IETF Logo Mail Archive

[Cfrg] Fwd: Hash-Based Key Derivation

David Wagner <daw@cs.berkeley.edu> Tue, 25 October 2005 19:48 UTC

Received: from localhost.localdomain ([127.0.0.1] helo=megatron.ietf.org) by megatron.ietf.org with esmtp (Exim 4.32) id 1EUUmN-00069a-8i; Tue, 25 Oct 2005 15:48:15 -0400
Received: from odin.ietf.org ([132.151.1.176] helo=ietf.org) by megatron.ietf.org with esmtp (Exim 4.32) id 1EUUmL-000689-4c for cfrg@megatron.ietf.org; Tue, 25 Oct 2005 15:48:13 -0400
Received: from ietf-mx.ietf.org (ietf-mx [132.151.6.1]) by ietf.org (8.9.1a/8.9.1a) with ESMTP id PAA15479 for <cfrg@ietf.org>; Tue, 25 Oct 2005 15:47:57 -0400 (EDT)
Received: from taverner.cs.berkeley.edu ([128.32.168.222]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1EUUzK-0007nO-9H for cfrg@ietf.org; Tue, 25 Oct 2005 16:01:39 -0400
Received: from taverner.CS.Berkeley.EDU (localhost.localdomain [127.0.0.1]) by taverner.CS.Berkeley.EDU (8.13.1/8.13.1) with ESMTP id j9PJm17r018566 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 25 Oct 2005 12:48:01 -0700
Received: (from daw@localhost) by taverner.CS.Berkeley.EDU (8.13.1/8.13.1/Submit) id j9PJm1xj018562; Tue, 25 Oct 2005 12:48:01 -0700
From: David Wagner <daw@cs.berkeley.edu>
Message-Id: <200510251948.j9PJm1xj018562@taverner.CS.Berkeley.EDU>
Subject: [Cfrg] Fwd: Hash-Based Key Derivation
To: cfrg@ietf.org
Date: Tue, 25 Oct 2005 12:48:01 -0700
Secret-Bounce-Tag: 9a029cbee41caf2ca77a77efa3c13981
X-Mailer: ELM [version 2.5 PL6]
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
X-Spam-Score: 0.0 (/)
X-Scan-Signature: 7bac9cb154eb5790ae3b2913587a40de
Content-Transfer-Encoding: 7bit
X-BeenThere: cfrg@ietf.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: David Wagner <daw-usenet@taverner.CS.Berkeley.EDU>
List-Id: Crypto Forum Research Group <cfrg.ietf.org>
List-Unsubscribe: <https://www1.ietf.org/mailman/listinfo/cfrg>, <mailto:cfrg-request@ietf.org?subject=unsubscribe>
List-Post: <mailto:cfrg@ietf.org>
List-Help: <mailto:cfrg-request@ietf.org?subject=help>
List-Subscribe: <https://www1.ietf.org/mailman/listinfo/cfrg>, <mailto:cfrg-request@ietf.org?subject=subscribe>
Sender: cfrg-bounces@ietf.org
Errors-To: cfrg-bounces@ietf.org

Simon Blake-Wilson writes:
>Is there a proof somewhere that pre-hashing then MACing makes a good KDF?

In the random oracle model, it is easy to prove that pre-hashing then
applying a PRF makes a good PRF.  In other words, let
    F'(S,X) = F(H(S),X)
where F is a PRF (when its key-input is uniformly distributed) and H is
a random oracle.  Then F' is a PRF, even when its secret-input S is not
uniformly distributed, so long as S has sufficient min-entropy.  Finally,
the latter is all you need to build a good KDF.

_______________________________________________
Cfrg mailing list
Cfrg@ietf.org
https://www1.ietf.org/mailman/listinfo/cfrg

v2.23.0 | Report a Bug | By Email