Reverse Engineering Digital Cinema Security: An Expired Certificate's Tale
2025-04-20
Late 2023, the movie 'Wonka' couldn't play in some cinemas due to an expired distributor certificate. This sparked a cinema operator's curiosity, leading to a deep dive into the Digital Cinema Initiatives (DCI) standard and its movie encryption. The article details the DCI workflow, DCP file format, KDM/DKDM key distribution, and MXF file encryption. While decryption is complex, involving AES-128, RSA signatures, and unique IVs, the author believes the DCI standard itself is secure, relying on unique keys and protected private keys. Open-source libraries and tools are mentioned, along with how distributors use a trusted device list to protect content.
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