The primary value of the DCI specification for digital cinema is security. DCI devotes nearly half of its 155 page document to the subject of security, specifying in great detail how the various elements in a digital cinema system are to be constructed and how they must behave from a security point-of-view. A cornerstone of the DCI specification is its reliance on voluntary specifications established by the US Federal Information Processing Standards (FIPS). In August, the US National Institute of Standards and Technology (NIST) issued a request for public comment to reference or possibly replace in entirety the FIPS 140-2 specification, relied upon by DCI, with the ISO/IEC 19790:2012 specification.
Security requirement updates are driven by the growing power and availability of computers, and weaknesses that may have been discovered along the way in existing practice. An update to the FIPS 140-2 specification, following the initial rollout of digital cinema, led to the revised requirement for media blocks to carry two certificates. The public/private keys of one certificate to be used for KDMs, while the public/private keys of the other certificate to be reserved for TLS sessions. In the original specification for digital cinema, the same set of public/private keys were used for both functions. Changes in FIPS 140-2 also led to changes in how content integrity is checked within the media block, and an accompanying change in requirements for the KDM. Importantly, changes in security practices in digital cinema are driven by outside organizations whose expertise is security, and not from within the cinema industry.
One of the benefits of relying on an expert standard is that it opens the door to the use of expert testing laboratories worldwide. While FIPS 140-2 is a US standard, testing laboratories around the world are expert in applying the standard when evaluating performance of real equipment. Presumably, many or all of these testing laboratories also conduct tests in accordance with ISO/IEC 19790:2012.
NIST began drafting the revised standard FIPS 140-3 in 2005, just as the digital cinema rollout began. But progress in the development of 140-3 suffered, and was never formally released. In contrast, ISO/IEC 19790 was first published in 2006, largely containing the requirements of FIPS 140-2. ISO/IEC 19790 continued to develop into the 2012 version now in use today, reportedly incorporating features of draft 140-3. ISO/IEC 19790 is not an isolated standard, and unless the differences are substantial, it would seem logical to embrace a single international effort.
DCI believes there will be no impact on digital cinema if the standard moves to ISO/IEC. For digital cinema, the largest difference found so far, somewhat humorously, is the allowance in ISO/IEC of translucent enclosures. For those who have always wanted to peek inside the secure boundary of a media block, this could be your chance.
