Re: [rtcweb] A couple of questions on SDP Identity attribute

Cullen Jennings <fluffy@iii.ca> Thu, 11 October 2018 20:57 UTC

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From: Cullen Jennings <fluffy@iii.ca>
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Date: Thu, 11 Oct 2018 14:57:17 -0600
Cc: RTCWeb IETF <rtcweb@ietf.org>
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To: Christer Holmberg <christer.holmberg@ericsson.com>
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Subject: Re: [rtcweb] A couple of questions on SDP Identity attribute
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> On Oct 11, 2018, at 12:23 AM, Christer Holmberg <christer.holmberg@ericsson.com>; wrote:
> 
> Hi,
>  
> A couple of questions related to some comments on GitHub:
>  
> Q1: In an offer or answer, it allowed to include fingerprints that have NOT been used to assert the identity?

Yes, I think they should because fingerprints can be used even if Identity is not. 

>  
> Q2: If one or more of the fingerprints used to assert the identity change, I assume that the Identity attribute value will always changes a result? Or, is there a chance that different fingerprints would produce the same Identity attribute value?

It will pretty much always changes ( or at least at the same odds of two different things hashing to the same value ) 

If the far end was doing transfers that looked like just changing the SDP in the same offer/answer session to move the media to a new endpoint, the fingerprint and identity values would change but it would also be redoing ICE and setting up a new DTLS session. 

>  
> Regards,
>  
> Christer
>  
>  
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