Re: [TLS] HSM-friendly Key Computation

Ilari Liusvaara <ilari.liusvaara@elisanet.fi> Mon, 20 April 2015 06:42 UTC

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Date: Mon, 20 Apr 2015 09:42:43 +0300
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
To: Michael StJohns <msj@nthpermutation.com>
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Subject: Re: [TLS] HSM-friendly Key Computation
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On Sun, Apr 19, 2015 at 02:49:58PM -0400, Michael StJohns wrote:
> 
> What I would love to see for TLS1.3 is NO TLS specific mechanisms being
> added to PKCS11.    That if we still sign the finished message, we use a
> true MAC function.  That if we derive keys, we use a bog standard KDF.  That
> we stomp on every TLS specific twist unless there is a specific security
> need to keep TLS secure.

Not possible. There are features (e.g. extractor and resumption/unique
interaction) that can't be feasibly removed (or even deprecated) and which
need PRF'ing secret keys into public data.

Also, true MAC functions just aren't enough for some places (such as
deriving the various master secrets or unique value).



-Ilari