This document specifies common encryption formats for use in any file format based on ISO/IEC 14496-
12. File, item, track, and track fragment metadata is specified to enable multiple digital rights and key
management systems (DRMs) to access the same common encrypted file or stream. This document
does not define a DRM system.
The AES-128 symmetric block cipher is used to encrypt elementary stream data contained in media
samples. Both AES counter mode (CTR) and Cipher Block Chaining (CBC) are specified in separate
protection schemes. Partial encryption using a pattern of encrypted and clear blocks is also specified
in separate protection schemes. The identification of encryption keys, initialization vector storage and
processing is specified for each scheme.
Subsample encryption is specified for NAL structured video, such as AVC and HEVC, to enable normal
processing and editing of video elementary streams prior to decryption.
An XML representation is specified for important common encryption information so that it can be
included in XML files as standard elements and attributes to enable interoperable license and key
management prior to media file download.