Re: [6lo] Adam Roach's Discuss on draft-ietf-6lo-nfc-13: (with DISCUSS and COMMENT)

[Adam Roach <[e-mail]>]

Sorry for the relatively slow response. Comments inline.

On 6/7/19 3:01 AM, 최영환 wrote:
>
>> ----------------------------------------------------------------------
>> DISCUSS:
>> ----------------------------------------------------------------------
>>
>> Thanks to everyone who has worked on this document.
>>
>> I generally agree with Benjamin's discuss points, and in particular
>> agree with his comment that it's kind of hard to figure out how all
>> these pieces work together. I have an additional issue that is
>> somewhat related to some of the points he raised, but which is (I think) not completely covered.
>>
>> I'm really confused about what the purported privacy properties of
>> this protocol are. In section 4.3 (which I *think* talks about
>> globally- routable IP addresses, although this is a bit unclear), the document says:
>>
>>     such an IID SHOULD guarantee a stable IPv6 address
>>     because each data link connection is uniquely identified by the pair
>>     of DSAP and SSAP included in the header of each LLC PDU in NFC
>>
>> (Aside: this "should" is a simple statement of fact, not a described
>> behavior of the protocol, and so the use of RFC-2119-style all-caps is
>> not
>> appropriate.)
> Agreed. I will fix it.
>
>> The presence of "a stable IPv6 address" inherently implies the ability
>> to track devices.
> Agreed. I will change them with "a secured and stable IPv6 address". This is ok?


I don't think this changes the issue. Your response below implies that 
the address is stable only over very short periods of time, and that 
would address my concern. If that's true, then the solution would be to 
add text here that qualifies how long the address is stable (e.g.: 
"...such an IID should guarantee a stable IPv6 address during the course 
of a single connection, because...")


>
>> Then, in section 7, I find the following text:
>>
>>
>>     ...the short address of
>>     NFC link layer (LLC) is not generated as a physically permanent value
>>     but logically generated for each connection.  Thus, every single
>>     touch connection can use a different short address of NFC link with
>>     an extremely short-lived link.
>>
>> This text seems to imply that addressing information is, in general,
>> not stable, which appears to flatly contradict the text in section 4.3.
>>
>> Please clarify, in section 4.3, what the duration of stability of
>> these identifiers is.
> This texts means "NFC applications use short-lived connections, and the every connection is made with different address."
> Just one permanent address is not used for a NFC device. If it looks like the texts appears to flatly contract the texts in section 4.3, I need to rephrase the texts for clarification. Thanks. It's good point, I think.