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Toshiba, Hitachi, IBM, Plextor drives. Software. CD Player

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Toshiba, Hitachi, IBM, Plextor drives. Software. CD Player, MusicMatch, Nero, CloneCD (Windows) ... Toshiba drive broken until reboot. Most tests failed (62/75) ... – PowerPoint PPT presentation

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Title: Toshiba, Hitachi, IBM, Plextor drives. Software. CD Player


1
Evaluating New Copy-Prevention Techniques for
Audio CDs
  • J. Alex Halderman
  • Princeton University Department of Computer
    Science

2
Copy-Resistant CDs - Overview
  • Modified discs
  • Play on CD players, hard to read on PCs
  • Response to consumer piracy
  • Deliberate errors
  • Audio data / metadata
  • Variations from several vendors
  • Few discs today many coming soon
  • BMG, EMI, etc.

3
Notable Drawbacks
  • Primarily affects legitimate CD owners
  • Confusing hardware/software errors
  • Violates standards, bad engineering practice
  • Effectiveness for reducing unlawful copying
    hasnt been demonstrated

4
Interesting Questions for C.S.
  • Are they effective?
  • How do they work?
  • Can they be defeated?
  • Who wants to know?
  • Record companies, musicians, policy makers,
    software authors, music buyers, researchers

5
Tested Three Discs
Music City, 2001 MediaCloQ (SunnComm)
Columbia/Sony, 2002 key2audio (Sony)
Universal, 2001 Cactus Data Shield (Midbar)
6
Not Addressed
  • Why would anyone want to copy these discs?

7
Question 1
  • Are these techniques effective?

8
Test Configurations
  • Covered range of deployed systems
  • Operating System
  • Windows, Linux
  • Hardware
  • Toshiba, Hitachi, IBM, Plextor drives
  • Software
  • CD Player, MusicMatch, Nero, CloneCD (Windows)
  • CDP, CD Paranoia, CDR-DAO (Linux)

9
Test Results
  • Variety of errors
  • disc not detected invalid data crashes
  • Toshiba drive broken until reboot
  • Most tests failed (62/75)
  • Some successful
  • CD Paranoia, CloneCD (Plextor hardware)

10
Implications
  • Seemingly effective today against deployed
    hardware, typical applications
  • Some configurations already can play
  • Greater compatibility is possible
  • Different modes of failure
  • Schemes use slightly different measures (more
    detail later)

11
Question 2
  • How do these techniques work?

12
How Do These Schemes Work?
  • Exploit bugs, lack of robustness in hardware and
    software
  • Unexpected deviations from standards
  • Two levels of failure
  • Hardware Drives reject the discs (firmware)
  • Software Apps fail even on working drives

13
Normal CD Structure
  • Discs divided into tracks
  • Tracks listed in table of contents (TOC)
  • May be grouped into sessions
  • Drives read TOC from each session, return list of
    tracks
  • CD players only see session 1
  • Observed two main categories of deviations

Session 1
CD players
TOC
Track 1
Track 2

Session 2
TOC
CD drives
Track
Track


14
Fake TOC Entries - Software
  • Invalid TOC entries in session 2
  • Bad track locations
  • Audio marked as data
  • Drive returns invalid listing, fools software
  • CD players only read first session, unaffected

Session 1
CD players
Real TOC
Track 1
Track 2

Session 2
Fake TOC
Data Track
CD drives
15
Fake Session Pointers - Hardware
  • Session 2 contains pointer to fake session near
    outer edge of disk
  • Incomplete TOC, no lead out
  • Fatal errors in some hardware (e.g. Toshiba)
  • Possible variations
  • No pointers to earlier sessions
  • Physical incompatibilities making earlier session
    hard to reach

Session 1
CD players
Real TOC
Track 1
Track 2

Session 2
Fake TOC
CD drives
Fake Session
16
Question 3
  • Can these techniques be defeated?

17
Felt-Tipped Pen Hack
(Appeared on Chip.de early May 2002)
  • Hides last TOC containing invalid track/ session
    entries
  • Drives see only first TOC, so disc can be read
    normally
  • Outlaw felt-tipped pens!

Last TOC area obscured by marker
18
How to Adapt Hardware
  • Direct fix compatibility mode
  • Emulates CD player
  • Not even necessary
  • Indirect fix greater robustness
  • Fix bugs (firmware)
  • Better error reporting
  • More robust failure modes
  • Error interpolation

19
How to Adapt Software
  • Bug fixes, greater robustness
  • Ignore obvious errors (warnings, not failure)
  • Scan for track starts by binary search
  • Interpolate over missing samples
  • Changes ensure maximum compatibility with all
    faulty discs, not just copy-protected

20
Change is Underway
  • Software
  • Audiograbber, CloneCD, and EAC have modes for
    handling protected discs
  • Hardware
  • Plextor, others work today

21
Can They Be Defeated?
  • Yes!
  • Offer minimal protection today, but will be
    easily adapted to (already happening)
  • Rate of adaptation proportional to rate of
    deployment
  • Schemes ineffective against copying in the near
    future (by the time they are widespread)

22
Conclusions
  • Partial incompatibility with spec. wont work
  • Software too easy to adapt and distribute
  • Takes advantage of HW/SW flaws
  • Prohibiting circumvention would be to mandate
    bugs!
  • Relies on stopping reading in most cases but
    can be copied online if just some can read
  • True for tested discs
  • Circumvention easy, cant be stopped everywhere

23
Conclusions
  • In present form, these schemes are worse than
    useless
  • Bad hacks
  • Wont prevent illegal copying
  • Inconveniences legitimate music owners
  • May make people less willing to buy CDs
  • Further alienates public from music industry
  • Industry must find an alternative
  • DRM? New business model?
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