Establishing and Verifying Fixity of Archived Web Pages

Establishing and Verifying
Fixity of Archived Web
Pages
Mohamed Aturban
Old Dominion University
Advisors:
Dr. Michele C. Weigle and Dr. Michael L. Nelson
JCDL 2018 Doctoral Consortium
June 3, 2018
JCDL 2018 Doctoral Consortium, 2018-06-03 @maturban1

2
This is what climate.nasa.gov/vital-signs/carbon-dioxide/
looks like right now

3
The Internet Archive allows us to view
previous versions (mementos) of that page

4
http://web.archive.org/web/*/https://climate.nasa.gov/vital-signs/carbon-dioxide/

https://web.archive.org/web/20160708040004/https://climate.nasa.gov/vital-signs/carbon-dioxide/
An archived page (memento) from July 2016

6
The page in other web archives
for a full list of public web archives, see: http://labs.mementoweb.org/aggregator_config/archivelist.xml
Typical archive URI construction:
archive.example.org/SomeString/climate.nasa.gov/vital-signs/carbon-dioxide
(2,782)
(48)
(3)
(12)
(0)
(0)
(3)
The number of mementos
available in the archive

7
What if we checked these archives?
What if they all agree?
Would you trust the results?
climate.nasa.gov/vital-signs/carbon-dioxide/
michaelsevilwayback/web/*/climate.nasa.gov/vital-signs/carbon-dioxide/

8
The web page is archived by Michael’s Evil
Wayback in July 2017
Michaelsevilwayback/web/20170717185130/https://climate.nasa.gov/vital-signs/carbon-dioxide/

9
Replaying the same memento in October 2017,
we got a different CO2
Michaelsevilwayback/web/20170717185130/https://climate.nasa.gov/vital-signs/carbon-dioxide/

10
Which one is the real memento?
July 2017 October 2017
• How to ensure that a memento has remained unaltered
since the time it was captured by the archive?
Michael_evil_wayback/web/20170717185130/https://climate.nasa.gov/vital-signs/carbon-dioxide/ Michael_evil_wayback/web/20170717185130/https://climate.nasa.gov/vital-signs/carbon-dioxide/

It is important to verify fixity of
archived resources
• Web archives will be the only evidence of what was in the live web
• For example, The Data Refuge project is an attempt to preserve
federal climate and environmental data
- But in the future, how to verify archived copies in this specific
archive have remained unchanged

12
Do archived pages change?
Time
Live
Web
t0 t9 t14

13
TimeLive
Web
TimeArchive URI-M1 URI-M2 URI-M3 URI-M4 URI-M5
t0 t2 t4 t6 t9 t14 t16 t18

14
TimeLive
Web
TimeArchive
Replay Time
URI-M1 URI-M2 URI-M3 URI-M4 URI-M5
URI-M2
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18

15
TimeLive
Web
TimeArchive
Replay Time
URI-M2
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18
When replaying URI-M2 at different points in
time, will we get the same content?

16
TimeLive
Web
TimeArchive
Replay Time
URI-M2 URI-M2
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18

17
TimeLive
Web
TimeArchive
Replay Time
URI-M2 URI-M2
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18

18
TimeLive
Web
TimeArchive
Replay Time
URI-M2 URI-M2 URI-M2
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18

19
TimeLive
Web
TimeArchive
Replay Time
Our study shows that we are not always
presented with the same archived content!
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18

20
Cryptographic hashes to create
fixity information
• Common hash algorithms (e.g., MD5, SHA256):
A small change in the input à a large change in the output
My name is Mohamed Aturban, a
graduate student in the
Department of Computer Science
at Old Dominion University. I
am attending the 18th ACM/IEEE
Joint Conference on Digital
Libraries (JCDL), 2018.
SHA256
9801 1510 87e1 6d6b
ddb9 e6b0 09fd b723
abe5 1fea b548 0914
a130 6325 5ae4 6caa
SHA256
5d4d b590 605c 9023
000d 6622 6004 534f
e84a 5549 d535 f91e
cdf4 4952 5c1a 37cf

SimHash:
A small change in the input à
a small change in the output
SimHash
ed646a9efbc77705
SimHash
ed646a9efbc77305
https://github.com/leonsim/simhash
• We can not use SimHash on archived pages because small changes matter

22
SimHash:
large changes in the input à
large changes in the output
SimHash
ed646a9efbc77705
My name is Sawood Alam, a
SimHash
ed666bdefbc77205

23
Is there an existing hashing
function suitable for mementos?
Web archive Hash value
?
an archive-aware
hashing function

24
Generate hashes on a web page
• Compute a hash value on the downloaded HTML content
% curl -s https://climate.nasa.gov/vital-signs/carbon-dioxide/
| shasum -a 256
17710fd38d908a3cd124510f26adaec67e57e3f1d3aec1209c4ad4efbe2c035d
Compute SHA256 hash
Download the page

Time
HTML
content is
downloaded
e834 c71a efda 284f e03a 4eed 4e8c b78e
a581 537b a888 4aec ec29 bd2d 66cb f521
SHA256
Hash
HTML
content is
downloaded
fc90 88b3 a614 a588 40bd 5387 d93c 16be
824c d2bb b3fa b173 f93f a57d 241a 3790
SHA256
Hash
August 2017
October 2017
The archived page has been tampered with by changing the value of COSeptember 2017
2
25
• Compare the current hash and the previous hash
To verify fixity
Hashes are NOT identical à the page has changed!
http://ws-dl.blogspot.com/2017/12/2017-12-11-difficulties-in-timestamping.html

26
What if an image has changed?
Computing hashes on only HTML content will
NOT detect changes

27
Potential solution: include all
resources in hash calculation
https://web.archive.org/web/20170717184643/https://climate.nasa.gov/vital-signs/carbon-dioxide/
• 201 images
• 19 JavaScript files
• 3 CSS files
• Main HTML file
A single aggregated
hash value
www.gwern.net/Timestamping (Existing tools for generating a hash value on a composite archived page )
has
A composite memento
https://ws-dl.blogspot.com/2015/12/2015-12-08-evaluating-temporal.html
http://ws-dl.blogspot.com/2017/12/2017-12-11-difficulties-in-timestamping.html
Turns out it is hard to get
repeatable hashes on
composite mementos

28
What is a composite memento?
“A composite memento is a root resource
such as an HTML web page and all of the
embedded resources (images, CSS, etc.)
required for a complete presentation”
http://ws-dl.blogspot.com/2015/12/2015-12-08-evaluating-temporal.html
WADL 2018, 2018-06-06 @maturban1

29
Research Questions
R.Q.1 How can we construct an archive-
aware hashing function for generating
repeatable fixity information on archived
web pages?
R.Q.2 How to develop an approach to use
this information to verify fixity and detect
changes in archived resources over time?

30
Dissertation plan
Literature review
Identify types of changes and define requirements for generating
repeatable hashes
Build a probability model of rendering the same archived pages
PhD Defense
Study different existing data models for serializing fixity information
and select one
Implement different services to:
- Generate fixity information
- Publish fixity information on the web
- Verify archived resources
Evaluate the framework
Finish writing the dissertation
Define the framework’s structure of verifying fixity
Analyze the same archived pages downloaded at different times
PreliminaryworkFuturework

31
Related Work
TRAC (2007)
Establishing trusted archives
- TRAC not for playback
Lerner et al. (2017)
Vulnerabilities
- Discovered four vulnerabilities in the
Internet Archive’s Wayback Machine
J. Cushman et al. (2017)
More potential threats
- Demonstrate potential threats in
web archives
Rosenthal et al. (2005)
Threats
- Described several threats against
digital preservation systems
Juan Benet (2017)
Multihash
- Self identifying hashes for IPFS
OpenTimestamps, OriginStamp,
Gipp (2015, 2016), and
Chainpoint
Trusted timestamps in
Blockchain
- Not suitable for composite
mementos
T. Kuhn et al. (2014)
Trusty URI
- A URI that contains a hash value of
the content it identifies
P. Maniatis et al. (2005)
Distributed copies of
archived resources
- The scope and content are
narrowly defined

32
Dissertation plan
Literature review
repeatable hashes
PhD Defense
and select one

33
Archives transform original content to
appropriately replay mementos in a user’s
browser
• Add banners
• Rewrite links to point to the archive, not to the
live web
• Modify HTML code to convey metadata
• Apply some policies for security (e.g., block
some content)
• Provide the content in different format (e.g., ZIP
and screenshots)
Transformation examples:

34
Archives add banners
• To convey information like the number of mementos and
inform users that what they are viewing is from the archive
• Banners change à different hashes
Replayed in 2016 (43 mementos) Replayed in 2017 (49 mementos)
http://webarchive.proni.gov.uk/20150826163149/http://www.ulster.ac.uk

35
Archives rewrite links to embedded
resources
web.archive.org/web/19961120150251 /http://www.usnews.com:80/
http://web.archive.org/web/19970725063110im_/http://www.usnews.com:80/usnews/GRAPHICS/logo.gif
http://www.usnews.com:80/usnews/GRAPHICS/logo.gif

36
Live web resources linked from archives
• Resources from the live web are expected to change à different hashes
• Based on feedback from Lerner et al., IA solved this issue with Content-
Security-Policy HTTP header, but the problem might still occur in other archives
http://ws-dl.blogspot.com/2012/10/2012-10-10-zombies-in-archives.html
Archived in 2008
The ad is from 2012
This memento was
replayed in 2012
A. Lerner, T. Kohno, and F. Roesner. Rewriting history: Changing the archived web from the present. In Proceedings of the 16th ACM conference on Computer
and Communications Security (CCS), pages 1741–1755, 2017.

37
Caches will temporarily hide changes
in the playback à different hashes
% date Mon Oct 2 01:15:18 EDT 2017
% curl -s http://web.archive.org/web/20130724144801/htt
p://www.cnn.com/ | md5
477b6d923cbb7bf9675a0d2feb37afd3
% date Mon Oct 2 01:16:29 EDT 2017
% date Mon Oct 2 01:19:31 EDT 2017
% date Mon Oct 2 02:10:24 EDT 2017
dda6a9bf091d412cbdc2226ce3eb1059
X-Page-Cache: MISS
X-Page-Cache: HIT
X-Page-Cache: MISS
X-Page-Cache: HIT

38
Dynamic content by JS à different hashes

39

40

41
A large number of
mementos are
unavailable

42
A resource selected randomly by
JavaScript
https://www.webharvest.gov/congress112th/20130119060624/http://www.fws.gov/

43
JavaScript

44
JavaScript

45
JavaScript
function random_imglink(){
myimages[1]="/congress112th/20130119060624/http://www.fws.g
ov/home/feature/home-banner/open-spaces/bannerbluemnt.jpg";
ov/home/feature/home-banner/open-spaces/bannereagle.jpg";
ov/home/feature/home-banner/open-spaces/bannertiger.jpg";
var ry=Math.floor(Math.random(1)*myimages.length)
if (ry==0)
ry=1
document.write('<a href='+'"'+imagelinks[ry]+'"'+'><img
src="'+myimages[ry]+'" border="0" alt="The Open Spaces
Blog. A Talk on the Wild Side. Click to Read"></a>')
}

46
Changes in TimeMaps
TimeLive
Web
TimeArchive
Replay Time
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18
A TimeMap = a list of available mementos =
URI-M1
URI-M2
URI-M3
URI-M4
URI-M5

47
The requested memento is unavailable
TimeLive
Web
TimeArchive
Replay Time
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18
X

48
Mementos with the same content
are not available either
TimeLive
Web
TimeArchive
Replay Time
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18
X
X X

49
URI-M2 redirects to other memento (URI-M4)
which has different content
TimeLive
Web
TimeArchive
Replay Time
t0 t2 t4 t5 t6 t9 t14 t16 t17 t18
XX X
302 Redirect

HTML
content is
downloaded
d13a 247e 872e 11d5 64f4 b49a 24d8 275c
a09f ee8d 48c0 0345 f458 5d4b 7ec3 e663
Hash
HTML
content is
downloaded
55b5 6d82 7f98 f81e 3fc6 9e03 c0c1 f739
7fa4 0bff 4e36 0303 9ddd 50a2 6ae2 8229
Hash
Novermber 2017
December 2017
302
Redirect
Requesting URI-M1
Requesting URI-M1 URI-M2
50
Changes in TimeMaps à different hashes
URI-M1 was
NOT available
web.archive.
org/web/2008
0828005922/h
ttp://www.ev
angelcogdayt
on.org/
web.archive.
org/web/2009
0211151609/h
ttp://www.ev
angelcogdayt
on.org/
URI-M 1
URI-M 2

51
Transient error
• Incomplete HTTP entity
http://webarchive.nationalarchives.gov.uk/20170303010736id_/https://cereals.ahdb.org.uk/media/1157842/corporate-strategy-1.jpg
Download the image on December 7, 2017
WARC/1.0
WARC-Type: response
WARC-Target-URI:
http://webarchive.nationalarchive
s.gov.uk/20170303010736id_/https:
//cereals.ahdb.org.uk/media/11578
42/corporate-strategy-1.jpg
WARC-Date: 2017-12-07T10:04:18Z
…
Content-Length: 459640
HTTP/1.0 200
Content-Type: image/jpeg
Date: Thu, 07 Dec 2017 10:04:18
GMT
…
The first
Content-length
should be bigger
than the second
one

52
The complete HTTP entity
http://webarchive.nationalarchives.gov.uk/20170303010736id_/https://cereals.ahdb.org.uk/media/1157842/corporate-strategy-1.jpg
WARC/1.0
WARC-Type: response
WARC-Target-URI:
http://webarchive.nationalarchive
s.gov.uk/20170303010736id_/https:
//cereals.ahdb.org.uk/media/11578
42/corporate-strategy-1.jpg
WARC-Date: 2017-11-16T15:34:37Z
…
HTTP/1.0 200
Content-Type: image/jpeg
Date: Thu, 16 Nov 2017 15:34:36
GMT
…
This is what it
should look like

53
Requirements for an archive-aware
hashing function
1. Generate a hash on a composite memento
2. Exclude archive-specific resources
3. Avoid resources from the live web
4. Avoid content served from cache
5. Changes in TimeMaps might affect the
computation of hashes
6. Avoid including dynamic content

54
Dissertation plan
Read Literature
repeatable hashes
PhD Defense
and select one

55
Our study indicates 28% of
mementos produce different hashes
• 17,074 archived page
• From 17 public web archives
• Downloaded 20 times
• Between November 16, 2017 and
March 27, 2018
Preliminary work

56
Archive Mementos
Mementos with
different hashes (%)
archive.org 1,600 1,027 (64%)
webarchive.loc.gov 1,600 821 (51%)
vefsafn.is 1,600 764 (48%)
arquivo.pt 1,600 305 (19%)
webcitation.org 1,600 57 (4%)
archive.is 1,600 0 (0%)
archive-it.org 1,407 489 (35%)
swap.stanford.edu 1,233 195 (16%)
nationalarchives.gov.uk 1,011 95 (9%)
europarchive.org 990 97 (10%)
webharvest.gov 733 178 (24)
digar.ee 518 81 (16%)
webarchive.proni.gov.uk 477 50 (10%)
webarchive.org.uk 362 275 (76%)
collectionscanada.gc.ca 359 13 (4%)
archive.bibalex.org 202 156 (77%)
perma-archives.org 182 147 (81%)
17,074 4,750 (28%)
Mementos with different
hashes per archive

57
Dissertation plan
Read Literature
repeatable hashes
PhD Defense
and select one

An Approach for Verifying Fixity of
Archived Web Resources
58
Use web archives to monitor web archives

Step 1: Push to multiple archives
59
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov

Step 2: Compute fixity,
publish fixity “manifest” at a well-known location
60
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
• Compute fixity on things that should not change, like JPEGs and certain original
HTTP response headers.
• This example assumes the existence of a well-known server manifest.org.
• Actual URIs can be a bit more complex using “Trusty URIs”: http://ws-
dl.blogspot.com/2017/01/2017-01-15-summary-of-trusty-uris.html

Wondering about veracity of an archived page?
Check manifest.org and recompute fixity.
61
climate.nasa.gov climate.nasa.gov
We can’t know archive.org did not alter contents on ingest (20180321),
but we can verify that it has not changed since our observation (20180322)
What if manifest.org is
down? or possibly
hacked?

Step 3: Push manifest to multiple archives
62
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
• Now the 20180322 version of the manifest of archive.org’s memento
of climate.nasa.gov is in four different archives.
• The URIs are more complex, but the bottom line is an attacker would
have to hack a majority of 5 domains (manifest.org + 4 archives)

Wondering about veracity of an archived
page? Check all copies of manifest.org and
take a majority vote
63
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
climate.nasa.gov
• Caveat 1: If I can hack nasa.gov page at archive.org, I can probably
hack the fixity info there too, so we really have 4 copies not 5.
• Caveat 2: archive.org and archive-it.org are not independent,
• so we really have 3 copies not 5.

64
Dissertation plan
Read Literature
repeatable hashes
PhD Defense
and select one

Probability model of rendering
the same archived pages
65
- Download a number of mementos multiple
times at different points in time
- Compute a hash on each memento after
each download
- Try to find an answer to the question: what
is the probability of getting the same hash
value?

66
Dissertation plan
Read Literature
repeatable hashes
PhD Defense
and select one

67
- Open Annotation Data Model (OA)
- Open Archives Initiative: Object Reuse and
Exchange (OAI-ORE)
- Linked Data Platform (LDP)
- Open Annotation Protocol
- WAT/WET
- BagIt
Study different existing data models for
serializing fixity information and select one

68
Dissertation plan
Read Literature
repeatable hashes
PhD Defense
and select one

69
Dissertation plan
Read Literature
repeatable hashes
PhD Defense
and select one

When can fixity information be
generated?
70
1. By the archive on ingest
2. At any time after the archived
content is made available
time
• A web page is captured by the archive at t0
1
t0 t7
1
2
• By , we can trust the archived page since t0
• By , we can trust the archived page since t7. but we
cannot detect changes before t7
1
2
2

Is our proposed
framework scalable?
71
• Time required to generate fixity
information per memento per archive
• Time required to verify fixity of
mementos
• The size of fixity information ”manifest”
• Scalable? Or just on important
mementos (e.g., the archived NASA
page)

Only independent copies of manifest
should be counted
72
• Copies in Internet Archives and Archive-it
are not independent
• Copies of copies are not independent

73
Dissertation plan
Read Literature
repeatable hashes
PhD Defense
and select one
[ Current State ]
Preliminarywork
July 2018
November 2018
August 2018
February 2019
May 2019

75
Creating trusted archives
Trustworthy Repositories Audit & Certification: Criteria and Checklist, Version
1.0, The Center for Research Libraries and OCLC Online Computer Library
Center, Inc. (2007). ( Sections B2.9 and B4.4 )
• Web archives must create preservation
metadata that can be used to verify fixity
• Preserved content should be stored
separately from fixity information
( hard for someone to alter both )
Related Work

76
Threats
• D. S. H. Rosenthal, T. Lipkis, T. S. Robertson, and S. Morabito. Transparent Format Migration of Preserved Web Content. D-Lib Magazine, 11(1), 2005.
• A. Lerner, T. Kohno, and F. Roesner. Rewriting history: Changing the archived web from the present. In Proceedings of the 16th ACM conference on
Computer and Communications Security (CCS), pages 1741–1755, 2017.
• J. Cushman and I. Kreymer. Thinking like a hacker: Security Considerations for High-Fidelity Web Archives.
http://labs.rhizome.org/presentations/security.html, May 2017.
• Rosenthal et al. described several threats against digital preservation
systems:
• Lerner et al. discovered four vulnerabilities in the Internet Archive’s
Wayback Machine (i.e., Archive-Escapes, Same-Origin Escapes, Archive-
Escapes + Same-Origin Escapes, and Anachronism- Injection) that
attackers can leverage to modify a user’s view in a browser
• Cushman and Kreymer created a shared repository in May 2017 to
demonstrate potential threats in web archives (e.g., controlling a user’s
account due to Cross-Site Request Forgery (CSRF) or archived web
resources reaching out to the live web)
- Media failure, software failure, failure of network
services, natural disaster, internal attack, organizational
failure, hardware failure, …
Related Work

77
Hashes in URIs
• T. Kuhn and M. Dumontier. Trusty uris: Verifiable, immutable, and permanent digital artifacts for linked data. In European Semantic Web Conference,
pages 395–410. Springer, 2014.
• T. Kuhn and M. Dumontier. Making digital artifacts on the web verifiable and reliable. IEEE Transactions on Knowledge and Data Engineering,
27(9):2390–2400, 2015.
• Multihash. https://github.com/multiformats/multihash.
• Kuhn et al. define a Trusty URI as a URI that contains a cryptographic hash
value of the content it identifies. Trusty URIs can be generated on only two
types of content RDF graphs and byte-level content (i.e., no modules introduced
for HTML documents).
Related Work
• Juan Benet introduced Multihash to mainly create self identifying hashes for IPFS
content

78
Trusted timestamps in
blockchain-based networks
• https://originstamp.org
• https://chainpoint.org/
• https://opentimestamps.org/
• A. Wright and P. De Filippi. Decentralized blockchain technology and the rise of lex cryp- tographia. In SSRN Electronic Journal, 2015.
• OpenTimestamps, OriginStamp, and Chainpoint generate
trusted timestamps using Bitcoin blockchain.
Related Work
File
• The common steps for timestamping:
1. Receiving a file, a hash, or plain text from a user
2. Generating a hash value of received content
3. Converting the hash to a Bitcoin address
4. Issuing a Bitcoin transaction using the Bitcoin address
• The timestamp associated with the transaction is used as
a trusted timestamp

79
Distributed copies of archived
resources
• P. Maniatis, M. Roussopoulos, T. J. Giuli, D. S. Rosenthal, and M. Baker. The lockss peer-to-peer digital preservation system. ACM Transactions on
Computer Systems (TOCS), 23(1):2–50, 2005.
• B. Kahle. Help Us Keep the Archive Free, Accessible, and Reader Private. https: //blog.archive.org/2016/11/29/help-us-keep-the-archive-free-
accessible-and- private/, November 2016.
Related Work
- Built so that each participating library has its own copy of
scholarly papers
- LOCKSS regularly compares these copies and detects
corrupted ones based on voting on the cryptographic
hash of the content
- Replacing any corrupted copy with the right content
• The Internet Archive are planning to build a new archive
in Canada to duplicate all current archived collections.
• Lots of Copies Keep Stuff Safe (LOCKSS)

December 2017
March 2018
302
Redirect
Requesting URI-M1
Requesting URI-M1 URI-M2
80
URI-M1 was
NOT available
URI-M1 = web.archive.org/web/20110116134258id/http://1.gravatar.com/avatar/117a6cc4203b951f11fc
43f946106657?s=33&d=http%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D33&r=G
URI-M2 = web.archive.org/web/20120121090532id/http://1.gravatar.com/avatar/117a6cc4203b951f11fc
43f946106657?s=33&d=http%3A%2F%2F1.gravatar.com%2Favatar%2Fad516503a11cd5ca435acc9bb6523536%3Fs%3D33&r=G
Changes in TimeMaps à different image à different hashes
• You can't see the difference in the URI-M of the main HTML file, but you
can see the difference in the embedded images
https://web.archive.org/web/20110114074814/http://www.copyblogger.com:80/popular-blogger/
https://web.archive.org/web/20110114074814/http://www.copyblogger.com:80/popular-blogger/

December 12, 2017
302
Redirect
Requesting URI-M1
Requesting URI-M1 URI-M2December 25, 2017
URI-M1 = perma-archives.org/warc/20170101182814id_/
http://umich.edu/includes/image/type/gallery/id/113/name/Resea
rchDIL19Aug14_DM%28136%29.jpg/width/152/height/152/mode/minfit/
URI-M2 = perma-archives.org/warc/20170619145458id_/
http://umich.edu/includes/image/type/gallery/id/113/name/Resea
rchDIL19Aug14_DM%28136%29.jpg/width/152/height/152/mode/minfit/
URI-M1 was
NOT available
Different image
Changes in TimeMaps à different image that looks the same à different hashes
• You can't see the difference in the URI-M of the main HTML file nor the
difference in the embedded images
http://perma-archives.org/warc/20170101182813id_/http://umich.edu/
http://perma-archives.org/warc/20170101182813id_/http://umich.edu/

82
http://wayback.vefsafn.is/wayback/20130313210447id_/http://vkontakte.ru/
Requesting the raw version, received ”200 OK” with a
rewritten version that indicates “302 Redirect”
curl -I http://wayback.vefsafn.is/wayback/20130313210447id_/http://vkontakte.ru/
HTTP/1.1 200 OK
Date: Tue, 05 Jun 2018 17:34:19 GMT
Server: Apache/2.4.6 (Red Hat Enterprise Linux)
Content-Security-Policy: default-src 'self' style-src 'self' 'unsafe-inline'
Memento-Datetime: Wed, 13 Mar 2013 21:04:47 GMT
…
http://wayback.vefsafn.is/wayback/20130313210447id_/http://vkontakte.ru/

83
http://webharvest.gov/congress110th/20081124195939id_/http://www.usda.gov/
Requesting the raw version of webharvest.gov/congress110th/2008
1124195939id_/http://www.usda.gov/, it redirects to the live web

84
http://webharvest.gov/congress110th/20081124195939id_/http://www.usda.gov/
Requesting the raw version of webharvest.gov/congress110th/2008
1124195939id_/http://www.usda.gov/, it redirects to the live web
curl -iL --silent webharvest.gov/congress110th/20081124195939id_/http://www.usda.gov/ |
egrep -i "(HTTP/1.1|^location:)"
HTTP/1.1 301 Moved Permanently
Location: https://webharvest.gov/congress110th/20081124195939id_/http://www.usda.gov/
Location:
https://www.webharvest.gov/congress110th/20081124195939id_/http://www.usda.gov/
HTTP/1.1 302 Found
Location: http://www.usda.gov/wps/portal/usdahome
Location: https://www.usda.gov/wps/portal/usdahome
location: https://www.usda.gov/

Requesting the raw version, a third party
service (Cloudflare) injects HTML code
curl -s http://perma-archives.org/warc/20171026200017id_/https://www.usa.gov/federal-
agencies/a
| egrep -i "(cdn-cgi|^Date:)"
Date: Tue, 15 May 2018 21:00:45 GMT
<a href="/cdn-cgi/l/email-
protection#28175b5d4a424d4b5c15690854086905720861464c4d5008474e087d067b06086f475e4d5a464
54d465c086c4d58495a5c454d465c5b0849464c08694f4d464b414d5b0e494558134a474c5115405c5c585b1
207075f5f5f065d5b49064f475e074e4d4c4d5a494405494f4d464b414d5b0749” …
curl -s http://perma-archives.org/warc/20171026200017id_/https://www.usa.gov/federal-
agencies/a
Date: Tue, 15 May 2018 21:00:50 GMT
protection#68571b1d0a020d0b1c55294814482945324821060c0d1048070e483d463b46482f071e0d1a060
50d061c482c0d18091a1c050d061c1b4809060c48290f0d060b010d1b4e090518530a070c1155001c1c181b5
247471f1f1f461d1b09460f071e470e0d0c0d1a090445090f0d060b010d1b4709” …
curl -silent http://perma-
archives.org/warc/20171026200017id_/https://www.usa.gov/federal-agencies/a
Date: Tue, 15 May 2018 21:00:51 GMT
protection#b986caccdbd3dcdacd84f899c599f894e399f0d7dddcc199d6df99ec97ea9799fed6cfdccbd7d
4dcd7cd99fddcc9d8cbcdd4dcd7cdca99d8d7dd99f8dedcd7dad0dcca9fd8d4c982dbd6ddc084d1cdcdc9ca8
39696cecece97cccad897ded6cf96dfdcdddccbd8d594d8dedcd7dad0dcca96d8” …

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