Re: [Acme] I-D Action: draft-ietf-acme-email-smime-05.txt
Alexey Melnikov <alexey.melnikov@isode.com> Fri, 01 November 2019 17:15 UTC
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From: Alexey Melnikov <alexey.melnikov@isode.com>
To: "Gerd v. Egidy" <gerd.von.egidy@intra2net.com>, acme@ietf.org
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Date: Fri, 01 Nov 2019 17:14:38 +0000
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Subject: Re: [Acme] I-D Action: draft-ietf-acme-email-smime-05.txt
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Hi Gerd, Thank you very much for your comments and sorry for taking long time to reply to you. On 15/07/2019 14:01, Gerd v. Egidy wrote: > Hi Alexey, > > thanks for continuing your work on the smime draft. > >> 1. Do we need to handle text/html or multipart/alternative in email >> challenge? Simplicity suggests "no". However, for automated >> processing it might be better to use at least multipart/mixed >> with a special MIME type. > hmm. I guess with "automated processing" you mean an acme client on the user > side. > > How would a multipart/mixed with a special MIME type help implementing the > client? > > The client just needs to detect the challenge email and extract <token-part1> > from the Subject:-Header. What other data, that could be in the part with the > special mime type, would help implementing such a client? In many clients automatic processing can be invoked based on receiving a particular media type. Also, if an external application is used to handle challenge, it can be associated with a particular media type of various operating systems. > An ACME CA might want to include multipart/alternative and text/html to > present nicely formatted usage instructions to the user when the ACME client > is not integrated into the MUA. Automated clients should not be confused by > such messages. This is one of my open issues. I would like to make implementations of ACME S/MIME-aware clients as easy as possible. If you have a generic email client, support for HTML is pretty much required. But if you don't have a generic email client, adding support for HTML might be an extra burden. So my question is: does better display of instructions to users outweigh extra complexity of handling of text/html? (I am on the fence on this. I think you are arguing that the answer is "yes"). > The same is true for the challenge response: > > When the user manully copies the response from his ACME client program into > his regular MUA, the MUA may compose a multipart/alternative mail with text/ > html and text/plain or even just text/html. Also some company disclaimers and > so on could be added automatically. > > How about using something like in RFC 7468? > -----BEGIN ACME RESPONSE----- > LoqXcYV8q5ONbJQxbmR7SCTNo3tiAXDfowy > jxAjEuX0.9jg46WB3rR_AHD-EBXdN7cBkH1WOu0tA3M9 > fm21mqTI > -----END ACME RESPONSE----- > > This would allow the ACME server to extract the relevant data from most of > such emails by stripping all html tags and ignoring everything outside the > BEGIN/END block. Having recently added HTML tag stripping in an email server, I think this is a big implementation burden, so I would prefer not to do that. In regards to using something like RFC 7468: I think adding BEGIN/END wrapper would provide some extra help in detecting invalid content, so I will add it to the document. > We also should not force the response email to use a subject of "Re: ACME: > <token-part1>", just "<something>ACME: <token-part1>" because MUAs with non- > english language settings may use something else than "Re:" to denote a reply. I really dislike email clients using localized versions of "Re:", but I think you are right :-). Best Regards, Alexey
- [Acme] I-D Action: draft-ietf-acme-email-smime-05… internet-drafts
- Re: [Acme] I-D Action: draft-ietf-acme-email-smim… A. Schulze
- Re: [Acme] I-D Action: draft-ietf-acme-email-smim… Gerd v. Egidy
- Re: [Acme] I-D Action: draft-ietf-acme-email-smim… Alexey Melnikov