DVDs and TPMs: how often is CSS used?

On June 2, the Canadian government tabled Bill C-32, its third attempt to implement anti-circumvention laws and other changes to the Copyright Act of Canada. The proposed changes would significantly impact the way Canadians are allowed to interact with copyrighted works stored in digital form, such as movies stored on DVDs. Not much information is available on the DVD situation in particular so there is significant uncertainty as to whether C-32 prohibits DVD backups (as an example):

• xentac: “with BillC32 can I buy DVDs and rip them…?”; Tony Clement: “So long as no TPM”
• Drew Wilson: “If you have a home movie recorded on a DVD and you back that movie up…, you’ve broken the anti-circumvention law.”; anonymous commenter: “This isn’t correct. Home movies you burn onto a DVD-R/RW are not CSS encrypted, only commercial DVDs are.”

By “CSS”, the anonymous commenter means Content Scramble System, an optional method of obfuscating the data on DVDs (what some would call DRM). CSS seems to be a “technological protection measure” (TPM) according to C-32 (“any effective technology, device or component that, in the ordinary course of its operation, controls access to a work…”) so I will proceed under this assumption. Hopefully someone closer to the bill can comment on the validity of this assumption.

To provide some clarity to the issue of which DVDs are encumbered by CSS (and thus could not be legally backed up or used for fair dealing under C-32), I analyzed 66 DVDs in my household’s DVD collection to determine if they used CSS. Here are the results:

DVDs encumbered by CSS

(illegal to backup or use for fair dealing under C-32)

Big Six and mini-majors

“Independent” studios

DVDs not encumbered by CSS

(legal to backup or use for fair dealing under C-32)

“Independent” studios

Summary

• Of the 66 DVDs tested, 57 (86.4%) were encumbered with CSS and 9 (13.6%) were CSS-free
• All of the 45 DVDs from the Big Six and mini-major film studios were encumbered with CSS (they are all illegal to backup or use for fair dealing under C-32)
• Of the 21 DVDs from “independent” studios (those that don’t appear to be directly linked to a Big Six or mini-major studio), 12 (57.1%) were encumbered with CSS and 9 (42.9%) were CSS-free

Conclusion

The use of CSS in DVDs is very prevalent, especially among the Big Six and mini-major film studios, which made up over 98.23% of the market in 2009 (adding the top 18 figures from Market Share for Each Distributor in 2009). Given this market share figure, the sample of DVDs I used in testing was disproportionately skewed toward toward “independent” studios, and thus had fewer CSS-encumbered DVDs than the average household’s DVD collection would have. I suspect that 98% of the DVDs in an average household’s collection would be encumbered by CSS and therefore would be illegal to backup or use for fair dealing under Bill C-32.

I agree with the anonymous poster who said that home movies are not encumbered by CSS and so they can be backed up legally under C-32. Adding CSS to a DVD is not done by default and is difficult to do, requiring a license from the DVD CCA.

Methodology

To determine whether a DVD used CSS or not, I wrote the following C program, which I linked with libdvdcss 1.2.10 and ran after inserting each DVD:

#include <dvdcss.h>
#include <stdio.h>

int main(void)
{
        dvdcss_t dvd;

        dvd = dvdcss_open("/dev/cdrom");
        if (NULL == dvd) {
                printf("cannot open DVDn");
                return 1;
        }

        printf("scrambled (1=yes, 0=no): %dn", dvdcss_is_scrambled(dvd));
        dvdcss_close(dvd);

        return 0;
}

I obtained region code information from the debug output of libdvdcss that appeared when I ran the above program.

libdvdcss and Bill C-32

Ironically, downloading libdvdcss would likely become illegal in Canada under C-32 because it states “No person shall…import…any technology…if…the technology, device or component is designed or produced primarily for the purposes of circumventing a technological protection measure” (Section 47 of Bill C-32, proposed Section 41.1(1)(c)(i) of the Copyright Act). This is because the primary purpose of libdvdcss is to circumvent CSS (which I’m assuming is a TPM), even though it can be used for other purposes, such as checking whether a DVD uses CSS or not. I would appreciate clarification on this point from those close to the bill.

It’s important to note that the primary use case for libdvdcss is playing DVDs using free software, such as VLC, not to make illegitimate copies of DVDs. Because the DVD CCA will not provide a license for free software players (because they cannot comply with Section 6.2.4 of the CSS Procedural Specifications, which states “All implementations…shall include features clearly designed to effectively frustrate…attempts to discover decrypted confidential CSS Keys”), people who wish to play CSS-encumbered DVDs with free software must necessarily circumvent the CSS.

A major reason for publishing the above list of DVDs which use CSS is that I couldn’t find an existing online source that provided similar information. Perhaps it is because of the effective ban on libdvdcss in the US due to the DMCA that such information is not more widely available. It is important for those considering new laws to consider these and other unintended consequences of anti-circumvention clauses. The EFF has compiled a detailed list of such unintended consequences of the DMCA: Unintended Consequences: Twelve Years under the DMCA. Perhaps we can learn from the US’ mistakes.