Re: [hybi] "fresh" and "uniformly at random":

Adam Barth <ietf@adambarth.com> Mon, 20 June 2011 07:32 UTC

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From: Adam Barth <ietf@adambarth.com>
Date: Mon, 20 Jun 2011 00:31:40 -0700
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To: Denis Lagno <dilmah@chromium.org>
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Subject: Re: [hybi] "fresh" and "uniformly at random":
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You can sensibly apply the term fresh to 1-bit values if you like.
The important aspect is independence from your previous choices.

Adam


On Mon, Jun 20, 2011 at 12:26 AM, Denis Lagno <dilmah@chromium.org> wrote:
> maybe I miss something but in the text "fresh" is applied to 32-bit values..
>
> On Mon, Jun 20, 2011 at 6:57 AM, Adam Barth <ietf@adambarth.com> wrote:
>> On Sat, Jun 18, 2011 at 12:34 AM, Denis Lagno <dilmah@chromium.org> wrote:
>>> On Sat, Jun 18, 2011 at 10:27 AM, Adam Barth <ietf@adambarth.com> wrote:
>>>> The term "fresh" is a term of art in cryptography.  It means, roughly,
>>>> "not used previously."
>>>
>>> So this implies that client must keep track of already used keys? it
>>> imposes limit on length of connection?
>>> True it or false, It should be explicitly clarified in the text.
>>
>> The normal practice in cryptography is to just use large enough values
>> such that the probably of collision is sufficiently small as to be
>> acceptable.  For example, if you use a 20 byte nonce, the probably of
>> collision is zero for all practical purposes.
>>
>> This stuff is all extremely normal.
>>
>> Adam
>>
>