Digest
The Digest
response HTTP header provides a digest of the selected representation of the requested resource.
Representations are different forms of a particular resource that might be returned from a request: for example, the same resource might be formatted in a particular media type such as XML or JSON, localized to a particular written language or geographical region, and/or compressed or otherwise encoded for transmission. The selected representation is the actual format of a resource that is returned following content negotiation, and can be determined from the response's Representation headers.
The digest applies to the whole representation of a resource, not to a particular message. It can be used to verify that the representation data has not been modified during transmission.
Note: While a representation may be fully contained in the message body of a single response, it can also be sent using multiple messages in response to a range request, or omitted altogether in response to a HEAD
request.
Header type | Response header |
---|---|
Forbidden header name | no |
Syntax
Digest: <digest-algorithm>=<digest-value> Digest: <digest-algorithm>=<digest-value>,<digest-algorithm>=<digest-value>
Directives
<digest-algorithm>
-
Digest algorithms are defined in Digest Headers.
- Permitted digest algorithms values include:
unixsum
,unixcksum
,crc32c
,sha-256
andsha-512
,id-sha-256
,id-sha-512
- Deprecated algorithms values include:
md5
,sha
,adler32
.
- Permitted digest algorithms values include:
<digest-value>
-
The result of applying the digest algorithm to the resource representation and encoding the result. The choice of digest algorithm also determines the encoding to use: for example
SHA-256
uses base64 encoding.
Examples
Digest: sha-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
Digest: sha-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=,unixsum=30637
Specifications
Specification |
---|
Unknown specification # section-3 |
Browser compatibility
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