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Re: [TLS] HKDF

Watson Ladd <watsonbladd@gmail.com> Sun, 29 March 2015 18:55 UTC

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Date: Sun, 29 Mar 2015 11:55:42 -0700
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From: Watson Ladd <watsonbladd@gmail.com>
To: Michael StJohns <msj@nthpermutation.com>
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Subject: Re: [TLS] HKDF
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On Thu, Mar 26, 2015 at 7:55 AM, Michael StJohns <msj@nthpermutation.com> wrote:
> On 3/26/2015 3:24 AM, Ilari Liusvaara wrote:
>>
>> Turns out you can't even implement TLS fully in design that does not
>> know about TLS,
>
>
> This is true for TLS1.2 and before, mainly because of the master secret
> expansion and the PRF.  Everything else is bog standard crypto.
>
>> nor does it seem one can even change TLS so that
>> would be possible (at least without introducing gaping security holes).
>
>
> I don't know that I believe that.  TLS is a protocol wrapped around a set of
> cryptographic constructs.  There are ways to use standard constructs in TLS
> to build a secure protocol.   It will require some surgery on TLS1.2, but I
> think that's well underway.

It depends on what the guaranties of the crypto module are. If you
provide AES-GCM, then you need a mechanism to ensure nonces aren't
repeated, and that won't be generic.

Sincerely,
Watson Ladd

>
> Mike
>
>
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