Digital Copy Protection System (DCPS)
In order to provide digital connections between components without allowing perfect digital copies, five digital copy protection systems were proposed to the CEA. The frontrunner is DTCP (digital transmission content protection), which focuses on IEEE 1394/FireWire but can be applied to other protocols. The draft proposal (called 5C, for the five companies that developed it) was made by Intel, Sony, Hitachi, Matsushita, and Toshiba in February 1998. Sony released a DTCP chip in mid 1999. Under DTCP, devices that are digitally connected, such as a DVD player and a digital TV or a digital VCR, exchange keys and authentication certificates to establish a secure channel. The DVD player encrypts the encoded audio/video signal as it sends it to the receiving device, which must decrypt it. This keeps other connected but unauthenticated devices from stealing the signal. No encryption is needed for content that is not copy protected. Security can be “renewed” by new content (such as new discs or new broadcasts) and new devices that carry updated keys and revocation lists (to identify unauthorized or compromised devices). A competing proposal, XCA (extended conditional access), from Zenith and Thomson, is similar to DTCP but can work with one-way digital interfaces (such as the EIA-762 RF remodulator standard) and uses smart cards for renewable security. Other proposals have been made by MRJ Technology, NDS, and Philips. In all five proposals, content is marked with CGMS-style flags of “copy freely”, “copy once,” “don’t copy,” and sometimes “no more copies”. Digital devices that do nothing more than reproduce audio and video will be able to receive all data (as long as they can authenticate that they are playback-only devices). Digital recording devices are only able to receive data that is marked as copyable, and they must change the flag to “don’t copy” or “no more copies” if the source is marked “copy once.” DCPSes are designed for the next generation of digital TVs, digital receivers, and digital video recorders. They require new DVD players with digital connectors (such as those on DV equipment). These new products began to appear in 2003. Since the encryption is done by the player, no changes are needed to existing discs.