This specification defines the "keyids" Initialization Data format for use with the Encrypted Media Extensions [ENCRYPTED-MEDIA].


It defines a stream format-independent format for specifying a list of key ID(s). This type can be used by applications to directly provide information necessary to generate a license request without using media data or constructing container-specific formats.

Status of This Document

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This document was published by the HTML Media Extensions Working Group as a Working Group Note. If you wish to make comments regarding this document, please send them to public-html-media@w3.org (subscribe, archives). All comments are welcome.

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1. Format

The format is a JSON object, encoded in UTF-8 as specified in the Encoding specification [encoding], containing the following member:

An array of key ID(s). Each element of the array is the base64url encoding of the octet sequence containing the key ID value.

See Using base64url.


Applications may encode the JSON string using the TextEncoder interface [encoding]

2. Example

This section is non-normative.

The following example will generate a license request for two key ID(s). (Line breaks are for readability only.)

Example 1

A. References

A.1 Normative references

David Dorwin; Jerry Smith; Mark Watson; Adrian Bateman. W3C. Encrypted Media Extensions. 5 July 2016. W3C Candidate Recommendation. URL: https://www.w3.org/TR/encrypted-media/
Anne van Kesteren; Joshua Bell; Addison Phillips. W3C. Encoding. 20 October 2015. W3C Candidate Recommendation. URL: https://www.w3.org/TR/encoding/