Re: [TLS] 回复： A TLS extension transfering service indication information

[Eric Rescorla <[e-mail]>]

On Wed, Mar 30, 2016 at 10:40 PM, Dacheng Zhang <[e-mail]
> wrote:

> Thanks again for your comments. See my reply inline please. ^_^
>
>>
>> I'm not following. If you trust the device, then why do you need any kind
>> of cryptographic
>> authentication on the token.
>>
>> Dacheng：Let assume we trust the device. But the APP use a SNI to indicate
>> the service that the APP intends to access. Because the SNI is static which
>> may not be changed for months, it is easier for attackers who monitor the
>> network to get the SNI and use it to gain benefit. We need a securer
>> solution. As I have mentioned in my previous email, this solution will make
>> such attacks more difficult. By the way, SNI is not designed for this
>> purpose, we need to do some additional work to address this issue, right?
>>
>
> Again, you need a threat model. It sounds like you both do and do not
> trust the client
>
> Dacheng: Threat model will be provided. Actually，we don’t try to protect
> against the compromise of client. Or the scenario where an APP against
> another one on the same device. This solution is used to protect against
> the attackers who are able to monitoring the communication between the
> client and the server
>

I'll await this.



>
>
>> Hmm... I'm not at all sure that TLS should address this problem. However,
>> my review
>> was directed to whether your proposed solution even works on its own
>> terms.
>>
>> Dacheng: That is why we need to raise the discussion here. It would be
>> great if this issue could be considered by TLS WG.
>>
>
> I don't find this to be a very compelling use case and I don't think it's
> really appropriate to
> try to solve it at the TLS layer. If you want to have secure flow
> identification you should
> do it at the IP or TCP layers.
>
> Dacheng:Ok, this requirement is quite strong. We need a solution to
> address this issue if we want to use TLS to secure our APPs deployed on
> hundreds o millions o mobile devices.  Also，China mobile and Huawei are working
> with us on this issue.
>

No, you only need it if you want to use a specific charging model.


Could you please tell me why it is better to address this issue at the IP
> or TCP layer. To the best of my knowledge. There is no space in IPv4
> herders to insert any extensions. There are length limit in TCP options. In
> addition, TCP is implemented in kernel mode. It will cost more if we try to
> address this issue at the TCP or IP layer.
>

I think the architectural reasons here are pretty clear. IP is the common
network transport
layer, not TLS. Also, IPv6 has extension headers.

-Ekr


Look forward to more discussions. ^_^
>
> Cheers
>
> Dacheng
>
>>
>>>>
>>>>
>>>
>>
>