Re: An HTTP digest for PATCHing?

Hello Lucas,

Thank you for writing this useful draft! It nicely addresses an area that isn't covered by the existing digest fields.

One caveat might be the issue of normalization. When the client wants to include the Patched-Digest header field, it has to know the exact byte values for the patched representation. This might not be possible in all cases, for example, when patching a JSON document using JSON Patch (RFC 6902). Depending on the handling of whitespace and property ordering, the patch could produce multiple valid representations. Unless the client is somehow aware of how exactly the server applies a PATCH, it might be difficult to anticipate the correct Patched-Digest. Normalization could help here, but it's not always defined.

Now, I don't think there is much you can do in this document in that regard other than stating this potential issue and encouraging authors of future content types for patch documents to take this into consideration.

Best regards,
Marius

On Mon, Jul 20, 2026, at 13:51, Lucas Pardue wrote:
> I posted a minimally scoped I-D for the patch use case (see below)
> 
> ----- Original message -----
> From: internet-drafts@ietf.org
> To: Lucas Pardue <lucas@lucaspardue.com>
> Subject: New Version Notification for draft-pardue-httpbis-patched-digest-00.txt
> Date: Monday, July 20, 2026 12:46
> 
> A new version of Internet-Draft draft-pardue-httpbis-patched-digest-00.txt has
> been successfully submitted by Lucas Pardue and posted to the
> IETF repository.
> 
> Name:     draft-pardue-httpbis-patched-digest
> Revision: 00
> Title:    HTTP Patched Digest
> Date:     2026-07-20
> Group:    Individual Submission
> Pages:    10
> URL:      https://www.ietf.org/archive/id/draft-pardue-httpbis-patched-digest-00.txt
> Status:   https://datatracker.ietf.org/doc/draft-pardue-httpbis-patched-digest/
> HTML:     https://www.ietf.org/archive/id/draft-pardue-httpbis-patched-digest-00.html
> HTMLized: https://datatracker.ietf.org/doc/html/draft-pardue-httpbis-patched-digest
> 
> 
> Abstract:
> 
>    The PATCH method can be used to apply partial modifications to a
>    resource.  This document defines the Patched-Digest request field,
>    which allows a client to indicate the integrity digest of the
>    modified resource once a PATCH operation is applied.  A server can
>    use the integrity digest to detect an operation failure and return an
>    error.  The Want-Patched-Digest response field is also defined to
>    signal server integrity preferences.
> 
> 
> 
> The IETF Secretariat
> 
> 
> 
>