eap Mailing List: Re: Issue 322: Key Scope

[Bernard Aboba (bernard_aboba]

Has this issue been addressed in -09, or are more changes needed?


Issue 322: Key Scope
Submitter name: Joe Salowey
Submitter email address: jsalowey [at] cisco.com
Date Submitted: December 1, 2005
Reference:
Document: Keying-08
Comment type: T
Priority: 1
Section: 2.4
Rationale/Explanation of issue:
The key scope section is a little hard to understand.
---
There is a lot of discussion about authenticator architecture which
probably should be pulled into a separate section on authenticator
architecture.
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The key scope recommendations should specify which key it refers to.  I
believe it refers to the AAA-key.
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There could be some more generic text about key scoping that describes
the requirements in the lower layer such as:

- Identify what parameters in the lower layer define the key scope
- In phase 0 communicate lower layer parameters that identify the key
scope between Peer and Authenticator
- If channel bindings are supported then include these parameters in the
channel bindings in phase 1a
- The peer can now use the key scope parameters to determine if it has
correct keys for phase 2 lower layer protocol interactions
 
Requested change:

Move the description of authenticator architecture to its own section
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Include in the key scoping section introduction (2.4) something along
the lines of the following text:

"Since authenticator architectures and deployment scenarios vary the
usable scope of the keys derived by the peer and server and sent to the
authenticator vary.  By defining a key scope a lower layer can take
advantage of key caches in the system to optimize lower layer
interactions.  In order to address key scoping the following needs to be
specified by the lower layer:

- Identify what parameters in the lower layer define the key scope
- In phase 0 communicate lower layer parameters that identify the key
scope between Peer and Authenticator
- If channel bindings are supported then include these parameters in the
channel bindings in phase 1a
- The peer can now use the key scope parameters to determine if it has
correct keys for phase 2 lower layer protocol interactions"

The following sections describe key scoping with respect to the AAA-Key
that is sent to the authenticator for lower layer protection.  It is
possible that a lower layer may define other keys and key uses which
need to have scoping applied.
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Make it clear that remaining parts of sections 2.4.1 and 2.4.2 refer to
the AAA-Key.