Subject: [eap] Key Naming

From: "Hannes Tschofenig" <[email-masked]>
Date: Wed, 10 Nov 2004 15:28:51 +0100

hi all,

i took a look at the most recent version of the keying framework document 
[3]. i had to notice that an important concept of the document is not 
clearly described.

this term has caused a lot of confusion in the past.

i got the impression that people use it for three

purposes. :

a) include the identities of the participating entities in the key 
derivation function

some text snippets in the current eap keying framework draft [3] give the 
impression that the concept of key naming refers to this issue.

b) include the identities of the participating entities in the messages

this aspect is mentioned in [1] and recently came up in the context of 
mikey.

c) information used to select a security association

with regard to (c) two issues arise:

1) how do you select the correct security association (and consequently the 
correct key) for an outbound message (could be data traffic or signaling 
traffic)?

this aspect is interesting in the context of mobility, several concurrent 
sessions, rekeying etc.

2) how do you select the correct security association for an inbound 
message.

rfc 2401 does not directly differentiate inbound and outbound processing:

rfc 2401, section says:

"
   A security association is uniquely identified by a

triple consisting
   of a Security Parameter Index (SPI), an IP

Destination Address, and a
   security protocol (AH or ESP) identifier.
"

this definition obviously only helps for the inbound

direction but obviously not for the outbound

direction.

this raises a few questions:

- what is meant by key naming?

- why was it necessary to introduce a new term?

- can we change the terminology or should we

define/reuse/change a term?

i would therefore suggest to provide a clarification and to change the 
terminology of the concept "key naming". if the concept of (c) has to be 
used then i would rather change it to something like "key index" or to talk 
about the unique selection of a security association.

ciao
hannes

[1] M. Abadi and R. Needham: "Prudent engineering

practice for cryptographic protocols", IEEE

Transactions on Software Engineering, 22(1):6--15,

1996.

[2] H. Tschofenig: "[Pana] EAP keying issues and

PANA", 27 Dec 2003, available at PANA mailing list at

http://www1.ietf.org/mail-archive/web/pana/current/ms

g00299.html.

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