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Politech is the oldest Internet resource devoted to politics and technology. Launched in 1994 by Declan McCullagh, the mailing list has chronicled the growing intersection of culture, technology, politics, and law. Since 2000, so has the Politech web site.
Thanks, all, for the replies. The breadth of legal and technical knowledge among Politech readers is always impressive. Previous message: "Rep. Boucher sends nastygram to music firms re: copy-protected CDs" http://www.politechbot.com/p-02997.html -Declan ********* Date: Mon, 07 Jan 2002 12:26:21 -0500 To: declan@well.com From: Jon Zittrain <zittrain@cyber.law.harvard.edu> Subject: Re: FC: Rep. Boucher sends nastygram to music firms re: copy-protected CDs In-Reply-To: <5.1.0.14.0.20020107103428.029e6990@mail.well.com> I wholeheartedly agree with the spirit of the idea that new technical copy protection schemes could upset the balance, such as it is, struck by copyright law. Copyright law's protectable property rights are by no means absolute, as others have pointed out with such examples as limited temporal term, fair use exceptions, and the first sale doctrine, which says that after I buy a book the seller/publisher has no business telling me that I can't lend it or resell it to someone. But the Audio Home Recording Act was drafted by the publishers -- I don't see how anyone reading it could readily find it to say that it prohibits private, technical copy protection schemes that, to be sure, trample copyright's balance. Similarly, the royalties owed publishers on things like DAT unit and blank tape sales (an extraordinary law!), don't seem to be conditioned on the devices' incorporating an ability to make noncommercial copies.. Congress would do well to go ahead and pass such a law regarding mass publishers' "copyduty" -- and I'm hoping today that the Supreme Court will announce that it's taking the case of Eldred v. Ashcroft, which challenges the Sonny Bono Copyright Term Extension Act of '98 as an unconstitutional retroactive extension of "limited terms." But I don't think a "copyduty" law is already on the books. Perhaps the next step would be for Rep. Boucher to get a hearing going on what a copyduty law might look like. The publishers would come out of the woodwork to fight it. Here's the provision in question: <http://caselaw.lp.findlaw.com/casecode/uscodes/17/chapters/10/subchapters/d/sections/section_1008.html> -- it just says that the record companies can't sue over people making certain kinds of copies, not that they have to allow those copies to be made. Title 17, Section 1008. Prohibition on certain infringement actions No action may be brought under this title alleging infringement of copyright based on the manufacture, importation, or distribution of a digital audio recording device, a digital audio recording medium, an analog recording device, or an analog recording medium, or based on the noncommercial use by a consumer of such a device or medium for making digital musical recordings or analog musical recordings. ...JZ Jon Zittrain Harvard Law School Jack N. & Lillian R. Berkman Assistant Professor of Entrepreneurial Legal Studies Faculty Co-Director, Berkman Center for Internet & Society <http://cyber.law.harvard.edu> ********* Date: Mon, 7 Jan 2002 12:19:05 -0500 To: declan@well.com From: Marc Rotenberg <rotenberg@epic.org> Subject: Re: FC: Rep. Boucher sends nastygram to music firms re: copy-protected CDs Cc: hoofnagle@epic.org There is a new page today up at the EPIC site (epic.org) on Digital Rights Management. It's very extensive. Marc. ********* Subject: Re: FC: Rep. Boucher sends nastygram to music firms re: copy-protected CDs From: Christopher Cramer <chris.cramer@duke.edu> To: declan@well.com Date: 07 Jan 2002 13:05:45 -0500 Declan, There are a handful of different/competing copy protection mechanisms. They all involve writing CDs in ways they weren't meant to be written and most take advantage of the fact that CD players are dumb while CDROM drives are more intelligent. For example, one mechanism writes bad checksums for some of the good blocks of audio data. Most CD players will go ahead and play right through it. A CDROM drive will see the bad checksum and return no data to the program. This will result in static on a ripped or copied CD. Other mechanisms involve writing bad table of contents information. There is a discription of one of the copy protection mechanisms (SunnComm's Digital Content Cloaking Technology) at the URL: http://uk.eurorights.org/issues/cd/charley_pride.shtml Hope this helps. -Chris -- Christopher E. Cramer, Ph.D. Information Technology Security Officer Duke University, Office of Information Technology 253A North Building, Box 90132, Durham, NC 27708-0291 PH: 919-660-7003 FAX: 919-660-7076 email: chris.cramer@duke.edu ********* From: "Aaron Miller" <amiller@digitalgroup.org> To: <declan@well.com>, <politech@politechbot.com> References: <5.1.0.14.0.20020107103428.029e6990@mail.well.com> Subject: Re: Rep. Boucher sends nastygram to music firms re: copy-protected CDs Date: Mon, 7 Jan 2002 12:32:36 -0500 Hi Declan - > [Does anyone have a pointer to a detailed technical description of how the > copy protection mechanism works? --Declan] http://www.cdrfaq.org/ Section 2-4... is an excellent place to start - I will continue to scour my resources and see if I can find a more techincal explanation of how the technology actually works. Be well - Aaron Miller ********* Date: Mon, 7 Jan 2002 14:02:26 -0500 (EST) From: "J.D. Abolins" <jda-ir@pluto.njcc.com> To: Declan McCullagh <declan@well.com> Subject: Re: FC: Rep. Boucher sends nastygram to music firms re: copy-protected CDs FWIW: Some URLs I found in a quick check for audio CD copy protection techniques (unevaluated): MacroVision's Audio Protection Info Page http://www.macrovision.com/solutions/newtech/safeaudio.php3 Article about the MacroVision method may have already been cracked (mentions a Dutch hacker site; no URL given) http://www.audiorevolution.com/news/0701/24.safeaudio.shtml Quick Overview of some types of CD copy protection from a UK CD tech site http://www.disctronics.co.uk/technology/cdaudio/cdaud_copyprot.htm MidBar Tech (mfg of one copy protection scheme; technology link provides brief overview) http://www.midbartech.com/ IEEE article on why Copy Protection is Doomed. (I don't have member access) http://www.computer.org/computer/co2001/rx048abs.htm CD-ROM Guide Site (general info clearinghouse) http://www.cdrom-guide.com/ Article about the trouble brewing over CD copy protection (seems to be full of useful pointers to other sites) http://www.computertracker.com/2001/7-Aug/page30.html CD Burner 2002 Software (claims to work past various copy protection schemes) http://www.cybercitysoftware.com/cdbur20prof.html J.D. Abolins Meyda Online -- Infosec & Privacy Studies New Website: http://www.MeydaOnline.com ********* Date: Mon, 7 Jan 2002 17:14:57 +0000 (GMT) From: Martin Keegan <mk270@cam.ac.uk> To: Declan McCullagh <declan@well.com> cc: jim@uazu.net Subject: Re: FC: Rep. Boucher sends nastygram to music firms re: copy-protected CDs On Mon, 7 Jan 2002, Declan McCullagh wrote: > [Does anyone have a pointer to a detailed technical description of how the > copy protection mechanism works? --Declan] Try the link "Dan Ackroyd's in-depth investigation of the Charlie Pride CD's copy-protection" and some of the others on this page: http://uk.eurorights.org/issues/cd/docs/ Mk ********* From: "D McOwen" <dmcowen@bellsouth.net> To: <declan@well.com> Subject: RE: Rep. Boucher sends nastygram to music firms re: copy-protected CDs Date: Mon, 7 Jan 2002 12:31:38 -0500 Declan, I will look for the white papers for you. In the mean time the main difference between consumer music only CD players and players in computers is that the computer players have error correction software built in while music only players do not. So the RIAA is obviously using that built in normally good feature and turning it into a bad feature by purposly burning the discs in a way that the standard error correction software would see the disc as so bad it cannot be played. To get just a little more technical without the white paper in hand, for example the music only CD player simply has a time out, only after a certain standardized long period that it cannot read bits from the disc would it actually error out. A music only CD player would actually display ERROR on the display at that point and no longer play any tracks or music until you open the CD door, re-seat the disc and let the player read all the track info, basically starting over manually. A computer player would attempt to restart on it's own. David McOwen ********* Subject: RE: Rep. Boucher sends nastygram to music firms re: copy-protected CDs Date: Mon, 7 Jan 2002 09:38:13 -0800 From: "Scott Neugroschl" <sneugroschl@troikanetworks.com> To: <declan@well.com> > -----Original Message----- > From: Declan McCullagh [mailto:declan@well.com] > Sent: Monday, 07 January, 2002 7:53 AM > To: politech@politechbot.com > Subject: FC: Rep. Boucher sends nastygram to music firms re: > copy-protected CDs > > > [Does anyone have a pointer to a detailed technical > description of how the > copy protection mechanism works? --Declan] Declan, I believe that the CD in question (Universal's soundtrack for "The Fast and the Furious") used Cactus Data Shield. Check out http://www.midbartech.com. There have also been many discussions of this over on slashdot (http://slashdot.org). Scott -- My opinions are my own and do not purport to reflect those of my employer ********* From: Jason Thomas <jthomas@CSE.org> To: "'declan@well.com'" <declan@well.com> Subject: RE: Rep. Boucher sends nastygram to music firms re: copy-protected CDs Date: Mon, 7 Jan 2002 12:39:05 -0500 Declan, Usually I am very skeptical of fair use claims from public domain advocates in that they attempt to take a defense against infringement and turn it into a positive right. However, in this instance I believe Rep. Boucher is correct to highlight the way copy protection infringes on the fair use rights implicit to the '92 AHRA. What seemed, at passage, to be a way to collect royalties for simply acknowledging reality has turned into a legal obstacle. It is a shame that this perfectly defensible attempt to guard against unauthorized reproduction may not be legal, but the industry has brought it on itself. By demanding that government socialize the costs of time-shifting reproduction through the AHRA, the RIAA welcomed this type of scrutiny. Contrast this situation to Microsoft Windows XP, which prevents multiple installations and other fair use(s). Microsoft is well within its legal rights to prevent unauthorized reproduction because its collects no royalties from blank diskette and CD-ROM sales. While public domain advocates may decry both practices, this distinction is not marginal. -------------------------------------------- Jason M. Thomas Economic Policy Analyst Citizens for a Sound Economy 1250 H Street NW, Suite 700 Washington, DC 20005-3908 phone: (202) 942-7621, fax: (202) 783-4687 www.cse.org ********* Date: Mon, 07 Jan 2002 13:49:03 -0500 From: Alan Ritzert <juggalo1@bellsouth.net> To: declan@well.com Subject: Re: FC: Rep. Boucher sends nastygram to music firms re: copy-protected CDs 1. A list of current known "corrupt CDs" can be obtained at http://www.fatchucks.com/corruptcds/corrupt.html 2. This isn't exactly detailed or too technical, but it's a link describing various methods of cd corruption. http://uk.eurorights.org/issues/cd/overview.shtml ********* Date: Mon, 7 Jan 2002 19:04:56 +0000 To: Declan McCullagh <declan@well.com> Cc: Martin Keegan <mk270@cam.ac.uk> Subject: Re: FC: Rep. Boucher sends nastygram to music firms re: copy-protected CDs Message-ID: <20020107190456.A32513@uazu.net> References: <5.1.0.14.0.20020107103428.029e6990@mail.well.com> <Pine.GSO.3.96.1020107171352.26534P-100000@virgo.cus.cam.ac.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit From: Jim Peters <jim@uazu.net> X-UIDL: d8ae2c02042ad1e688dc8afc3d200713 Martin Keegan wrote: > On Mon, 7 Jan 2002, Declan McCullagh wrote: > > > [Does anyone have a pointer to a detailed technical description of how the > > copy protection mechanism works? --Declan] > > Try the link "Dan Ackroyd's in-depth investigation of the Charlie Pride > CD's copy-protection" and some of the others on this page: > > http://uk.eurorights.org/issues/cd/docs/ Also check out my article on that page. About half-way down you'll find some links to NewScientist Online. These are by Barry Fox, and give good technical info. Although one of these was withdrawn under pressure from Midbar, the original patent is still viewable here: http://164.195.100.11/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=%276208598%27.WKU.&OS=PN/6208598&RS=PN/6208598 Here's a quote: > Thus, during playback, the substituted audio data portion 58 is > provided to the digital-to-analog converter as normal data, > resulting in audio distortion and POTENTIALLY DAMAGING THE OUTPUT > CIRCUITRY. What fun ! I should probably put that link into the article. (Okay, done). Cheers - Jim -- Jim Peters (_)/=\~/_(_) Uazú (_) /=\ ~/_ (_) jim@ (_) /=\ ~/_ (_) www. uazu.net (_) ____ /=\ ____ ~/_ ____ (_) uazu.net ********* Date: Mon, 7 Jan 2002 22:46:41 +0000 From: John Eisenschmidt <jweisen@eisenschmidt.org> To: Declan McCullagh <declan@well.com> Subject: Re: FC: Rep. Boucher sends nastygram to music firms re: copy-protected CDs Message-ID: <20020107224641.C4171@eisenschmidt.org> References: <5.1.0.14.0.20020107103428.029e6990@mail.well.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-md5; protocol="application/pgp-signature"; boundary="i7F3eY7HS/tUJxUd" Content-Disposition: inline Declan, CNET did a pretty good writeup in November: http://news.cnet.com/news/0-1005-200-7852921.html I saw this on Saturday on ZDNet, and I immediately wrote my Representative (Jim Moran) and asked him to join with Rep. Boucher and make the recording industry accountable for this. I've been extracted my CDs to MP3 since 1996, and I follow not only the letter of the law but the spirit. As soon as I get a CD it's extracted so I can listen at home, at work, in the car, and on my Rio. I don't have to carry hundreds of CDs with me everywhere, and I don't share my MP3s and I don't download copywrited music from the internet. Copywrited CDs stop me from enjoying the music I buy legally not only in preventing me from extracting them, but they don't play correctly in some CDROMs as well, meaning I can't listen to them anywhere. Sites like Fat Chucks http://fatchucks.mycool.com are trying to make people awar e that the recording industry is trying to slip this under the rug. You can't even return these CDs as defective, because most places only let you exchange defective music and videos for the same title (which is also "defective"). John Eisenschmidt ********* From: "D McOwen" <dmcowen@bellsouth.net> To: "Declan" <declan@well.com> Subject: So easy to put computer CD players in perpetual Error mode Date: Tue, 8 Jan 2002 00:20:58 -0500 Message-ID: <NCBBLLCKEFIGAFOKNBDLEEDPCIAA.dmcowen@bellsouth.net> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0002_01C197DA.58796520" X-Priority: 3 (Normal) X-MSMail-Priority: Normal Declan, It's so easy it's not funny. It is just as I thought. You simply put the CD in perpetual Error Mode for a Computer type CD player by purposely burning a track error in. That is just outright mean. I put in BOLD (continue the pattern) down below where the intentional errors would affect a computer player but not a music only player. <http://www.ee.washington.edu/conselec/CE/reports/Group.1/matt_page_individual/subcode.html>http://www.ee.washington.edu/conselec/CE/reports/Group.1/matt_page_individual/subcode.html SUBCODE ON THE COMPACT DISK Did you ever wonder just how a CD player new exactly where it was on the disk at all times, even if it skipped? Did you ever think about how some CD players know the name of the disk before you even play a song? These and other similar little tricks are done with a portion of the CD's data called subcode. Out of every 291 bits of data that come off the disk, 8 of them are devoted to this subcode. The 8 bits are given letters designating their usage: P, Q, R, S, T, U, V and W. Most players actually only use the Q bit. The Q bit You might be wondering how much usefull information can be derived from just one bit? Well, the CD player gets around this apparantly small amount of data by waiting until 98 of these bits have been received and then decoding the information. It would be like you sending a letter to your friend one character at a time. This all happens so quickly though that an entire 98 bit block (called a subcode block) is available 75 times every second. It doesn't seem like such a small amount of data now, does it? Within the Q channel (or the Q subcode block) there are basically 4 types of information: Data, Control, Address, and some Error Detection Code. The format of the Q channel is seen in the diagam below: figure 3.30 There are 4 bits devoted to control information. The first bit tells the CD player whether the CD has 2 or 4 audio channels. Although no CD player I've seen has 4 channels output, it might be the next advance in the technology. Imagine listening to a live concert with all the real depth and sound surrounding you. Currently the closest thing to this is to use DSP to delay a copy of the 2 channel signal (along with some fancy processing) and send it to the rear speakers. Using all four channels of the CD as it is capable of would sound much more realistic. The second bit isn't defined. The third bit is used for a sort of copy protection. If the bit is set, it tells a digital recorder listening to the data not to record. This is why a DAT wont record all of your CD's so you can take them back and not have to pay for them. Record companies thought about this in advance... The fourth bit of the control is to indicate whether or not the CD was recorded using pre-emphasis. Pre-emphasis in CD players works a lot like the original dolby noise reduction techniques used to get better quality recordings on analog tapes. The process stems from the idea that most of the noise in a recording occurs in the high end of the frequency spectrum. The master recording (usually a tape) is assumed to be without noise or distortion. The high frequencies are amplified and then recorded onto the CD disk. The recording process introduces a little noise in the high end, which would be the same amount whether or not the original signal was amplified. The CD player playing the recorded disk reads off the music and attenuates the high end frequencies, reducing the noise from the recording process greatly and returning the signal back to its proper level of amplification. If the manufacturer of the disk used this pre-emphasis process, the fourth bit of the control would be set to 1, telling the CD player to turn on the de-emphasis circuit to perform the attenuation. After the control information in the Q channel comes 4 bits of address information. These 4 bits tell the CD player what to look for in the next block in the Q channel (the Data block). There are 3 different varieties of Data blocks, mode 1, mode2 and mode3. The 4 bits of address indicate which of the three types the Data block is. Data block mode 1 The information in the Data block when it is in mode 1 is different depending upon whether or not you are in the "lead-in" area. The lead-in area is the first area on a disk and gives such information as the table of contents for a disk. The format of the Data block when it is in mode 1 is shown below: figure 3.31 The lead-in area is indicated by the first TNO field being 8 bits of zeros. When in the lead-in area, the Point field specifies a track number, from 0 to 99. The Min, Sec and Frame fields give the absolute starting time of that track from the end of the lead in area in Minutes, Seconds and Frames respectively (there are 75 frames in a second). If the Point field has the hexadecimal number A0 in it, the Min field contains the number of the first track, with the Sec and Frame fields set to zero. If it contains and A1, the Min field contains the number of the last track on the disk. Finally, if the Point field has an A2, the Min, Sec and Frame fields give the absolute time of the end of the music (which would indicate total disk play time). The Q-channel in the lead-in area is repeated 3 times for every entry in the table of contents to introduce redundancy in case of errors. The Q-channels as they come of the disk would give data like this: Track 1 start time, Track 1 start time, Track 1 start time, Track 2 start time, Track 2 start time, Track 2 start time ... ... Track 99 start time, Track A0 info, Track A0 info, Track A0 info, Track A1 info ... and so on. When the disk is in the program area, that is when it's playing songs, the data area in mode 1 contains the current track number, the amount of time since the beginning of the track, the amount of time from the beginning of the CD, and 8 bits which can be used to indicate indexes in the track, like bookmarks. Up to 99 indexes can be encoded in each track. Using this data, your CD player gives you a readout on the display of how many seconds have elapsed, what track you're on etc. Because this information is encoded right along with the music, you can skip the CD to a completely new area, and it will always tell you exactly where it is on the CD. Data block mode 2 and mode 3 When the Data block is in mode 2 or 3 (indicated by a 2 or 3 in the 4 bits of address in the Q channel), different information can be obtained, as can be seen in the breakdown of the Q-channel below: [] The data in mode 2 contains a sort of bar-code for the disk. It's a catalog number which uniquely identifies the disk and it remains constant for every mode 2 data block. This is how some CD players know the name of the disk. They read the disk to get the catalog number and looks it up in a table which maps catalog number to name of disk. The table is usually built by the user. All the user has to do is to type in what the disk should be referred to the first time it gets put into the CD player. Other usefull things can arise from the catalog nuber besides disk names, one can program in their favorite songs and put that in memory as well. When one plays the disk again, all the favorites are ready to go. Mode 3 (if present) has a little more detail about the origin of the disk. It contains a code for the recording which indicates the country, owner, year of recording and a serial code. This data can change from track to track as the information refers to the particular song and not necessarily to the whole disk. ------------------------------------------------------------------------- POLITECH -- Declan McCullagh's politics and technology mailing list You may redistribute this message freely if you include this notice. Declan McCullagh's photographs are at http://www.mccullagh.org/ To subscribe to Politech: http://www.politechbot.com/info/subscribe.html This message is archived at http://www.politechbot.com/ -------------------------------------------------------------------------