Digital Transmission Content Protection ( DTCP ) is a digital rights management (DRM) technology that restricts digital home technologies including DVD players and televisions by encrypting interconnections between devices. This permits the distribution of content through other devices such as personal computers or portable media players , if they also implement the DTCP standards. DTCP has also been referred to as "5C" content protection, a reference to the five companies that created DTCP; Hitachi , Intel , Matsushita , Sony , and Toshiba .
7-816: The standard was originally proposed in February 1998, when the five companies presented the system to the Copy Protection Technical Working Group (CPTWG), an ad hoc body organized to evaluate DRM technologies. The five companies subsequently established the Digital Transmission Licensing Administrator (DTLA) in June 1998 to simplify licensing procedures and promote acceptance of the DTCP method by content providers, electronics manufacturers, and broadcast service providers. They also released
14-470: A move to using TCP/IP carried on high-speed ethernet and WiFi connections to replace FireWire and similar systems, a move epitomized by the Apple TV . The DTCP standard has branched out to cover a variety of media types to respond to these industry changes, and now supports USB , IP , WiFi , Bluetooth and MOST (a media standard for automotive platforms) in addition to FireWire. The DTCP specification
21-425: A partial description of the algorithm based on a draft standard is given by Kelsey, et al. in their cryptanalysis of this family of ciphers. The algorithm operates on blocks of 64 bits using a 10-round Feistel network structure. The key size is 40 bits by default, but can be up to 64 bits. The key schedule is very simple, producing two 32-bit subkeys: the high 32 bits of the key , and the sum mod 2 of this and
28-461: Is proprietary and is only disseminated to members, who agree to the DTLA agreements (some fees need to be paid to even get the specification). An "informational version" of the specification, omitting some critical details of the implementation, is freely available. In November 2010 the Digital Transmission Licensing Administrator proposed enhancements to DTCP known as DTCP+. This enhanced specification
35-493: The 5C Digital Transmission Content Protection White Paper describing the system. The paper specifies Hitachi's M6 cipher as the baseline encryption system, which was already in widespread use in the Japanese cable industry. At the time, FireWire was widely regarded as the up-and-coming standard for interconnecting media devices, although this has not been widely adopted in the decade following. More recently there appears to be
42-513: The low 32 bits. Because its round function is based on rotation and addition, M6 was one of the first ciphers attacked by mod n cryptanalysis . Mod 5, about 100 known plaintexts suffice to distinguish the output from a pseudorandom permutation . Mod 257, information about the secret key itself is revealed. One known plaintext reduces the complexity of a brute force attack to about 2 trial encryptions; "a few dozen" known plaintexts lowers this number to about 2 . Due to its simple key schedule, M6
49-509: Was due to be completed in January 2011. DTCP+ adds the following capabilities: M6 (cipher) In cryptography , M6 is a block cipher proposed by Hitachi in 1997 for use in the IEEE 1394 FireWire standard. The design allows some freedom in choosing a few of the cipher's operations, so M6 is considered a family of ciphers. Due to export controls, M6 has not been fully published; nevertheless,
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