Subject: [Hipsec] Update: HIP base exchange issues status

From: [email-masked] (Pekka Nikander)
Date: Wed Oct 1 03:54:01 2003

I think we have closed issue #5, extensions, and
issue #10a, IPv4 pseudo header format.  I also
think that we can close #11a, HMAC, since I have
received no comments on that.  #13, sending multiple
I1s in parallel, seems also to be closed.  Discussion
on #15, checking of anynymous HIs, seem to be ceased,
and can be IMHO closed, too.  If you disagree with closing
any of these, please send a note NOW.

I am still waiting for comments on the following issues:

    3. NES
4/12. Adding HMAC to R2
   14. Adding of new state E4, to close the weakness
       when receiving an I2 in established state
   17. Unifying the suites for HIP and ESP SAs.

Consequently, we have only two open issues:

  16. Details for handling of LSIs.

    The discussion on this is going on.

  18. Need example checksums

    This basically needs just text, and can be added to -09.
    Hence, this is not a show stopper for -08.

I will send separate mails on issues #3, #4/12, #14 and #17
to get them closed.

Summary:

    Closed:   1, 2, 5, 6, 7, 8, 9, 10, 10a, 11, 11a, 13, 15
    Proposal: 3, 4/12, 14, 17
    Open:     16, 18

--Pekka Nikander

---

From: [email-masked] (Julien Laganier)
Date: Fri Oct 3 08:05:06 2003

Folks,

It seems that draft-moskowitz-hip indicate an IV length of 64 bits (original 
text at the end of the mail). 

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              IV                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

But while using AES_128_CBC, isn't the IV length 128 bits long?

Perhaps the IV field should be 128 bits long? Or use a variable length field, 
using the HIP_TRANSFORM suite_id to infer it. 

So have either:
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |                              IV                               |
      |                                                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
or
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              IV                               /
      /                                                               /
      /                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               /
      /                        Encrypted data                         /
      /                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

What do you think?

--julien

--------------------------------------------------------------------------------------------------------

Original text
-------------

6.3.12 ENCRYPTED

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             Type              |             Length            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                           Reserved                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              IV                               |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Encrypted data                         /
      /                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type         20
      Length       length in octets, excluding T and L fields
      Reserved     zero when sent, ignored when received
      IV           Initialization vector, if needed, zero otherwise
      Encrypted    the data is encrypted using an encryption algorithm as
      data         defined in HIP transform

---

From: [email-masked] (Pekka Nikander)
Date: Mon Oct 6 01:54:03 2003

> text at the end of the mail). 

So it does.

> But while using AES_128_CBC, isn't the IV length 128 bits long?

I have to confess that I don't know.

> using the HIP_TRANSFORM suite_id to infer it. 

Using a variable length field, the length being inferred from
the HIP_TRANSFORM suite, sounds OK to me.

Looks good.

> What do you think?

Opinions, others?  Petri, I think you did the original ENCRYPTED
format used in the current draft.  Do you remember the rationale
back then?

--Pekka Nikander

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From: [email-masked] (Andrew McGregor)
Date: Mon Oct 6 05:41:01 2003

-----BEGIN PGP SIGNED MESSAGE-----

- --On Monday, October 06, 2003 09:22:11 AM +0300 Pekka Nikander 
<[email-masked]> wrote:

> Julien Laganier wrote:
>
>> It seems that draft-moskowitz-hip indicate an IV length of 64 bits
>> (original  text at the end of the mail).
>
> So it does.
>

In CBC modes, the IV is always one cipher block, therefore it is 128 bits 
for AES-CBC (with any key length).

>
>> Perhaps the IV field should be 128 bits long? Or use a variable length
>> field,  using the HIP_TRANSFORM suite_id to infer it.
>

This is the right thing, since cipher blocks and IVs are not required to be 
any particular size, but will always be uniquely determined by the selected 
suite (if not, we didn't specify the suite well enough).

> format used in the current draft.  Do you remember the rationale

I vaguely recall an older draft actually stating that the IV field was 
intended to be the correct size for the cipher (it can hardly be anything 
else, after all).

Andrew

- --------
Andrew McGregor
Director, Scientific Advisor
IndraNet Technologies Ltd
http://www.indranet.co.nz/
Office: +64 3 3656485
Mobile: +64 21 898856

---

From: [email-masked] (Pekka Nikander)
Date: Mon Oct 6 06:23:00 2003

> suite (if not, we didn't specify the suite well enough).
...

> intended to be the correct size for the cipher (it can hardly be anything 

I changed the text to make the IV a variable length field,
and non-existing if the encryption algorithm does not need
an IV.

Issue closed.

--Pekka Nikander