The HTTPWant-Repr-Digestrequest andresponse header indicates a preference for the recipient to send aRepr-Digest integrity header in messages associated with the request URI and representation metadata.

The header includes hashing algorithm preferences that the recipient can use in subsequent messages.The preferences only serve as a hint, and the recipient may ignore the algorithm choices, or the integrity headers entirely.

Some implementations may send unsolicitedRepr-Digest headers without requiring aWant-Repr-Digest header in a previous message.

Syntax

Want-Repr-Digest: <algorithm>=<preference>Want-Repr-Digest: <algorithm>=<preference>, …, <algorithmN>=<preferenceN>

Directives

<algorithm>

The requested algorithm to create a digest of the representation.Only two registered digest algorithms are considered secure:sha-512 andsha-256.The insecure (legacy) registered digest algorithms are:md5,sha (SHA-1),unixsum,unixcksum,adler (ADLER32) andcrc32c.

<preference>

An integer from 0 to 9 where0 means "not acceptable", and the values1 to9 convey ascending, relative, weighted preference.In contrast to earlier drafts of the specifications, the weighting isnot declared viaqquality values.

Examples

Want-Repr-Digest: sha-512=8, sha-256=6, adler=0, sha=1Want-Repr-Digest: sha-512=10, sha-256=1, md5=0

Specifications

Browser compatibility

This header has no specification-defined browser integration ("browser compatibility" does not apply).Developers can set and get HTTP headers usingfetch() in order to provide application-specific implementation behavior.

See also

• Content-Digest,Repr-Digest,Want-Content-Digest digest headers
• Digital Signatures for APIs SDK guide usesContent-Digests for digital signatures in HTTP calls (developer.ebay.com)