Subject: [MMUSIC] late dtls-id request

From: Martin Thomson <[email-masked]>
Date: Thu, 9 Mar 2017 16:06:57 +1100

Can I request the following change to the dtls-sdp doc:

OLD:
              dtls-id-value = 6*256(dtls-id-char)
NEW:
              dtls-id-value = 6*255(dtls-id-char)

I want to put this in a DTLS extension (see
draft-thomson-avtcore-sdp-uks; it would replace the session id that I
originally used) and a value that tops out at 256 requires a whole
extra length byte.

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From: Christer Holmberg <[email-masked]>
Date: Thu, 9 Mar 2017 06:30:48 +0000

Hi Martin,

I have received the same request off-line, so unless someone objects I am
ok to do the change.

Regards,

Christer

On 09/03/17 07:06, "mmusic on behalf of Martin Thomson"
<[email-masked] on behalf of [email-masked]> wrote:

>_______________________________________________
>mmusic mailing list
>[email-masked]
>https://www.ietf.org/mailman/listinfo/mmusic

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From: Christer Holmberg <[email-masked]>
Date: Thu, 9 Mar 2017 06:57:32 +0000

Hi,

Just some background: the reason we used 256 was because that is what ICE
uses for the password and ufrag, as it is assumed to provide good enough
uniqueness.

But, I assume we can make that assumption also with 255.

Regards,

Chorister

On 09/03/17 08:30, "mmusic on behalf of Christer Holmberg"
<[email-masked] on behalf of [email-masked]>

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From: Martin Thomson <[email-masked]>
Date: Thu, 9 Mar 2017 18:15:07 +1100

> But, I assume we can make that assumption also with 255.

For that, 20 would be plenty.

Note that you only require 32 bits of randomness (which fits in the
minimum of 6 characters), which is not quite enough to provide
global-scale uniqueness.  20 pretty much is going to do that (assuming
6 bits per character, which base64 would allow).

FWIW, I would be happier if you moved the 32 bit requirement to 120
and raised the minimum to 20, but that's a much bigger change.

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From: Christer Holmberg <[email-masked]>
Date: Thu, 9 Mar 2017 12:39:16 +0000

Hi,

>and raised the minimum to 20, but that's a much bigger change.

If people think such change would be useful I personally have no problem
implementing it.

But, I¹d like to hear what Roman & others think.

Regards,

Christer

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From: "Paul E. Jones" <[email-masked]>
Date: Fri, 10 Mar 2017 04:07:37 +0000

Christer,

>If people think such change would be useful I personally have no 

Given there are uniqueness requirements for different applications (one 
I'm proposing is in PERC), more than 32 bits might be better.  We know 
SSRC collisions happen, so more randomness would likely help in many use 
cases.

Paul

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From: Christer Holmberg <[email-masked]>
Date: Fri, 10 Mar 2017 07:43:43 +0000

So, who will create the pull request? :)

Regards,

Christer

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From: "Paul E. Jones" <[email-masked]>
Date: Fri, 10 Mar 2017 19:31:50 +0000

I submitted a PR.

Paul

------ Original Message ------
From: "Christer Holmberg" <[email-masked]>
To: "Paul E. Jones" <[email-masked]>; "Martin Thomson" 
<[email-masked]>
Cc: "[email-masked]" <[email-masked]>
Sent: 3/10/2017 2:43:43 AM
Subject: Re: [MMUSIC] late dtls-id request