Subject: Comments on draft-melnikov-rfc2831bis-01

From: Simon Josefsson <[email-masked]>
Date: Wed, 09 Oct 2002 03:02:25 +0200

The draft does not describe how the sequence numbers are used in
integrity/confidentiality protection, here is some proposed text.

In section 2.3, add the following to the sentence beginning with
"where MD5 is as":

   The sequence number is an unsigned counter set to 0 after initial
   or subsequent authentication and incremented with 1 after each
   successfully generated or verified MAC, wrapping around to 0 when
   exceeding its 4-byte

In section 2.4, add the following to the sentence beginning with
"The MAC block is":

   The sequence number is an unsigned counter set to 0 after initial
   or subsequent authentication and incremented with 1 after each
   successfully generated or verified SEAL, wrapping around to 0 when
   exceeding its 4-byte size.

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From: Alexey Melnikov <[email-masked]>
Date: Wed, 09 Oct 2002 08:09:50 -0600

>    successfully generated or verified MAC, wrapping around to 0 when

Actually the current text says:

The sequence number is initialized to zero, and  incremented by one for
each message sent.

I will change it to:

The sequence number is an unsigned number initialized to zero after
initial or subsequent authentication, and incremented by one for each
message sent/successfully verified. (Note, that there are two independent
counters for sending and receiving.) The sequence number wraps around to
0 after 2**32-1.

I've also added

The receiver's sequence counter is incremented if they match.

at the end of the next paragraph starting with "Upon receipt ...".

Any comments?

>    exceeding its 4-byte size.

Same changes as above.

Regards,
Alexey Melnikov
__________________________________________
R & D, ACI Worldwide/MessagingDirect
Watford, UK

Work Phone: +44 1923 81 2877
Home Page: http://orthanc.ab.ca/mel

I speak for myself only, not for my employer.
__________________________________________

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From: Simon Josefsson <[email-masked]>
Date: Thu, 10 Oct 2002 02:14:55 +0200

> at the end of the next paragraph starting with "Upon receipt ...".

Looks good, thanks.  The main unclear point I was thinking of was if
the sequence number was reset to 0 after subsequence authentication or
not.

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From: Alexey Melnikov <[email-masked]>
Date: Wed, 09 Oct 2002 08:09:50 -0600

I will change it to:

I've also added

Any comments?

Same changes as above.

Regards,
Alexey Melnikov

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From: Simon Josefsson <[email-masked]>
Date: Thu, 10 Oct 2002 02:14:55 +0200