt"> </span><span
style="font-size:10.0pt;font-family:"Courier
New",serif">delay producing new AIP
Editions until convenient, before which time the
links between the additional Representation
Information and the relevant AIPs are maintained
using a separate mechanism by the repository,
without changing the PDI</span><o:p></o:p></p>
<p class="m-1280572966275357738msolistparagraph"
style="margin-left:64.0pt"><span
style="font-size:10.0pt;font-family:"Courier
New",serif">3.</span><span
style="font-size:7.0pt"> </span><span
style="font-size:10.0pt;font-family:"Courier
New",serif">delegating responsibilities for
an individual piece of Representation
Information to the preservation mechanisms of
the repository which holds it; for example each
piece of Representation Information could be
preserved within an AIP for which that
Representation Information is the "original
target of preservation".</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">Fixity
Values may include Cyclical Redundancy Check
(CRC) codes or digests etc for the individual
Digital Objects or detailed physical
specifications for Physical Objects. Fixity
Values may also be derived from any of the
standard mechanism for tracking and verifying
the validity of all Data Objects within the
Archive, for example, CRCs could be maintained
for every individual data file. </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">We
should also correct "Table 4-1: Examples of
PDI"</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">-------</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">Not
sure if AIP Editions is right in this instance
because the definition says:</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">AIP
Edition: An AIP whose Content Information or
Preservation Description Information has been
upgraded or improved with the intent not to
preserve information, but to increase or improve
it. An AIP edition is not considered to be the
result of a Migration</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif"> </span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="font-size:10.0pt;font-family:"Courier New",serif">Since
the above if a change to preserve the Content
Information then either we would need to change
the definition of AIP Edition or we would need
to define a new term. AIP Version is about
Migration.</span><o:p></o:p></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="color:#888888"> <o:p></o:p></span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="color:#888888"> <o:p></o:p></span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="color:#888888"> <o:p></o:p></span></p>
<p class="MsoNormal"
style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span
style="color:#888888">..David<o:p></o:p></span></p>
</div>
</div>
</blockquote>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</blockquote>
<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
<div>
<p class="MsoNormal">-- <br>
<img style="width:3.5347in;height:1.4791in"
id="_x0000_i1025"
src="cid:part8.68A0A565.62C806AA@comcast.net" width="339"
height="142" border="0"><o:p></o:p></p>
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