On Mar 13, 2008, at 7:08 PM, Paul Kyzivat wrote:

>
>
> Dean Willis wrote:
>
>> How about:
>>      From: +12142821376 <sip:[EMAIL PROTECTED]>
>
> Are we now assuming that 4474 vouches for the correctness of the  
> display name?

  No, we're not. We're assuming that since we can't verify the  
contents of the display name, that having such information signed by  
RFC 4474 would be a Bad Thing.

In other words, we are trying to limit the content of the RFC-4474  
signed fields to include only things that the authentication service  
can verify. It should not sign and assert as true that which it cannot  
verify. So when we have a call from the PSTN, the Identity header MUST  
NOT assert anything about the PSTN-provided information.

But here's the problem with Adam's idea.:

> Various exceptions to such policies might arise for cases like  
> anonymity; if the AoR asserted in the From field uses a form like 'sip:[EMAIL 
> PROTECTED]' 
> , then the 'example.com' proxy should authenticate that the user is  
> a valid user in the domain and insert the signature over the From  
> header field as usual. Note that this check is performed on the addr- 
> spec in the From header field (e.g., the URI of the sender, like 'sip:[EMAIL 
> PROTECTED]') 
> ; it does not convert the display- name portion of the From header  
> field (e.g., 'Alice Atlanta'). Authentication services MAY check and  
> validate the display-name as well, and compare it to a list of  
> acceptable display-names that may be used by the sender; if the  
> display-name does not meet policy constraints, the authentication  
> service MUST return a 403 response code.

If I'm reading it correctly, that gives us some flexibility with the  
display-name.

> In any case, callerid includes name as well as number, so we  
> probably need to reserve the display name for carrying the calling  
> name, not the calling number.

Interesting question. I think the phone number is part of the display  
name:

From: Dean Willis +12142821376 <sip:[EMAIL PROTECTED]>

--
Dean
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