Subject: I-D ACTION:draft-ietf-ipsec-ciph-aes-ccm-00.txt

From: [email-masked]
Date: Fri, 24 Jan 2003 07:56:39 -0500

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the IP Security Protocol Working Group of the IETF.

	Title		: Using AES CCM Mode With IPsec ESP
	Author(s)	: R. Housley
	Filename	: draft-ietf-ipsec-ciph-aes-ccm-00.txt
	Pages		: 11
	Date		: 2003-1-23
	
This document describes the use of AES CCM Mode, with an explicit
initialization vector, as an IPsec Encapsulating Security Payload
(ESP) mechanism to provide confidentiality, data origin
authentication, connectionless integrity.

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From: Russ Housley <[email-masked]>
Date: Fri, 24 Jan 2003 14:25:19 -0500

I wrote this lnternet-Draft so that we could explore the ESPv3 support for 
authenticated encryption modes.  CCM is the only unencumbered 
authentication encryption mode that I know about today.  I hear that 
another is under development, but for now, we can work with CCM to 
determine whether ESPv3 really meets its design objectives.

Russ

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From: [email-masked] (David Wagner)
Date: 24 Jan 2003 19:28:25 GMT

Russ Housley  wrote:
>CCM is the only unencumbered 
>authentication encryption mode that I know about today.

Maybe I'm overlooking something obvious, but:
What's wrong with AES-CBC encryption followed by SHA1-HMAC?

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From: Russ Housley <[email-masked]>
Date: Fri, 24 Jan 2003 16:59:58 -0500

David:

Nothing is wrong with AES-CBC encryption followed by SHA1-HMAC.  However, 
this cannot be used to test the new features put in ESPv3 to support 
authenticated encryption modes.  To do that, one needs a mode that uses a 
single key for confidentiality and integrity.

Russ

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From: Henry Spencer <[email-masked]>
Date: Fri, 24 Jan 2003 20:12:57 -0500 (EST)

> single key for confidentiality and integrity.

For just testing, that's easy.  Define the Housley-1 authenticating
cipher, a mysterious black box (as far as ESP is concerned, anyway) which
just happens to call AES-CBC routines using some of its key bits and
SHA1-HMAC routines using the rest. 

                                                          Henry Spencer
                                                       [email-masked]

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From: Russ Housley <[email-masked]>
Date: Sun, 26 Jan 2003 15:03:47 -0500

>SHA1-HMAC routines using the rest.

Or, we could use a real authenticated encryption mode that is being used in 
802.11 systems.  If it turns out that it has nice properties in the IPsec 
ESP space as well, then there can be common hardware for the two 
environments, or at least a common core that is used in both.  This would 
provide economy of scale for both communities.

Russ