What is CENC Encryption?
Common Encryption (CENC) specifies a shared way to encrypt media in ISO Base Media File Format containers. The resulting segments can be used with multiple compatible digital rights management systems.
How CENC Encryption works
CENC separates encrypted sample storage from the DRM-specific license exchange used by a player. Encryption metadata in an ISO Base Media File Format package identifies protected tracks, key identifiers, and the scheme needed to decrypt samples, while system-specific initialization data can accompany the presentation. It fits between encoding and streaming packaging, enabling compatible players to consume common media bytes even though their license protocols and DRM implementations differ.
Key facts
- A key identifier selects the content key but is not the secret key itself. Packages and license services must agree on that mapping or decryption fails after successful manifest loading.
- The
cencscheme uses counter-mode sample encryption, whilecbcsuses pattern-based cipher-block chaining; device and DRM support must match the scheme chosen during packaging. - CENC defines media encryption and signaling, not viewer entitlement or license policy. A valid package still needs a compatible DRM client and reachable license service.
When CENC Encryption matters
Choose CENC when one DASH or CMAF package must serve players that rely on different DRM providers. Player, encryption scheme, and key-management compatibility must still be verified.