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Re: [stir] Proposal for update of erratum #6519 - ppt syntax

Marc Petit-Huguenin <marc@petit-huguenin.org> Wed, 21 April 2021 18:13 UTC

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To: Christer Holmberg <christer.holmberg@ericsson.com>, Roman Shpount <roman@telurix.com>, Russ Housley <housley@vigilsec.com>
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From: Marc Petit-Huguenin <marc@petit-huguenin.org>
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Subject: Re: [stir] Proposal for update of erratum #6519 - ppt syntax
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On 4/21/21 10:53 AM, Christer Holmberg wrote:
> Hi,
> 
> I have not been able to follow the discussion in detail, but is there a reason why we simply can's say:
> 
> ident-type = "ppt" EQUAL token / quoted-string
> 
> ...and then add text saying that the only token characters are allowed?

I believe that exceptions to ABNF should be kept to the minimal necessary.   Few implementers read the ABNF, few implementers read normative text.  That means that only the intersection of these two sets will do the right thing.

That's also why we should not deviate from the norm:  We should have used COMMA in Identity, ident-info-uri should have been a field right after signed-identity-digest (similar to name-addr).

Standards are not driven by the best protocol designers' work, but by the worse implementers' shortcomings.

> 
> Regards,
> 
> Christer
> 
> 
> 
> ________________________________
> From: Roman Shpount <roman@telurix.com>
> Sent: Tuesday, April 20, 2021 5:20 PM
> To: Russ Housley <housley@vigilsec.com>
> Cc: Marc Petit-Huguenin <marc@petit-huguenin.org>; Christer Holmberg <christer.holmberg@ericsson.com>; IETF STIR Mail List <stir@ietf.org>
> Subject: Re: [stir] Proposal for update of erratum #6519
> 
> Hi Russ,
> 
> The complete grammar would be:
> 
>        Identity = "Identity" HCOLON signed-identity-digest SEMI
>            ident-info *( SEMI ident-info-params )
>        signed-identity-digest = 1*(base64url-char / ".")
>        ident-info = "info" EQUAL ident-info-uri
>        ident-info-uri = LAQUOT absoluteURI RAQUOT
>        ident-info-params = ident-info-alg / ident-type /
>            ident-info-extension
>        ident-info-alg = "alg" EQUAL token
>        ident-type =  "ppt" EQUAL ( token / ( LDQUOT token RDQUOT ) )
>        ident-info-extension = generic-param
> 
> base64url-char = ALPHA / DIGIT / "-" / "_"
> 
> In this grammar, SEMI is defined as SEMI = SWS  ";"  SWS. This should take care of the SWS after the token.
> _____________
> Roman Shpount
> 
> 
> On Tue, Apr 20, 2021 at 9:22 AM Russ Housley <housley@vigilsec.com<mailto:housley@vigilsec.com>> wrote:
> 
> 
> On Apr 19, 2021, at 9:57 PM, Roman Shpount <roman@telurix.com<mailto:roman@telurix.com>> wrote:
> 
> ident-type = "ppt" EQUAL ( token / ( LDQUOT token RDQUOT ) )
> 
> Since RDQUOT allows whitespace after the double quote, do we need to allow whitespace after token when there are no quotes?
> 
>      ident-type = "ppt" EQUAL ( ( token SWS ) / ( LDQUOT token RDQUOT ) )
> 
> Russ
> 


-- 
Marc Petit-Huguenin
Email: marc@petit-huguenin.org
Blog: https://marc.petit-huguenin.org
Profile: https://www.linkedin.com/in/petithug

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