Content-Digest
The HTTP Content-Digest header provides a digest of the message content in an HTTP message.
As such, Content-Digest is dependent on among other things Content-Encoding and Content-Range, but not dependent on, for example, HTTP/1.1's Transfer-Encoding.
Content-Digest may coincide with Repr-Digest if a representation was sent in a single message.
In this setting, content refers to a particular octet representation of the selected representation of the target resource.
A client can request that a server emit a Content-Digest by issuing Want-Content-Digest.
| Header type | Request header, Response header, Representation header |
|---|---|
| Forbidden header name | No |
Syntax
Content-Digest describes an RFC8941 dictionary with its keys being names of digest algorithms and its values being the digest in bytes (or an integer digest for legacy digest algorithms).
Note:
In contrast to earlier drafts of the specification, the standard-base64-encoded digest bytes are wrapped in colons (:, ASCII 0x3A) as part of the dictionary syntax.
Content-Digest: <digest-algorithm>=:<standard-padded-base64-digest-value>:, ...
Content-Digest: <digest-algorithm-integer-checksum>=<integer-checksum-value>, ...
Directives
For permissible digest algorithms see Repr-Digest.
Examples
Content-Digest: unixcksum=916142062 Content-Digest: md5=:+thA//8pGVGk2VYuJkFNvA==:, unixsum=26869
Specifications
| Specification |
|---|
| Digest Fields |
Browser compatibility
This header has no specification-defined browser integration ("browser compatibility" does not apply).
Developers can set and get HTTP headers using fetch() in order to provide application-specific implementation behavior.