How encryption for Cinema Movies works

a year ago

The DCI (Digital Cinema Initiatives) specification defines standards for secure movie distribution, including file formats, encryption, and projection systems.
DCP (Digital Cinema Package) contains all movie components (metadata, subtitles, audio, and video) in separate files, encrypted with a static AES-128 key.
KDM (Key Delivery Message) is an XML file containing cryptographic information to decrypt a DCP for playback on a specific projector.
The distribution process involves encrypted AES keys, certificate chains (Root CA, Intermediate CA, Leaf Certificate), and trusted device lists.
Projection systems consist of a server, audio processor, and projector, with a 'Media Block' handling DRM and decryption in real-time.
DCPs are stored encrypted and can be imported via USB/CRU hard drives or internet download.
MXF (Material Exchange Format) files are used for movie frames, encrypted with AES-128 and unique IVs (Initialization Vectors) per frame.
DCI compliance ensures security through unique AES keys per DCP, TPM-like hardware for key storage, and distributor verification of projector certificates.
DCI v1.4.4 now allows playback of DCPs with expired signer certificates, with manufacturers working on updates.
Open-source tools like DCP-o-matic and asdcplib are used for DCP creation and decryption.

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