Re: [IPsec] [Cryptography] Direct public confirmation from Dr. Rogaway (fwd)

[Yoav Nir]

> On 3 Mar 2021, at 21:36, Dan Harkins  wrote:
> 
>  
>   Faster and more secure seem to be compelling reasons. Those reasons are
> probably more compelling for ESP than they are for IKE.

Yes. If we were back in 2008 and figuring out which AEAD we should be using and 
they were both as unencumbered as they are now, maybe we would prefer OCB over 
GCM. 13 years later, every IPsec implementation has AES-GCM, so to add OCB to a 
product, it needs to be significantly better.  I haven’t seen recent numbers, 
but if I remember correctly, the performance difference was in the single-digit 
percentage points. It’s harder to quantify the security differences, but I 
don’t think they were compelling.  However, these arguments apply to a product, 
not necessarily to the protocol.  Adding this as an option for IPsec (and IKE) 
is just fine, whether vendors adopt it or not.

> 
>   The license for OCB always had some caveats like the code could not be used
> for military purposes which is something of a nightmare for a manufacturer of
> general purpose hardware/software. Considering how difficult it would be to
> ensure that your product is never used by a military anywhere in the world,
> that's probably enough of a reason for TLS to not support it. Remember how
> long ECC was delayed for (imagined) IP reasons? 
> 
>   IP is bad news. People don't want anything to do with partially encumbered
> technology. Now this technology is not encumbered at all so, yea, let's do it.
> 
>   If an individual draft was to appear would the WG adopt it as a work item?

Up to the WG, but I would support it.

Yoav

> 
>   regards,
> 
>   Dan.
> 
> On 2/28/21 1:47 PM, Yoav Nir wrote:
>> IIRC the license has allowed OCB to be used for TLS for several years. They 
>> haven’t taken it up. There are no AES-OCB ciphersuites 
>> inhttps://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-4
>>  
>> https://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-4>
>> 
>> So I’m wondering right with you: It has a theoretical advantage in security 
>> and a measurable advantage in speed in software.  Neither were compelling 
>> enough for anyone to bother adding it in TLS ciphersuites.  Why should our 
>> conclusion be any different?
>> 
>> Yoav
>> 
>> 
>>> On 28 Feb 2021, at 22:35, Paul Wouters >> > wrote:
>>> 
>>> 
>>> So now that OCB is finally free, do we want to implement it? :)
>>> 
>>> I'm honestly not sure if the improvements of AES-GCM are worth it.
>>> I haven't heard of vulnerabilities in IKE/ESP wrt. IVs or counters.
>>> 
>>> Paul
>>> 
>>> -- Forwarded message --
>>> Date: Sat, 27 Feb 2021 14:37:30
>>> From: "Salz, Rich via cryptography" >> >
>>> To: "cryptogra...@metzdowd.com " 
>>> mailto:cryptogra...@metzdowd.com>>
>>> Subject: [Cryptography] Direct public confirmation from Dr. Rogaway
>>> 
>>> 
>>> https://mailarchive.ietf.org/arch/msg/cfrg/qLTveWOdTJcLn4HP3ev-vrj05Vg/ 
>>>  :
>>> 
>>>  
>>> 
>>> I can confirm that I have abandoned all OCB patents
>>> 
>>> and placed into the public domain all OCB-related IP of mine.
>>> 
>>> While I have been telling people this for quite some time, I don't
>>> 
>>> think I ever made a proper announcement to the CFRG or on the
>>> 
>>> OCB webpage. Consider that done.
>>> 
>>>  
>>> 
>>> I hope people will use the scheme to do positive things.
>>> 
>>>  
>>> 
>>> phil
>>> 
>>> ___
>>> The cryptography mailing list
>>> cryptogra...@metzdowd.com 
>>> https://www.metzdowd.com/mailman/listinfo/cryptography 
>>> 
>>> ___
>>> IPsec mailing list
>>> IPsec@ietf.org 
>>> https://www.ietf.org/mailman/listinfo/ipsec 
>>> 
>> 
>> 
>> 
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>> 
> 
> -- 
> "The object of life is not to be on the side of the majority, but to
> escape finding oneself in the ranks of the insane." -- Marcus Aurelius
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Re: [IPsec] WGLC for draft-ietf-ipsecme-iptfs

[Christian Hopps]

> On Feb 27, 2021, at 3:14 PM, Michael Richardson  wrote:
> 
> Signed PGP part
> 
> Christian Hopps  wrote:
>>> I still don't really see enough explanation of:
>>> 
>>> 1) what do my probe packets look like?  Can I, for instance, send
>>> regular traffic, padded to the extra size?  That's an optimistic view
>>> of things, but maybe appropriate.  How do I get positive response that
>>> it was accepted?
>>> 
>>> 2) How do I learn about traffic that was dropped?
> 
>> This is what https://tools.ietf.org/html/rfc8899
>>  documents. All that this document
>> should do is provide the on the wire mechanism to send a probe packet
>> and get a reply that it was received, as well as provide for not
>> considering probe loss as loss events for CC (the p-bit). The CC header
>> does this (the sender timestamp is echo'd back for RTT estimates). The
>> implementation of RFC8899 can choose to send user data or not (RFC8899
>> recommends that one should avoid doing this if possible).
> 
> I'll read again, but I am still perceiving a gap between RFC8899 and TFS.
> Perhaps it is obvious to you, having designed and implemented it all over
> three or four years.  In reading it, I didn't understand.
> 
> As I understand it then, I have to send a AGGGRAG_PAYLOAD packet of the new
> size I want to test, I include a sender timestamp in TVal, and I look for
> that echoed back in the TEcho to confirm receipt.  That's my PL?

Correct.

> I would know that it failed if I get a sender timestamp X (getting X+1),
> that the oversize packet was lost.

Correct.

Thanks,
Chris.

> 
> --
> Michael Richardson. o O ( IPv6 IøT consulting )
>   Sandelman Software Works Inc, Ottawa and Worldwide
> 
> 
> 
> 
> 
> 



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Re: [IPsec] [Cryptography] Direct public confirmation from Dr. Rogaway

[John Mattsson]

Hi Dan^2

The OCB2 attack clearly states that ”Our attacks do not apply to OCB1 and 
OCB3”. The attack is only applicable to OCB2 because of the particular way it 
combines the XE and XEX modes. The technical details of the OCB2 attack should 
not erode trust in OCB3.

Note that OCB3 was chosen for the final portfolio of the CAESAR completion in 
2019, i.e. after the OCB2 attack was published in 2018 
https://competitions.cr.yp.to/caesar-submissions.html

If needed, I guess CFRG could be asked to confirm that there is still IRTF 
consensus regarding OCB3.

Cheers,
John

From: IPsec  on behalf of Dan Harkins 

Date: Friday, 5 March 2021 at 02:26
To: Dan Brown , "ipsec@ietf.org" 
Subject: Re: [IPsec] [Cryptography] Direct public confirmation from Dr. Rogaway 
(fwd)


On 3/4/21 4:46 PM, Dan Brown wrote:
Sorry for foolishly forgetting about the OCB RFC, which specifies OCB3.

But that OCB3 RFC is from 2014, five-ish years before the OCB2 break.
  It says:

  "The version of OCB defined in this document is a refinement of two
   prior schemes.  The original OCB version was published in 2001 [OCB1]
   and was listed as an optional component in IEEE 802.11i.  A second
   version was published in 2004 [OCB2] and is specified in ISO 19772.
   The scheme described here is called OCB3 in the 2011 paper describing
   the mode [OCB3]; it shall be referred to simply as OCB throughout
   this document.  The only difference between the algorithm of this RFC
   and that of the [OCB3] paper is that the tag length is now encoded
   into the internally formatted nonce.  See [OCB3] for complete
   references, timing information, and a discussion of the differences
   between the algorithms."

So this RFC describes OCB3.


Again, the OCB2 attack severely erodes my trust in OCB3, though maybe I'm an 
outlier. Maybe I'm also forgetting recent CFRG or other effort to regain trust 
in OCB3 relative to OCB2?

And it also says:

  "OCB has received years of in-depth analysis previous to its
   submission to the CFRG and has been under review by the members of
   the CFRG for over a year.  It is the consensus of the CFRG that the
   security mechanisms provided by the OCB AEAD algorithm described in
   this document are suitable for use in providing confidentiality and
   authentication."

  So CFRG has produced a document defining OCB3 and that document
represents the consensus of the CFRG. I'm not sure what else you think
CFRG should be doing but maybe mention it on the CFRG list instead of
IPsec. Also, Phil Rogaway is on the CFRG list but I don't think he's
on this one. If you have trust issues with OCB then maybe bring them
up with him there.

  Dan.




From: Dan Harkins 
Sent: Mar 4, 2021 5:29 PM
To: Dan Brown ; 
ipsec@ietf.org
Subject: Re: [IPsec] [Cryptography] Direct public confirmation from Dr. Rogaway 
(fwd)


  Hi Dan,
On 3/4/21 11:04 AM, Dan Brown wrote:
Deciding whether to use OCB sounds like a job for CFRG!

As I understand it, OCB2 is severely broken: 
https://eprint.iacr.org/2019/311

That said, OCB1 and OCB3 may be just fine, but a broken OCB2 is not a good 
sign.  All the more reason to defer to CFRG, unless you want to play Monty Hall 
problem.


  CFRG already produced RFC 7253. That's really all they can
be expected to do. It's up to individual IETF WGs to define
how to use that cipher mode in their particular protocols.
That's where we come in.

  regards,

  Dan.


Dan

From: IPsec  On Behalf 
Of Dan Harkins
Sent: Wednesday, March 3, 2021 2:37 PM
To: ipsec@ietf.org
Subject: Re: [IPsec] [Cryptography] Direct public confirmation from Dr. Rogaway 
(fwd)


  Faster and more secure seem to be compelling reasons. Those reasons are
probably more compelling for ESP than they are for IKE.

  The license for OCB always had some caveats like the code could not be used
for military purposes which is something of a nightmare for a manufacturer of
general purpose hardware/software. Considering how difficult it would be to
ensure that your product is never used by a military anywhere in the world,
that's probably enough of a reason for TLS to not support it. Remember how
long ECC was delayed for (imagined) IP reasons?

  IP is bad news. People don't want anything to do with partially encumbered
technology. Now this technology is not encumbered at all so, yea, let's do it.

  If an individual draft was to appear would the WG adopt it as a work item?

  regards,

  Dan.
On 2/28/21 1:47 PM, Yoav Nir wrote:
IIRC the license has allowed OCB to be used for TLS for several years. They 
haven’t taken it up.