Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread HANSEN, TONY L
The ones I wrote certainly didn't require v=1 to come first. ;-)

But you're right: there's probably cause to be concerned.

Tony

On 2/8/18, 10:08 AM, "ietf-dkim on behalf of John R. Levine" 
 wrote:

> "v=1" doesn't have to come first.  It just usually does.  I think there 
was
> a version of RFC4871 that did that, but then when challenged we couldn't
> come up with a good reason to keep it that way.

I wonder how many DKIM libraries will accept a signature where it doesn't.  
  


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Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread Dave Crocker

On 2/8/2018 8:17 AM, Mark Delany wrote:

"v=1" doesn't have to come first.  It just usually does.  I think there was
a version of RFC4871 that did that, but then when challenged we couldn't
come up with a good reason to keep it that way.


Heh. I'm still waiting to hear a good reason as to why "v=" exists at all - 
apart
from exposing brittle parsers which mistakenly expect it to show up as the first
tag.



There appears to be a genetically-encoded belief in the value of version 
numbers, independent of the logic against it.  The belief is pervasive 
and seems to cross all technical cultures, experiential sets, and 
protocol layers.


d/


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Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread Mark Delany
> "v=1" doesn't have to come first.  It just usually does.  I think there was
> a version of RFC4871 that did that, but then when challenged we couldn't
> come up with a good reason to keep it that way.

Heh. I'm still waiting to hear a good reason as to why "v=" exists at all - 
apart
from exposing brittle parsers which mistakenly expect it to show up as the first
tag.

It's about as likely to change as "MIME-Version: 1.0", which is to say, never.


Mark.
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Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread Dave Crocker

On 2/8/2018 8:05 AM, John R. Levine wrote:
I'm not saying any sensible person would do that, but as far as I can 
tell, that's what the spec says.



From a quick review of RFC 5322, I think you are correct.  I also 
believe (know) that this is not what has been intended for header field 
name specification, dating back to RFC 733.


That is, the capability you note is contrary to what I believe was 
intended in the RFC 5322 specification.  And deviation from iontent is 
the requirement for qualifying as an errata on an RFC.


I suggest you submit it.  It will be interesting to see the followup.

d/

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Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread John R. Levine
Header field name rules are in RFC 5322.  That deals with case sensitivity 
for field name strings.  Section 1.2.2 provides the basis for knowing whether 
a defined string is to be parsed in a case sensitive or insensitive manner.


That's right, and all of the fields defined in 5322 have case insensitive 
names, but as far as I can tell, I could define a header like this:


 pickle-header = %d80.111.99.107.108.101 ":" CFWS ( "dill" / "garlic" / 
"kimchee" )

So this is a pickle-header

 Pickle: dill

but this is not:

 pickle: garlic

I'm not saying any sensible person would do that, but as far as I can 
tell, that's what the spec says.


Regards,
John Levine, jo...@iecc.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly
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Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread Dave Crocker

On 2/8/2018 5:22 AM, John R. Levine wrote:
someone asked me about case sensitiveness of the header field name.  I 
looked

for an ABNF in RFC6376, but only found examples and informative notes.


Header field name rules are in RFC 5322.  That deals with case 
sensitivity for field name strings.  Section 1.2.2 provides the basis 
for knowing whether a defined string is to be parsed in a case sensitive 
or insensitive manner.



I was going to say that can't possibly be true, but it's true, there's 
no ABNF for the header.  So, for example, I don't know whether the v= 
field has to come first.  Send an erratum, we'll probably accept it as 
hold for update.


In RFC 6376, note Section 3.2 on tag lists.  The ABNF shows no 
sensitivity to ordering. (The linkage to DKIM-Signature is Section 3.5, 
first paragraph.)



d/
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Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread John R. Levine

"v=1" doesn't have to come first.  It just usually does.  I think there was
a version of RFC4871 that did that, but then when challenged we couldn't
come up with a good reason to keep it that way.


I wonder how many DKIM libraries will accept a signature where it doesn't.

Regards,
John Levine, jo...@iecc.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly
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Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread Murray S. Kucherawy
On Thu, Feb 8, 2018 at 5:22 AM, John R. Levine  wrote:

> someone asked me about case sensitiveness of the header field name.  I
>> looked
>> for an ABNF in RFC6376, but only found examples and informative notes.
>>
>
> I was going to say that can't possibly be true, but it's true, there's no
> ABNF for the header.  So, for example, I don't know whether the v= field
> has to come first.  Send an erratum, we'll probably accept it as hold for
> update.
>

"v=1" doesn't have to come first.  It just usually does.  I think there was
a version of RFC4871 that did that, but then when challenged we couldn't
come up with a good reason to keep it that way.

-MSK
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Re: [ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread John R. Levine

someone asked me about case sensitiveness of the header field name.  I looked
for an ABNF in RFC6376, but only found examples and informative notes.


I was going to say that can't possibly be true, but it's true, there's no 
ABNF for the header.  So, for example, I don't know whether the v= field 
has to come first.  Send an erratum, we'll probably accept it as hold for 
update.


By the way, all field names are case insensitive.  RFC 5322 doesn't say 
that explicitly, but the ABNF for the field names makes it pretty clear, 
On the other hand, RFC 5322 also says that field names can be any printing 
ASCII character so this is be a valid header.


$"%\)': plugh

Regards,
John Levine, jo...@iecc.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly
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[ietf-dkim] Where is the formal definition of DKIM-Signature?

2018-02-08 Thread Alessandro Vesely
Hi,

someone asked me about case sensitiveness of the header field name.  I looked
for an ABNF in RFC6376, but only found examples and informative notes.

Is that an error worth being reported?

Ale
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