Re: [Ecrit] AD review: draft-ietf-ecrit-additional-data-29

[Alissa Cooper <[e-mail]>]

Hi Randy,

Thanks for your response.

On Jul 9, 2015, at 6:47 PM, Randall Gellens <[e-mail]> wrote:

> At 3:19 PM -0700 7/9/15, Alissa Cooper wrote:
> 
>> Hi Randy,
>> 
>> Thanks for addressing my comments. I have one follow-up below.
> 
> Hi Alissa,
> 
> Thanks very much.  Please see in-line.
> 
>> On Jun 28, 2015, at 6:53 PM, Randall Gellens 
>> <[e-mail]> wrote:
>> 
>>>> 
>>>> Section 4.3.4:
>>>> I'm curious about the kinds of "investigations"
>>>> that PSAPs do and how they have used unique
>>>> device IDs in those investigations -- could you
>>>> explain? At first blush this seems to require
>>>> over-sharing of sensitive data.
>>> 
>>> The most common situation that I'm aware of is
>>> repeated false/accidental calls.  If there is no
>>> callback number or it isn't usable, the PSAP may
>>> need to try and track down the device by
>>> contacting the service providers in the area.  In
>>> the case of handsets without current service,
>>> they may be able to determine who last had
>>> service. 
>> 
>> How does the user make an emergency call without current service?
> 
> It varies by region; for example, in the U.S. and some European 
> countries, telephone companies (cellular and wirelines) are required 
> to provide emergency access (911 or 112) even if the device or 
> landline has no service.  So, old cell phones that haven't had 
> service in years can still be used to dial 911 (or 112), and 
> landlines that have been turned off for non-payment can usually still 
> dial 911.  The situation with landlines is a little different from 
> cell phones, so there can be a completely dead landline that is 
> unable to dial 911.  PSAPs do get lots false calls from old cell 
> phones that parents have given to kids as toys, for example.  Or 
> older kids who think it's funny.

Ok

> 
>>> There could be other situations where
>>> this might be useful (e.g., a disconnected call
>>> where the call taker believes there is a need for
>>> assistance but was not able to obtain a location
>>> or other information).
>> 
>> It would be helpful if the above explanation could be included in the draft.
> 
> I have added this.
> 
>> Given the explanation above, does it really make sense for the 
>> device to be providing this information in addition to the service 
>> provider? That is, the device may have many possible device IDs 
>> that it could include, but it may not know which ones the service 
>> provider collects and correlates to specific users, so it won't 
>> necessarily know which ones to provide. Given that all of these IDs 
>> can be uniquely identifying in different contexts, providing 
>> multiple IDs that won't get used seems like not the best idea. And 
>> if the user is abusing the emergency call system, he won't include 
>> these anyway.
> 
> An attacker won't include the information (or would include fake 
> information), but a legitimate device that is used by someone playing 
> pranks, or kids as a toy, or someone who does need help and is using 
> a device without service and can't provide any other information, 
> would include information, and in these cases, it's better if the 
> device includes it, since it's not clear what the service provider 
> knows or will provide.
> 
>> Are we sure that all of the device types specified actually get 
>> used in this way by PSAPs? E.g., I was curious about whether 
>> service providers track device RFIDs.
> 
> I'm not aware of this being common with consumer devices, but it 
> could happen with specialized devices.

Some text to justify the different identifiers would be good to add to the draft.

> 
>> 
>> I also think, as much as I dislike the subscriber privacy indicator 
>> specified in 4.4.1, it should cover this data element as well, 
>> particularly since this element can be inserted by the service 
>> provider without the user knowing.
> 
> The thing about the subscriber privacy indicator is that it's up to 
> local regulation what elements it covers and what it means.  I don't 
> think we can dictate that.

Well, does it have to be in the owner/subscriber block? I thought that implied that it was only relevant to the owner/subscriber data, but if it could be interpreted more broadly then I’m not sure it makes sense to put it in that block.

Thanks,
Alissa

> 
> -- 
> Randall Gellens
> Opinions are personal;    facts are suspect;    I speak for myself only
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> Whenever you find that you are on the side of the majority,
> it is time to reform.                         --Mark Twain