Yeah, good point about side channels. Let's stick to recommending
randomization!

Shumon.

On Fri, Jun 15, 2018 at 8:01 PM Colm MacCárthaigh <[email protected]> wrote:

>
> I think so too; and I wouldn't be so strict on backwards compatibility
> there.
>
> That behavior is a side-channel that defeats DNS privacy in some cases.
> E.g. I can query a record, watch you send an encrypted query, then query
> the record again, and tell what you queried. Within some probability at
> least.
>
> For that reason, It'd be worth experimenting with an implementation that
> does shuffle the results each time.
>
> On Fri, Jun 15, 2018 at 4:54 PM, Shumon Huque <[email protected]> wrote:
>
>> On Fri, Jun 15, 2018 at 5:55 PM Colm MacCárthaigh <[email protected]>
>> wrote:
>>
>>>
>>> Just a question on this: was the old/classic behavior really
>>> random/shuffled? Or was it that bind would "rotate" through iterations
>>> where the order was the same each time if you think of the rrset list as a
>>> ring, but with a different start and end point within that ring? (That's
>>> what's described here:
>>> https://docstore..mik.ua/orelly/networking_2ndEd/dns/ch10_07.htm
>>> <https://docstore.mik.ua/orelly/networking_2ndEd/dns/ch10_07.htm>)
>>>
>>
>> ISC veterans can confirm, but my recollection is that the earliest
>> implementations were indeed as described above - the response RRset was
>> cycled/rotated, rather than randomized.
>>
>> Shumon.
>>
>>
>
>
> --
> Colm
>
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