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 <ipsec-boun...@ietf.org> on behalf of Dan Harkins <dhark...@lounge.org> Date: Friday, 5 March 2021 at 02:26 To: Dan Brown <danibr...@blackberry.com>, "ipsec@ietf.org" <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 <dhark...@lounge.org><mailto:dhark...@lounge.org> Sent: Mar 4, 2021 5:29 PM To: Dan Brown <danibr...@blackberry.com><mailto:danibr...@blackberry.com>; ipsec@ietf.org<mailto: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<https://urldefense.proofpoint.com/v2/url?u=https-3A__eprint.iacr.org_2019_311&d=DwMDaQ&c=yzoHOc_ZK-sxl-kfGNSEvlJYanssXN3q-lhj0sp26wE&r=mf6j6fOClApRsArWE9wqI1rEGUVkfxZ0aXWmn35nK_c&m=8aGCbnoSU7ozJ-QSzxHGokOgKsea7IZq6669KyaMNNA&s=bSN3q8CM03xYZRbPi2KanYD7GKxGF2HjAZ9AjTc5Nvk&e=> 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 <ipsec-boun...@ietf.org><mailto:ipsec-boun...@ietf.org> On Behalf Of Dan Harkins Sent: Wednesday, March 3, 2021 2:37 PM To: ipsec@ietf.org<mailto: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. There are no AES-OCB ciphersuites inhttps://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-4<%20> 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 <p...@nohats.ca<mailto:p...@nohats.ca>> 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" <cryptogra...@metzdowd.com<mailto:cryptogra...@metzdowd.com>> To: "cryptogra...@metzdowd.com<mailto:cryptogra...@metzdowd.com>" <cryptogra...@metzdowd.com<mailto:cryptogra...@metzdowd.com>> Subject: [Cryptography] Direct public confirmation from Dr. Rogaway https://mailarchive.ietf.org/arch/msg/cfrg/qLTveWOdTJcLn4HP3ev-vrj05Vg/<https://urldefense.proofpoint.com/v2/url?u=https-3A__mailarchive.ietf.org_arch_msg_cfrg_qLTveWOdTJcLn4HP3ev-2Dvrj05Vg_&d=DwMDaQ&c=yzoHOc_ZK-sxl-kfGNSEvlJYanssXN3q-lhj0sp26wE&r=qkpbVDRj7zlSRVql-UonsW647lYqnsrbXizKI6MgkEw&m=2DcLjYKtazJ6kYTZx5uowgB-qJRp6_C8W0rBOr7ZOUI&s=LZV-8STdDDeui1TmXz2JORn2wTtSrkJa_-l3hZK-AO8&e=> : 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<mailto:cryptogra...@metzdowd.com> https://www.metzdowd.com/mailman/listinfo/cryptography<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.metzdowd.com_mailman_listinfo_cryptography&d=DwMDaQ&c=yzoHOc_ZK-sxl-kfGNSEvlJYanssXN3q-lhj0sp26wE&r=qkpbVDRj7zlSRVql-UonsW647lYqnsrbXizKI6MgkEw&m=2DcLjYKtazJ6kYTZx5uowgB-qJRp6_C8W0rBOr7ZOUI&s=_9IPM1exZqE6F4PLBAvpqDF-bHkBi5JPiUyq3eeyfwo&e=> _______________________________________________ IPsec mailing list IPsec@ietf.org<mailto:IPsec@ietf.org> https://www.ietf.org/mailman/listinfo/ipsec<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.ietf.org_mailman_listinfo_ipsec&d=DwMDaQ&c=yzoHOc_ZK-sxl-kfGNSEvlJYanssXN3q-lhj0sp26wE&r=qkpbVDRj7zlSRVql-UonsW647lYqnsrbXizKI6MgkEw&m=2DcLjYKtazJ6kYTZx5uowgB-qJRp6_C8W0rBOr7ZOUI&s=B4s3eO4jZ5UhqwAPEQu9SxQaSVWKuM4HcC1moozCyBc&e=> _______________________________________________ IPsec mailing list IPsec@ietf.org<mailto:IPsec@ietf.org> https://www.ietf.org/mailman/listinfo/ipsec<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.ietf.org_mailman_listinfo_ipsec&d=DwMDaQ&c=yzoHOc_ZK-sxl-kfGNSEvlJYanssXN3q-lhj0sp26wE&r=qkpbVDRj7zlSRVql-UonsW647lYqnsrbXizKI6MgkEw&m=2DcLjYKtazJ6kYTZx5uowgB-qJRp6_C8W0rBOr7ZOUI&s=B4s3eO4jZ5UhqwAPEQu9SxQaSVWKuM4HcC1moozCyBc&e=> -- "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 ________________________________ This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. 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