1
INTRODUCTION TO TIME TRAVEL
-OR-
HOW TO SEND YOUR FILES TO THE FUTURE
2
TIME TRAVEL: A MODIFIED DEFINITION
COMMUNICATION ACROSS TIME AND SPACE
3
A BRIEF HISTORY OF TIME TRAVEL
RECENT ATTEMPTS AT TIME TRAVEL
5
INFORMATION PRESERVATION
REQUIRES DIGITAL PRESERVATION
The Future!
A long time ago…
Today
Today
Analog
Digital
6
WHAT DOES ‘DIGITAL’ ACTUALLY MEAN?
(FOR STORAGE)
7
MAGNETIC MEDIA: HARD DRIVES
Peaks = 1sTroughs = 0s
8
SOLID STATE MEDIA: SD CARDS
9
OPTICAL MEDIA: CDS
10
A QUESTION OF REPRESENTATION
“I am the wisest man alive, for I
know one thing, and that is that I know nothing.”
-Plato
00100010010010010010000001100001011011010010000001110100011010000110010100100000011101110110100101110011011001010111001101110100001000000110110101100001011011100010000001100001011011000110100101110110011001010010110000100000011001100110111101110010001000000100100100100000011010110110111001101111011101110010000001101111011011100110010100100000011101000110100001101001011011100110011100101100001000000110000101101110011001000010000001110100011010000110000101110100001000000110100101110011001000000111010001101000011000010111010000100000010010010010000001101011011011100110111101110111001000000110111001101111011101000110100001101001011011100110011100101110001000100000110100001010001011010101000001101100011000010111010001101111
= =
11
"I am the wisest man"alive, fob I know one
thing, and that is that I onow nothing."
-Plato
“I am the wisest man alive, for I know one thing, and
that is that I know nothing.”
-Plato
BIT ROT: THE DEGRADATION OF BITS OVER TIME
3 Bits CorruptedOriginal Text
12
BITLOSS
& DIGITALPHOTOS
Images from Melanie Willhide’s “to Adrian Rodreguez with love”http://www.vonlintel.com/Melanie-Willhide.html
13
ALMOST LOST
NASA images from first Lunar Orbiter 1966
BBC Domesday Project 1986
14
DOMESDAY PROJECT
15
DIGITAL PRESERVATION STRATEGIES
1. Format Choice
2. Documentation
3. Migration
4. Emulation
5. Hashing/checksums
6. File Identification
16
1. FORMAT CHOICE
Hardware
Software
17
NDIIPP
http://www.digitalpreservation.gov/formats/index.shtml
18
THE LIBRARY OF CONGRESS:DIGITAL PRESERVATION
http://www.digitalpreservation.gov/
19
2. DOCUMENTATION & METADATA
• File Name• File Size• Number of Words• Total Editing Time• Creation Date• Last Modified• Last Printed• User Name
• File TypeWord Doc
• Software VersionMS Word 2010
20
3. MIGRATION
• The transfer of a bit stream (the 1s and 0s) from one medium to another.
21
FINDING THE HARDWARE
22
MIGRATION
Similar to photocopying –including the imperfections.
Data can be lost or corrupted in the transfer.
23
WRITE BLOCKERS
• Prevents inadvertently overwriting digital information.
• Allows ‘read’ commands to pass, blocks ‘write’ commands.
24
4. EMULATIONCreates an environment that ‘tricks’ the software into functioning as if it was in its original computing environment.
Similar to impersonation.
25
EMULATION & THE GAMING COMMUNITY
"The Old Version Flickers More": Digital Preservation from the User's Perspective
http://archivists.metapress.com/content/1765364485n41800/
26
BROWSER BASED EMULATION
https://archive.org/details/historicalsoftware
27
5. HASHING/CHECKSUMS
How they work:An algorithms ‘reads’ a digital object and, based upon the 1s and 0s that make up that object, produces a unique alpha-numeric string of characters that represent it.
What that means:Checksums are very effective tools in determining if a digital object has been corrupted (assuming you have the original checksum to compare it to).
28
HASHING
461D5E8093B94401EAF12E442CEAB908
FD7D5993062D270F482E00BDE64D35FE
Original File
Corrupted File
MD5 Hash
29
HASHING
http://download.cnet.com/MD5-SHA-Checksum-Utility/3000-2092_4-10911445.html
30
HASHING IN TWO STEPS
31
IDENTIFYING MYSTERY FILES
.hqx? .mkv? .ape?
You have to identify what a file is in order to figure out what software can render it. But how?
32
6. FILE IDENTIFICATION
Step 1: Google the file extension
33
IDENTIFYING MYSTERY FILES
34
IDENTIFYING MYSTERY FILES
Step 1: Google the file extension
Step 2: If step 1 fails, use DROID
35
Digital Record Object Identification
http://www.nationalarchives.gov.uk/information-management/our-services/dc-file-profiling-tool.htm
36
IDENTIFYING MYSTERY FILES
Step 1: Google the file extension
Step 2: If step 1 fails, use DROID
Step 3: If step 2 fails, open it in a hex editor
37
HXD HEX EDITOR
http://download.cnet.com/HxD-Hex-Editor/3000-2352_4-10891068.html
38
HEX EDITOR VIEW
39
FILE SIGNATURES/MAGIC NUMBERS
• Every file type has a digital ‘finger print’ near the beginning of its code, sometimes called a ‘signature’ or ‘magic number’.
• In a hex editor, you can read the hexadecimal notation of the file and identify its magic number, then look up that number to identify the file type.
40
WIKIPEDIA’S FILE SIGNATURE LIST
http://en.wikipedia.org/wiki/List_of_file_signatures
41
IF YOU HAVE QUESTIONS ABOUT DIGITAL PRESERVATION
THE LIBRARY IS HERE TO HELP
42
Shea SwaugerData Management Librarian
Morgan Library, [email protected]
Questions?
This presentation is available at http://www.slideshare.net/SheaSwauger