Feeds

Tiny C code bests seven-line DVD decoder

Smaller, way faster

  • alert
  • submit to reddit

The smart choice: opportunity from uncertainty

Coder Charles M Hannum has created the smallest program capable of decoding a Content Scrambling System (CSS) DVD file, beating last week's seven-line Perl shell script 442 bytes to 472 (excluding newline bytes).

Hannum's C program, called efdtt, is no slouch, either. The programmer claims it can "descramble in excess of 21.5MBps" - faster than the DVD spec. allows for. The speed comes "without even particularly trying to optimise the I/O. This makes it pretty insignificant compared to the rest of the decoding process" = in other words, it's quick enough not to impede the MPEG 2 decode operation which turns the data into a moving image.

Apparently, the latter may be a problem with qrpff, the Perl CSS descrambler written by Keith Winstein and Marc Horowitz, and posted on Carnegie Mellon University professor David Touretzky's DSS Descrambler Gallery Web site. Winstein and Horowitz' code was capable of supporting realtime decode and playback, but we're told the output was occasionally jerky.

Hannum's code should allow smooth playback.

Both scripts do what the controversial DVD-on-Linux utility DeCSS does - and demonstrate how simple CSS, the DVD standard's copyright protection mechanism, is to decode. The Motion Picture Association of America has been pretty successful in repressing the distribution of DeCSS, viewing it as a threat to movie industry copyright - and movie industry profits.

"So what's the MPAA gonna do now?" Touretzky asks. "This code is small enough to put on a cocktail napkin. Commit to memory. Knit into a scarf. Whatever. It cannot be suppressed." ®

Related Link

Dave Touretzky's Gallery of CSS Descramblers
Charles M Hannum's efdtt.c

Related Story

Seven-line program beats DVD crypto

Securing Web Applications Made Simple and Scalable

More from The Register

next story
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
Put down that Oracle database patch: It could cost $23,000 per CPU
On-by-default INMEMORY tech a boon for developers ... as long as they can afford it
Google shows off new Chrome OS look
Athena springs full-grown from Chromium project's head
Apple: We'll unleash OS X Yosemite beta on the MASSES on 24 July
Starting today, regular fanbois will be guinea pigs, it tells Reg
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.