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, localised 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.

Digest: <digest-algorithm>=<digest-value>
Digest: <digest-algorithm>=<digest-value>,<digest-algorithm>=<digest-value>

<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.

<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.

• Want-Digest
• HTTP range requests
• 206 Partial Content