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RE: Comments on x942-05 draft

1999-03-12 02:20:42

You are correct.  The corrent write-up does specify the content-encryption
algorithm OID.  I agree that we should replace the content-encryption
algorithm OID with the key-wrap algorithm OID.


At 01:07 PM 3/10/99 -0800, Burt Kaliski wrote:
Dear Russ --

Thanks for the CMS excerpt.

My question is about the parameters to the X9.42 KDF, specifically the OID
associated with the derived key. The field is defined as follows:

      algorithm is the ASN.1 algorithm OID of the symmetric algorithm with
           this KEK will be used. 

I'm assuming that within CMS, the OID would be id-alg-CMS3DESwrap or

x942-05 is unclear about this, as "symmetric algorithm" might be interpreted
as the OID for RC2 or triple-DES, not the key wrapping mechanism. I think
it's better to identify the key wrapping mechanism, in case there's more
than one with the same underlying symmetric algorithm. One risk, of course,
is that the OID for the key wrapping mechansim might be too generic -- so
there should be some way to include parameters (if any) to the key wrapping
OID as input to the KDF.

-- Burt

From:        Russ Housley[SMTP:housley(_at_)spyrus(_dot_)com]
Sent:        Friday, March 05, 1999 10:05 AM
To:  Burt Kaliski
Cc:  Eric Rescorla; jlinn(_at_)securitydynamics(_dot_)com
Subject:     RE: Comments on x942-05 draft 


Please take a look at CMS for this answer.  The AlgorithmIdentifier used
name Ephemeral-Static Diffie-Hellman has a parameter, and that parameter
specifies the key wrap algorithm.


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