Re: [Emu] Re-charter text

["Dr. Pala" <[e-mail]>]

Hi Mohit,

On 10/24/19 3:30 AM, Mohit Sethi M wrote:
>
> Dear Dr. Pala,
>
> [ ... ]

I replied privately to the first part of this e-mail - I apologize if my 
e-mail did offend you or was in any way inappropriate. To clarify, my 
questions were in reply to Mohit's comments to my previous e-mail on the 
topic [*]. This said, I would like to stay on topic and focus on the 
technical contents. In particular:

> - I think the current text is broad enough to support renewing of 
> credentials. Revoking of credentials has always existed in EAP/AAA 
> architecture. But please note that this does not imply a working group 
> consensus on what you are suggesting. Credential management can 
> involve many more things and not just renewing/revocation. Therefore, 
> I had suggested that we are more "prudent", i.e. "careful", in our 
> choice of words.
>
I understand - thanks for clarifying the point. My question was about 
understanding if the renewal operation was something supported by the 
charter. This was my initial interpretation too, but I just asked in 
response of your comment about being "prudent".

> - EAP is not run in isolation and often may take into account 
> information from various layers above or below. For example, EAP 
> implementations can check whether the SSID/BSSID that the peer is 
> connecting through is correct. While some may call this stack 
> violation, other security folks call this channel binding. I can 
> certainly see that some applications may want to bind the application 
> authentication with the underlying EAP authentication. In fact, in 5G, 
> MSK and EMSK exported from EAP-AKA` is used for a variety of other 
> purposes (such as AKMA and GBA).
>
> [ ... ]
>
That is true - I did not think about these use cases. Indeed, EAP can be 
used (especially in 3gpp/mobile networks) to leverage the USIM 
credentials for, for example, N3IWF/W-AGF for non-3GPP access. However, 
usually, also in that model is still the Core (i.e., your "home" 
network) that handles the credentials, which might not be the same as 
the access network (i.e., roaming) - which is more similar to my 
use-case. The one I was referring to is the situation where the Access 
Network validates your credentials that were issued somewhere else and 
now it wants to renew your credentials with something else: this is 
where it gets tricky about deciding who is the authoritative source of 
the credentials.

Anyhow, thanks for clarifying the interpretation of the charter.

Cheers,
Max

[*] = I think it is unfair to call me "unprofessional" and "erratic" in 
a public forum - I contacted the chair(s) separately to clarify the 
situation.

> On 10/24/19 3:11 AM, Dr. Pala wrote:
>>
>> Hi Mohit, all,
>>
>> I have a question for you - in which sense you mean "prudent" ?
>>
>> Are you saying that creating "general-use" credentials or 
>> provisioning credentials is different ? Creating "general-use" 
>> credentials instead of provisioning/managing the Access Network 
>> credentials seems way more scary and generic than the text I proposed 
>> (which limits the scope of the credentials you should manage with EAP 
>> to the credentials that are used to access the network), therefore, 
>> because of your comment, I would like to have some clarifications 
>> here because my interpretation could be different than yours... and, 
>> based on that, my "happiness" level can be different than initially 
>> reported :D
>>
>> In particular, I would like to understand if the following operations 
>> can be supported by an EAP method:
>>
>>   * Renewing Existing credentials (i.e., maybe credentials that were
>>     generated via the EAP method in the first place)
>>   * Removing Existing credentials (i.e., the network will not use
>>     that credential anymore, therefore it tasks the device to remove
>>     them)
>>
>> Personally, for the work we are doing in different types of Access 
>> Networks (3gpp, CBRS-A, WiFi / WFA, and DOCSIS(r)), I think that the 
>> advantage of the EAP method is about managing the credentials that 
>> are also consumed by the EAP framework - I would not let my 
>> application-layer credentials be managed by the Access Network... and 
>> the opposite should apply as well, IMHO.
>>
>> /*As long as both views are supported, I am ok with the text. */
>>
>> However, if your interpretation of the charter would not allow 
>> operations like registering an existing long-term credential to 
>> access the network (e.g., the device cannot generate/use a different 
>> one), renewing the credentials used to access the network, or 
>> deleting/removing/revoking existing credentials (i.e., no need to 
>> keep a private key or secrets around if it is not useful), then I 
>> would not be happy with the text.
>>
>> Can you please provide clarifications on the above points ?
>>
>> Also, you mention that there is an IESG meeting on October 31st - is 
>> it possible to participate to that meeting ? If so, can you please 
>> let us know the meetings' details... ?
>>
>> Last but not least - I sent you the request earlier for a slot at 
>> IETF 106 for EAP-CREDS and I would like to confirm again with you we 
>> have the slot (I do not recall seeing your reply to that message).
>>
>> Cheers,
>> Max
>>
>>
>> On 10/15/19 2:07 AM, Mohit Sethi M wrote:
>>>
>>> Dear Dr. Pala,
>>>
>>> I think we need to be more prudent when using terms such as 
>>> "credential provisioning" and "credential management". The bullet 
>>> later on in the current charter text specifically says that the 
>>> credentials are for the EAP peer:
>>>
>>>> |Define mechanisms by which EAP methods can support creation of 
>>>> long-term credentials for the peer based on initial limited-use 
>>>> credentials.|
>>> Given that you are happy with the current text, I have a preference 
>>> to leave it in its current form. We are hoping that the IESG will 
>>> discuss this in their telechat on 31 October (which is also the last 
>>> chance before Singapore).
>>>
>>> --Mohit
>>>
>>> On 10/15/19 3:11 AM, Dr. Pala wrote:
>>>>
>>>> Hi Mohit, all,
>>>>
>>>> sorry for the long delay in replying (probably mute at this point), 
>>>> however I think the new text looks great. The only possible change 
>>>> I would provide is the possibility to restrict the scope for the 
>>>> credentials management part. In particular, I would change the 
>>>> following:
>>>>
>>>>     The group will investigate minimal mechanisms with which
>>>>     limited-use EAP authentication credentials can be used for
>>>>     creating general-use long-term credentials.
>>>>
>>>> With something scoped to the credentials for accessing the network 
>>>> itself (instead of a generic credentials provisioning mechanism):
>>>>
>>>>     The group will investigate minimal mechanisms to manage
>>>>     long-term credentials that are use to access the network.
>>>>
>>>> This would probably make the management of credentials scoped to 
>>>> providing and managing the access credentials that the network is 
>>>> authoritative for - I would feel a bit "un-ease" to provide 
>>>> mechanisms to provision credentials to be used outside the access 
>>>> network context (just because it might not be the best enforcement 
>>>> point).
>>>>
>>>> Given that I would be happier with a reduced scope (unless there 
>>>> are good reasons not to limit the scope), I am also happy with the 
>>>> current text (since allows EAP-CREDS to be discussed).
>>>>
>>>> Thanks,
>>>> Max
>>>>
>>>>
>>>> On 9/21/19 6:16 AM, Mohit Sethi M wrote:
>>>>>
>>>>> Hi Georgios,
>>>>>
>>>>> Thanks for reading the charter. I have addressed your comments on 
>>>>> github. Here is the updated text:
>>>>> https://github.com/emu-wg/charter/blob/master/emu-charter.md
>>>>>
>>>>> and here is the diff from the previous version:
>>>>> https://github.com/emu-wg/charter/commit/be1bf557355ecba5d5ee35ab27f3e8fae8c06eef
>>>>>
>>>>> --Mohit
>>>>>
>>>>> On 9/18/19 11:37 AM, Georgios Z. Papadopoulos wrote:
>>>>>> Dear Joe, Mohit and all,
>>>>>>
>>>>>> In overall I find the text well written, while the objectives 
>>>>>> well defined.
>>>>>> Below I have very few comments :
>>>>>>
>>>>>> * TLS is not defined.
>>>>>> * Perfect Forward Secrecy (PFS) is defined twice.
>>>>>> * - An update to enable the use of TLS 1.3 in the context of 
>>>>>> EAP-TLS (RFC 5216). */This document will pdate the security 
>>>>>> considerations relating to EAP-TLS, document the implications of 
>>>>>> using new vs. old TLS versions, add any recently gained new 
>>>>>> knowledge on vulnerabilities, and discuss the possible 
>>>>>> implications of pervasive surveillance./*
>>>>>>
>>>>>> This last point, maybe could be divided in several sentences, 
>>>>>> since I find it too long and, thus, hard to follow.
>>>>>>
>>>>>> Many thanks for your efforts.
>>>>>>
>>>>>> Best regards,
>>>>>> Georgios
>>>>>>
>>>>>>
>>>>>>> On Sep 11, 2019, at 20:50, Mohit Sethi M 
>>>>>>> <[e-mail] <mailto:[e-mail]>> 
>>>>>>> wrote:
>>>>>>>
>>>>>>> Dear all,
>>>>>>>
>>>>>>> Please send in your comments on the charter text by Wednesday, 
>>>>>>> September 18, 2019.
>>>>>>>
>>>>>>> Joe and Mohit
>>>>>>>
>>>>>>> On 8/21/19 11:13 AM, Mohit Sethi M wrote:
>>>>>>>>
>>>>>>>> Dear all,
>>>>>>>>
>>>>>>>> Thank you for a productive meeting @ IETF 105. We had discussed 
>>>>>>>> the new charter text during the working group session in 
>>>>>>>> Montreal. Please find the same text below. This text builds 
>>>>>>>> upon our current charter. Feel free to suggest changes. RFC 
>>>>>>>> 2418 section 2.2 
>>>>>>>> https://tools.ietf.org/html/rfc2418#section-2.2 says the 
>>>>>>>> following about a working group charter:
>>>>>>>>
>>>>>>>>>     2. Specifies the direction or objectives of the working group and
>>>>>>>>>        describes the approach that will be taken to achieve the goals;
>>>>>>>>
>>>>>>>> Please keep this in mind when suggesting changes. Once the text 
>>>>>>>> is ready, we will send it to the IESG for review.
>>>>>>>>
>>>>>>>> Joe and Mohit
>>>>>>>>
>>>>>>>> ------------------------
>>>>>>>>
>>>>>>>> The Extensible Authentication Protocol (EAP) [RFC 3748] is a 
>>>>>>>> network access authentication framework used, for instance, in 
>>>>>>>> VPN and mobile networks. EAP itself is a simple protocol and 
>>>>>>>> actual authentication happens in EAP methods. Several EAP 
>>>>>>>> methods have been developed at the IETF and support for EAP 
>>>>>>>> exists in a broad set of devices. Previous larger EAP-related 
>>>>>>>> efforts at the IETF included rewriting the base EAP protocol 
>>>>>>>> specification and the development of several standards track 
>>>>>>>> EAP methods.
>>>>>>>>
>>>>>>>> EAP methods are generally based on existing security 
>>>>>>>> technologies such as TLS and SIM cards. Our understanding of 
>>>>>>>> security threats is continuously evolving. This has driven the 
>>>>>>>> evolution of several of these underlying technologies. As an 
>>>>>>>> example, IETF has standardized a new and improved version of 
>>>>>>>> TLS in RFC 8446. The group will therefore provide guidance and 
>>>>>>>> update EAP method specifications where necessary to enable the 
>>>>>>>> use of new versions of these underlying technologies.
>>>>>>>>
>>>>>>>> At the same time, some new use cases for EAP have been 
>>>>>>>> identified. EAP is now more broadly in mobile network 
>>>>>>>> authentication. The group will update existing EAP methods such 
>>>>>>>> as EAP-AKA' to stay in sync with updates to the referenced 3GPP 
>>>>>>>> specifications. RFC 7258 notes that pervasive monitoring is an 
>>>>>>>> attack. Perfect Forward Secrecy (PFS) is an important security 
>>>>>>>> property for modern protocols to thwart pervasive monitoring. 
>>>>>>>> The group will therefore work on an extension to EAP-AKA' for 
>>>>>>>> providing Perfect Forward Secrecy (PFS).
>>>>>>>>
>>>>>>>> Out-of-band (OOB) refers to a separate communication channel 
>>>>>>>> independent of the primary in-band channel over which the 
>>>>>>>> actual network communication takes place. OOB channels are now 
>>>>>>>> used for authentication in a variety of protocols and devices 
>>>>>>>> (draft-ietf-oauth-device-flow-13, WhatsApp Web, etc.). Many 
>>>>>>>> users are accustomed to tapping NFC or scanning QR codes. 
>>>>>>>> However, EAP currently does not have any standard methods that 
>>>>>>>> support authentication based on OOB channels. The group will 
>>>>>>>> therefore work on an EAP method where authentication is based 
>>>>>>>> on an out-of-band channel between the peer and the server.
>>>>>>>>
>>>>>>>> EAP authentication is based on credentials available on the 
>>>>>>>> peer and the server. However, some EAP methods use credentials 
>>>>>>>> that are time or domain limited (such as EAP-POTP), and there 
>>>>>>>> may be a need for creating long term credentials for 
>>>>>>>> re-authenticating the peer in a more general context. The group 
>>>>>>>> will investigate minimal mechanisms with which limited-use EAP 
>>>>>>>> authentication credentials can be used for creating general-use 
>>>>>>>> long-term credentials.
>>>>>>>>
>>>>>>>> In summary, the working group shall produce the following 
>>>>>>>> documents:
>>>>>>>>
>>>>>>>>  - An update to enable the use of TLS 1.3 in the context of 
>>>>>>>> EAP-TLS (RFC 5216). This document will pdate the security 
>>>>>>>> considerations relating to EAP-TLS, document the implications 
>>>>>>>> of using new vs. old TLS versions, add any recently gained new 
>>>>>>>> knowledge on vulnerabilities, and discuss the possible 
>>>>>>>> implications of pervasive surveillance.
>>>>>>>>
>>>>>>>>  - Several EAP methods such EAP-TTLS and EAP-FAST use an outer 
>>>>>>>> TLS tunnel. Provide guidance or update the relevant 
>>>>>>>> specifications explaining how those EAP methods 
>>>>>>>> (PEAP/TTLS/TEAP) will work with TLS 1.3. This will also involve 
>>>>>>>> maintenance work based on erratas found in published 
>>>>>>>> specifications (such as EAP-TEAP).
>>>>>>>>
>>>>>>>> - Define session identifiers for fast re-authentication for 
>>>>>>>> EAP-SIM, EAP-AKA, and EAP-AKA’. The lack of this definition is 
>>>>>>>> a recently discovered bug in the original RFCs.
>>>>>>>>
>>>>>>>> - Update the EAP-AKA' specification (RFC 5448) to ensure that 
>>>>>>>> its capability to provide a cryptographic binding to network 
>>>>>>>> context stays in sync with updates to the referenced 3GPP 
>>>>>>>> specifications. The document will also contain any recently 
>>>>>>>> gained new knowledge on vulnerabilities or the possible 
>>>>>>>> implications of pervasive surveillance.
>>>>>>>>
>>>>>>>> - Develop an extension to EAP-AKA' such that Perfect Forward 
>>>>>>>> Secrecy can be provided. There may also be privacy improvements 
>>>>>>>> that have become feasible with the  introduction of recent 
>>>>>>>> identity privacy improvements in 3GPP networks.
>>>>>>>>
>>>>>>>> - Gather experience regarding the use of large certificates and 
>>>>>>>> long certificate chains in the context of EAP-TLS (all 
>>>>>>>> versions), as some implementations and access networks may 
>>>>>>>> limit the number of EAP packet exchanges that can be handled. 
>>>>>>>> Document operational recommendations or other mitigation 
>>>>>>>> strategies to avoid issues.
>>>>>>>>
>>>>>>>> - Define a standard EAP method for mutual authentication 
>>>>>>>> between a peer and a server that is based on an out-of-band 
>>>>>>>> channel. The method itself shall be independent of the 
>>>>>>>> underlying OOB channel and shall support a variety of OOB 
>>>>>>>> channels such as NFC, dynamically generated QR codes, audio, 
>>>>>>>> and visible light.
>>>>>>>>
>>>>>>>> - Define mechanisms by which EAP methods can support creation 
>>>>>>>> of long-term credentials for the peer based on initial 
>>>>>>>> limited-use credentials.
>>>>>>>>
>>>>>>>> The working group is expected to stay in close collaboration 
>>>>>>>> with the EAP deployment community, the TLS working group (for 
>>>>>>>> EAP-TLS work), and the 3GPP security architecture group (for 
>>>>>>>> EAP-AKA' work)
>>>>>>>>
>>>>>>>> ------------------------
>>>>>>>>
>>>>>>>>
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>>>>>>
>>>>>>
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>>>>>
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>>>> -- 
>>>> Best Regards,
>>>> Massimiliano Pala, Ph.D.
>>>> OpenCA Labs Director
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>>>>
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>> -- 
>> Best Regards,
>> Massimiliano Pala, Ph.D.
>> OpenCA Labs Director
>> OpenCA Logo
>>
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-- 
Best Regards,
Massimiliano Pala, Ph.D.
OpenCA Labs Director
OpenCA Logo