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title slug page-type status browser-compat
Want-Digest
Web/HTTP/Headers/Want-Digest
http-header
deprecated
non-standard
http.headers.Want-Digest

{{HTTPSidebar}}{{Deprecated_Header}}{{non-standard_header}}

Note

This header was removed from the specification in draft 8. Use {{HTTPHeader("Want-Content-Digest")}} instead. For id-* digest algorithms, use {{HTTPHeader("Want-Repr-Digest")}}.

The Want-Digest request or response HTTP header requests the other side to provide a {{Glossary("digest")}} using the {{HTTPHeader("Digest")}} header.

The header contains identifiers for one or more digest algorithms that the sender wishes the server to use to create the digest. The request may use {{Glossary("quality values")}} to indicate its preference/order for particular digest algorithms.

If Want-Digest does not include any digest algorithms that the server supports, the server may respond with:

  • a digest calculated using a different digest algorithm, or
  • a 400 Bad Request error, and include another Want-Digest header with that response, listing the algorithms that it does support.

See also the {{HTTPHeader("Digest")}} header.

Header type {{Glossary("Request header")}}, {{Glossary("Response header")}}
{{Glossary("Forbidden header name")}} no

Syntax

Want-Digest: <digest-algorithm>

// Multiple algorithms, weighted with the quality value syntax:
Want-Digest: <digest-algorithm><q-value>,<digest-algorithm><q-value>

Directives

  • <digest-algorithm>
    • : Digest algorithms are defined in Digest Headers.
      • Permitted digest algorithms values include: unixsum, unixcksum, crc32c, sha-256 and sha-512, id-sha-256, id-sha-512
      • Deprecated algorithms values include: md5, sha, adler32.
  • <q-value>

Examples

Want-Digest: sha-256
Want-Digest: SHA-512;q=0.3, sha-256;q=1, md5;q=0

Basic operation

The sender provides a list of digests which it is prepared to accept, and the server uses one of them:

Request:

GET /item
Want-Digest: sha-256;q=0.3, sha;q=1

Response:

HTTP/1.1 200 Ok
Digest: sha-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=

Unsupported digests

The server does not support any of the requested digest algorithms, so uses a different algorithm:

Request:

GET /item
Want-Digest: sha;q=1

Response:

HTTP/1.1 200 Ok
Digest: sha-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=

The server does not support any of the requested digest algorithms. In this case it responds with a 400 error and includes another Want-Digest header, listing the algorithms that it does support:

Request:

GET /item
Want-Digest: sha;q=1

Response:

HTTP/1.1 400 Bad Request
Want-Digest: sha-256, sha-512

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

  • {{HTTPHeader("Digest")}}