Hi Stephen, Sean,
Possibly another item worth including in the Security Considerations
section. Suppose MSG1 is sent to a set S1 of users. In the case where MSG2
is sent to only a subset of users in S1, all users from S1 will still be
able to decrypt MSG2 (since MSG2.KEK is computed only from MSG1.CEK). I
don't think you intended for your solution to be used for such dynamic
recipient sets, but it might be worth explicitly mentioning this unfortunate
side-effect of key re-use in any case. (Might be enough to mention that the
recipient lists must be the same for each message.)
Mike J.
-----Original Message-----
From: Internet-Drafts(_at_)ietf(_dot_)org
[mailto:Internet-Drafts(_at_)ietf(_dot_)org]
Sent: Friday, February 09, 2001 7:27 AM
Cc: ietf-smime(_at_)imc(_dot_)org
Subject: I-D ACTION:draft-ietf-smime-rcek-01.txt
A New Internet-Draft is available from the on-line
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This draft is a work item of the S/MIME Mail Security Working
Group of the IETF.
Title : Reuse of CMS Content Encryption Keys
Author(s) : S. Farrell, S. Turner
Filename : draft-ietf-smime-rcek-01.txt
Pages : 7
Date : 08-Feb-01
This note describes a way to include a key identifier in a CMS
enveloped data structure, so that the content encryption key can be
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