Re: [TLS] Data volume limits

"Blumenthal, Uri - 0553 - MITLL" <uri@ll.mit.edu> Mon, 28 December 2015 21:17 UTC

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From: "Blumenthal, Uri - 0553 - MITLL" <uri@ll.mit.edu>
To: "Salz, Rich" <rsalz@akamai.com>, Eric Rescorla <ekr@rtfm.com>
Thread-Topic: [TLS] Data volume limits
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Date: Mon, 28 Dec 2015 21:17:04 +0000
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Cc: Florian Weimer <fweimer@redhat.com>, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Data volume limits
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"Cranking the KDF" suffices for providing "subkeys" that are cryptographically intractable, which should address the concern of "too much plaintext under the same key". That's less than what I'd consider a "full re-key". ‎And even then "cranking the KDF" with something newly-random isn't a bad idea at all.

I don't think common crypto expertise would disagree.

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  Original Message  
From: Salz, Rich
Sent: Monday, December 28, 2015 16:09
To: Blumenthal, Uri - 0553 - MITLL; Eric Rescorla
Cc: Florian Weimer; tls@ietf.org
Subject: RE: [TLS] Data volume limits

> When the key is changed, the change procedure should involve new randomness. 
‎
I don't think this is necessary, and I don't think the common crypto expertise agrees with you, either. But I am not a cryptographer, maybe one of the ones on this list can chime in.

"Crank the KDF" suffices.