techtrends By Brian Dipert, Technical Editor RAMPANT PIRACY OF UNPROTECTED DIGITAL MEDIA HAS CONTENT DEVELOPERS AND DISTRIBUTORS SCRAMBLING TO CONSTRAIN, REDEFINE, AND EXPLOIT THIS “NEW WORLD ORDER.” IN DEVELOPING YOUR MEDIA-RECORDING AND -PLAYBACK DEVICES, BEWARE OF CREEPING SECURITY ELE- GANCE THAT, LEFT UNCHECKED, WILL GIVE RISE TO GADGETS NOBODY WANTS—OR CAN FIGURE OUT HOW—TO USE. Media security thwarts temptation, permits prosecution umerous lawsuits, some of which have already returned ver- Illustration by Daniel Guidera Ndicts against the defendants, attempt to curtail the illegal dis- tribution of copyright-protected digital media, such as electronic books, still images, audio files, and video movies. Rock band Metal- lica and rap artist Dr Dre have even taken the unusual step of pur- suing legal action not only against a software company whose prod- uct supposedly promotes such content-sharing, but also against several universities whose students swap because its servers don’t host the files, it’s files using the school-supplied comput- not responsible for illegal use of its soft- er networks. Consortiums such as the ware. Gnutella is a similar program de- Recording Industry Association of Amer- veloped by Justin Frankel, the originator At a glance ............................102 ica (RIAA) and Motion Picture Associa- of the popular Nullsoft WinAmp MP3 Back to basics ........................104 tion (MPA) are frantically developing se- player. Gnutella extends access and ex- curity standards to protect their tra- change to any type of file (including, un- Belatedly closing ditional revenue streams as e-stores re- fortunately, pornography); uses a direct Pandora’s box ......................106 place brick-and-mortar and as electrons peer-to-peer network connection instead Securing—and circum- replace paper, plastic, magnetic tape, and of a central director server; was released venting—at high speed ......108 silver-halide film. What’s all the fuss in open source this spring (to the con- For more information ..........116 about? sternation of Nullsoft’s purchaser,Amer- Napster, which lets Internet-connect- ica Online); and has spread throughout ed users view and download MP3 files the Internet in dozens of mutations. stored on other computers, boasts mil- Scour.net’s Scour Exchange and pro- lions of registered users and claims that grams such as CuteMX, FreeNet, iMesh, www.ednmag.com June 22, 2000 | edn 101 techtrends Digital-media security and VBGnutella offer similar features. images, portable MP3 and MiniDisc College students, who historically pur- AT A GLANCE players are obsoleting analog tape, and chase a significant percentage of audio e Burgeoning digital text, audio, and digital speakers and high-definition-TV CDs and videotapes, have enjoyed speedy video media combine with high-speed displays are establishing footholds in broadband Internet access for years, Internet access, high-performance com- homes. thanks to their university accounts.With puters, and cheaper and denser storage In attempting to stem the flood of il- ADSL (asymmetrical-digital-subscriber- to create a piracy potential that gives legal media sharing, the content creators line) and cable modems now entering Hollywood nightmares. and distributors and you, their equip- homes in a big way, even more traditional ment-manufacturer partners, must walk music and video consumers can quickly e When evaluating security algorithms a thin line. On the one hand, you’re en- download and stream multimegabyte for incorporation within your systems, be forcing the valid copyright claims of files. sure to balance robustness with ease of those who developed the material. How- Where are these files coming from? To- use and performance. ever, you can’t excessively constrain cus- day’s high-powered PCs can achieve bit- tomers who are exercising their legal accurate extraction of CD audio content e Don’t let the content developers’ and rights to make copies for their own use of and compress it to one-twelfth (MP3) or distributors’ fear and greed lead you to media they own and to transfer owner- even one-twenty-fourth (MS Audio) its implement features that circumvent privacy ship of that purchased media to others. original size with little-to-no discernible or restrictions that violate consumers’ Media-security, or DRM (digital-rights- quality loss (Reference 1). Both extrac- duplication and transfer rights for their management) systems should be invisi- tion and compression occur several times legally obtained media. ble to honest users (this invisibilty is faster than ordinary playback speeds, and called “eliminating false positives”), while digital copies retain much higher quali- e An ideal security system combines the acting as strong deterrents to pirates. ty than bootlegs made in the analog past. concepts of authentication, encryption, and And, to simplify your implementation, Multigigabyte hard drives are now per- renewability. one or only a few DRM systems are de- vasive, as are fast-writing CD-recordable sirable, though recent trends point to an drives. Rapid encoding and transcoding DVD, albeit with some audio- and video- explosion of alternatives. The IEC (In- of video streams are now within the quality loss, can fit onto a CD. Large- ternational Electrotechnical Commis- reach of computer users. Courtesy of screen, high-resolution computer mon- sion) is attempting to standardize a programs such as DeCSS, a transcoded itors can easily display high-definition means of coping with this diversity of op- Figure 1 ADSL, CABLE MODEM, SATELLITE DVI S/PDIF, USB BLUETOOTH, ETHERNET, HOMEPNA, HOMERF, IEEE 1394, IEEE 802.11, POWERLINE, S/PDIF, USB High-speed digital interconnections both to and within homes transform into reality The Jetsons creators’ cartoon vision of the future, but they also raise serious security concerns. 102 edn | June 22, 2000 www.ednmag.com techtrends Digital-media security BACK TO BASICS People often use the terms speed encoding and decoding, the key-generation, encryption, libraries) and ActiveX controls; and “encryption” and “watermarking” which occurs because the algo- and decryption algorithms, com- an ANSI-standard C library for interchangeably. In truth, the rithms employ relatively simple monly based on prime-number embedded systems. Tested com- terms refer to different technolo- transposition and substitution techniques, require multiplication pilers include Visual C++, Borland gies, although both are important steps. The Achilles’ heel of the operations that are time-consum- C++, and Gnu/g++. One other aspects of a comprehensive digi- approach, though, is the common ing and performance-intensive. unique attribute of the tal-rights-management system, key, which the source must trans- Asymmetric encryption examples Encryptonite approach is RPK’s and you can sometimes use mit to the destination via a secure include the RSA (Rivest, Shamir, assertion that, aside from greater watermarking to implement channel or a trusted third party. If and Adelman) and Diffie-Helman initial latency analogous to a FIFO- encryption. something intercepts the bit algorithms. buffer fill, increased key length Two main types of encryption stream and the unintended recipi- Hybrid schemes that combine does not degrade performance. exist. Symmetrical, or synchro- ent figures out the key, the media asymmetric and symmetric en- The company is developing hard- nous, encryption uses the same is vulnerable. On the other hand, cryption, such as a combination of ware-based encryption and security key to “lock” and scram- clever encryption can result in the RSA and DES, are also possible. decryption accelerators to supple- ble an outgoing file and to recover delivery of a legitimate-appearing Consider, for example, the ment its software offerings. a bit-exact copy of the original but incorrect piece of media, such approach that HDCP (High-band- PassEdge’s StreamAccess en- content at the destination. Exam- as a bogus memo, to a recipient width Digital Copy Protection) cryption algorithms take advan- ples of symmetrical encryption using an invalid key. takes. Asymmetric encryption tage of any hardware-accelerated include the now-broken DES Asymmetric, or asynchronous, establishes the initial authorization integer arithmetic logic within a (Data Encryption Standard); its encryption employs dual keys between host and display, as well microprocessor, such as Intel’s interim replacement, triple-DES, (Figure A). The sender encrypts as the periodic reauthorization. MMX (multimedia-extensions) which, as the name implies, runs the media with the recipient’s Faster symmetric compression instruction set. The company tar- each data packet through DES public key, and the recipient handles the content transfer. Any geted a 166-MHz Pentium CPU for encryption three times; next-gen- decrypts it with his or her private performance-critical application its client-side security software and eration AES (Advanced Encryption key. Exchange of public keys can incorporate a similar estimates that with a less-than-1- Standard); and RC (Rivest’s requires no secure channel, and approach. DTCP (Digital Trans- Mbyte memory footprint, includ- Cipher). The primary advantage of the recipient can ensure authenti- mission Copy Protection) compre- ing a graphical user interface, the symmetrical encryption is its high- cation of a valid sender. However, hends support for both asymmet- device will consume no more than ric and symmetric protocols. It 3% of a 450-MHz Pentium II CPU Figure A supports symmetric