Could we start using the IETF tracker to keep track of our conversation on the 
issues on MIME sniffing?

The interaction with a "nosniff" header should be one issue.
The other three big issues that come to mind are

*  "scope" (do what situations does this apply)
 * "opt-in case-by-case" (whether one either sniffs ALWAYS or sniffs NEVER, or 
whether it's more nuanced and based on expectation)
* "normative algorithm vs. invariants for specifications".


I'm willing to write up these issues and the sniffing ones from 
http://tools.ietf.org/html/draft-masinter-mime-web-info , and I hope we can 
capture Pete Resnick's issues as well as Alexey's.

Larry


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of 
Tobias Gondrom
Sent: Sunday, October 02, 2011 2:44 PM
To: [email protected]
Cc: [email protected]
Subject: Re: [websec] I-D Action:draft-ietf-websec-mime-sniff-03.txt
Importance: Low

<hat="individual">
Whether browser will implement it, can't tell. Maybe we can learn more when we 
progress further with the mime-sniff draft.

I don't have a strong opinion on the nosniff header.
Depending on where the mime-sniff debate will lead us, it might be a way to 
mitigate concerns that in certain cases you really SHOULD NOT or MUST NOT 
(RFC2119) sniff. Well and with such a header you could enforce exactly that for 
your sources, without breaking other unknown things/sites - which is the main 
reason for many browser vendors to start do sniffing in the first place.
(in one way nosniff could even be a migration path to less sniffing....)

Best regards, Tobias



On 01/10/11 15:30, Phillip Hallam-Baker wrote:
> On Sat, Oct 1, 2011 at 2:47 AM, Adam Barth<[email protected]>  wrote:
>> On Fri, Sep 30, 2011 at 10:14 PM, "Martin J. Dürst"
>> <[email protected]>  wrote:
>>> On 2011/09/29 11:45, Adam Barth wrote:
>>>> On Wed, Sep 28, 2011 at 5:44 PM, "Martin J. Dürst"
>>>> <[email protected]>    wrote:
>>>>> On 2011/09/29 8:26, Adam Barth wrote:
>>>>>> As I recall, the nosniff directive is pretty controversial.
>>>>> But then, as I recall, the whole business of sniffing is pretty 
>>>>> controversial to start with. Are there differences between the 
>>>>> controversiality of sniffing as such and the controversiality of 
>>>>> the nosniff directive that explain why one is in the draft and the 
>>>>> other is not?
>>>> The reason why one is in and the other isn't is just historical.
>>>> nosniff didn't exist at the time the document was originally written.
>>> Your first answer sounded as if the nosniff directive was too 
>>> controversial to be included in any draft, but your second answer 
>>> seems to suggest that it was left out by (historical) accident, and 
>>> that it might be worth to include it.
>> The essential question isn't whether we should include it in the 
>> draft.  The essential question is whether folks want to implement it.
>> If no one wants to implement it, putting it in the draft is a 
>> negative.  If folks want to implement, then we can deal with the 
>> controversy.
> +1
>
> The controversy seems to be of the 'cut off nose to spite face'
> variety. Sniffing is definitely terrible from a security perspective 
> but people do it. Java and Java Script were terrible as well but 
> people did them and then left the rest of us with a mess that had to 
> be fixed slowly over then next ten years.
>
> Sure this is not something we should have to think about but the fact 
> is that the browsers do it and it is better for the standards to 
> describe what the browsers actually do than what people think they 
> should do.
>
>

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