Subject: RE: [Isms] SSH / Reusability / etc

From: "Blumenthal, Uri" <[email-masked]>
Date: Mon, 18 Apr 2005 17:37:07 -0400

I want one security model to provide session authentication, keying
(derived from authentication), and session parameters (life-time and
mapping to VACM, possibly other parameters). I'd like to have other
security models that intake those parameters and actually protect the
traffic. A-la IPsec approach.

This decoupling allows interchanging keying mechanisms and data
protection mechnisms independently.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]
On Behalf Of Wes Hardaker
Sent: Sunday, April 17, 2005 1:32 PM
To: Sam Hartman
Cc: [email-masked]
Subject: Re: [Isms] SSH / Reusability / etc

>>>>> On Sun, 17 Apr 2005 15:35:32 -0400, Sam Hartman
<[email-masked]> said:

Sam> Also, note that SASL has its own mechanism for conveying the
Sam> inner identity.  So if you were using SASL you might want to
Sam> decide that you didn't need an identity in the SNMP PDU.

[FYI, this (and the other examples) are exactly why the SBSM running
message has a numeric session identifier rather than a user string in
it...  The user string is pulled from the authentication exchange and
is stored by both sides and referenced via the session identifier.
I'd expect TLS, SSH, or anything else that did the authentication
elsewhere to do something similar (and yes, a USM user name field in
the USM security model parameters could in theory be warped into a
session identifier as well.  I'd argue heavily against that scheme
using the same security model number even if the packet format was
otherwise the same)]

-- 
Wes Hardaker
Sparta, Inc.

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From: "David T. Perkins" <[email-masked]>
Date: Mon, 18 Apr 2005 14:48:22 -0700 (PDT)

HI,

Uri - two is understandable. However, how does that differ from
one security model where the data protection mechanism is
negociated like that which is done in other protocols such
as SSL/TLS?

Regards,
/david t. perkins