Re: I-D Action: draft-ietf-httpbis-digest-headers-12.txt

Hi,

I'm a little confused by the last paragraph of Section 6.4: Usage in
Trailer Fields.

> Not every hashing algorithm is suitable for use in the trailer section,
some may
> require to preprocess the whole content before sending a message (e.g.,
see [I-D.thomson-http-mice]).

Firstly, there's a small grammar problem with "require to...". But that's
not my main concern.

Isn't the point of using a trailer to work around those algorithms that
require processing all of the content?

For example, the code samples for Python's "hashlib" show SHA-256:
https://docs.python.org/3/library/hashlib.html

Presumably, you'd call the update() method as you put bits on the wire, and
then put the result of digest() in the trailer.

draft-thomson-http-mice-02 would seem to address issues with "eager
processing" that the document covered in the previous paragraph.

Anyway, I think there's something to fix here, even if I am confused about
the technical issue.

thanks,
Rob




On Thu, Apr 13, 2023 at 7:54 AM <internet-drafts@ietf.org> wrote:

>
> A New Internet-Draft is available from the on-line Internet-Drafts
> directories. This Internet-Draft is a work item of the HTTP (HTTPBIS) WG of
> the IETF.
>
>    Title           : Digest Fields
>    Authors         : Roberto Polli
>                      Lucas Pardue
>    Filename        : draft-ietf-httpbis-digest-headers-12.txt
>    Pages           : 41
>    Date            : 2023-04-13
>
> Abstract:
>    This document defines HTTP fields that support integrity digests.
>    The Content-Digest field can be used for the integrity of HTTP
>    message content.  The Repr-Digest field can be used for the integrity
>    of HTTP representations.  Want-Content-Digest and Want-Repr-Digest
>    can be used to indicate a sender's interest and preferences for
>    receiving the respective Integrity fields.
>
>    This document obsoletes RFC 3230 and the Digest and Want-Digest HTTP
>    fields.
>
> The IETF datatracker status page for this Internet-Draft is:
> https://datatracker.ietf.org/doc/draft-ietf-httpbis-digest-headers/
>
> There is also an HTML version available at:
> https://www.ietf.org/archive/id/draft-ietf-httpbis-digest-headers-12.html
>
> A diff from the previous version is available at:
>
> https://author-tools.ietf.org/iddiff?url2=draft-ietf-httpbis-digest-headers-12
>
> Internet-Drafts are also available by rsync at rsync.ietf.org:
> :internet-drafts
>
>
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