From nobody Fri Aug 14 03:04:18 2020 Return-Path: X-Original-To: txauth@ietfa.amsl.com Delivered-To: txauth@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 0CAB43A0E74 for ; Fri, 14 Aug 2020 03:04:16 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -2.633 X-Spam-Level: X-Spam-Status: No, score=-2.633 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, KHOP_HELO_FCRDNS=0.212, NICE_REPLY_A=-0.949, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id xjtCy0IgzMzO for ; Fri, 14 Aug 2020 03:04:14 -0700 (PDT) Received: from smtp.smtpout.orange.fr (smtp06.smtpout.orange.fr [80.12.242.128]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id B84373A0E7B for ; Fri, 14 Aug 2020 03:04:13 -0700 (PDT) Received: from [192.168.1.11] ([90.79.51.120]) by mwinf5d41 with ME id FN4A230052bcEcA03N4BHD; Fri, 14 Aug 2020 12:04:11 +0200 X-ME-Helo: [192.168.1.11] X-ME-Auth: ZGVuaXMucGlua2FzQG9yYW5nZS5mcg== X-ME-Date: Fri, 14 Aug 2020 12:04:11 +0200 X-ME-IP: 90.79.51.120 To: nadalin@prodigy.net, txauth@ietf.org References: <018901d6719f$22593a20$670bae60$@prodigy.net> From: Denis Message-ID: <9db6ee29-9e43-5893-6779-e5f863418890@free.fr> Date: Fri, 14 Aug 2020 12:04:10 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <018901d6719f$22593a20$670bae60$@prodigy.net> Content-Type: multipart/alternative; boundary="------------3DCE92B4E57F8FF9B6A71D2A" Content-Language: en-GB Archived-At: Subject: Re: [GNAP] Support of FIDO X-BeenThere: txauth@ietf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 14 Aug 2020 10:04:16 -0000 This is a multi-part message in MIME format. --------------3DCE92B4E57F8FF9B6A71D2A Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Hi Tony, > > Dennis, not all the way correct > > * It is also possible to get rid of IDs and passwords using FIDO. > FIDO discloses no private information at all about the user > and no trust relationships need to be defined since there is no AS > > Depends on if you only consider “private information” PII, there can > be all sorts of information passed in ClientData field of the FIDO > response, not desirable but perfectly OK > > * None of these two semantics fit with the FIDO use case where the > subject value is scoped to be locally unique in the context of one > RS. > Hence, the linkage of users between two RSs (or between one RS and > any other server) becomes impossible > > There is nothing that prohibits the RS from sharing registration > information between RS > I am speaking of FIDO U2F where there are two main phases: registration and authentication. The U2F device gives the public key and a Key Handle to the origin online service or website during the user registration step. Later, when the user performs an authentication, the origin online service or website sends the Key Handle back to the U2F device via the browser. The U2F device uses the Key Handle to identify the user's private key, and creates a signature which is sent back to the origin to verify the presence of the U2F device. Thus, the Key Handle is simply an identifier of a particular key on the U2F device. There is no other registration information needed. Sharing such an information between RSs does not allow to link user accounts. Denis > *From:* TXAuth *On Behalf Of *Denis > *Sent:* Thursday, August 13, 2020 10:31 AM > *To:* txauth@ietf.org > *Subject:* [GNAP] Support of FIDO > > This topic has already been tackled on the list, but I open a new > thread for it. > > In OAuth 2.0, one of the goals was to get rid of IDs and passwords. > Since the solution in OAuth 2.0 was to use access tokens, > there have been used everywhere, even when they were not strictly needed. > > It is also possible to get rid of IDs and passwords using FIDO. FIDO > discloses no private information at all about the user > and no trust relationships need to be defined since there is no AS. > > FIDO should be one allowed possibility for the user authentication. In > the case of FIDO, the user is authenticated under a pseudonym > specific to the RS. It may observed that there is no equivalent in > OAuth because of the two different semantics of the subject claim. > > RFC 7519 states: > > The "sub" (subject) claim identifies the principal that is the > subject of the JWT.  The claims in a JWT are normally statements > about the subject. > The subject value MUST either be scoped to be locally unique in > the context of the issuer or be globally unique. > > In one case, it is possible to link the subject claim of two users > between two RSs (i.e. using a locally unique identifier in the context > of the issuer) > while in the other case (i.e. using a globally unique identifier) it > is possible, in addition, to link the subject claim between one RS and > any other server > (i.e. not supporting OAuth) that is using the same globally unique > identifier. > > None of these two semantics fit with the FIDO use case where the > subject value is scoped to be locally unique in the context of one RS. > > Hence, the linkage of users between two RSs (or between one RS and any > other server) becomes impossible. > > There are cases where a user would like to enjoy the unlinkeability > properties of FIDO which cannot be met using the claims currently > defined in OAuth. > > Denis > --------------3DCE92B4E57F8FF9B6A71D2A Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit
Hi Tony,

Dennis, not all the way correct

 

  • It is also possible to get rid of IDs and passwords using FIDO. FIDO discloses no private information at all about the user
    and no trust relationships need to be defined since there is no AS

Depends on if you only consider “private information” PII, there can be all sorts of information passed in ClientData field of the FIDO response, not desirable but perfectly OK

 

  • None of these two semantics fit with the FIDO use case where the subject value is scoped to be locally unique in the context of one RS.
    Hence, the linkage of users between two RSs (or between one RS and any other server) becomes impossible

 

There is nothing that prohibits the RS from sharing registration information between RS

I am speaking of FIDO U2F where there are two main phases: registration and authentication.

The U2F device gives the public key and a Key Handle to the origin online service or website during the user registration step.
Later, when the user performs an authentication, the origin online service or website sends the Key Handle back to the U2F device
via the browser. The U2F device uses the Key Handle to identify the user's private key, and creates a signature which is sent back
to the origin to verify the presence of the U2F device. Thus, the Key Handle is simply an identifier of a particular key on the U2F device.

There is no other registration information needed. Sharing such an information between RSs does not allow to link user accounts.

Denis

 

From: TXAuth <txauth-bounces@ietf.org> On Behalf Of Denis
Sent: Thursday, August 13, 2020 10:31 AM
To: txauth@ietf.org
Subject: [GNAP] Support of FIDO

 

This topic has already been tackled on the list, but I open a new thread for it.

In OAuth 2.0, one of the goals was to get rid of IDs and passwords. Since the solution in OAuth 2.0 was to use access tokens,
there have been used everywhere, even when they were not strictly needed.

It is also possible to get rid of IDs and passwords using FIDO. FIDO discloses no private information at all about the user
and no trust relationships need to be defined since there is no AS.

FIDO should be one allowed possibility for the user authentication. In the case of FIDO, the user is authenticated under a pseudonym
specific to the RS. It may observed that there is no equivalent in OAuth because of the two different semantics of the subject claim.

RFC 7519 states:

The "sub" (subject) claim identifies the principal that is the subject of the JWT.  The claims in a JWT are normally statements about the subject. 
The subject value MUST either be scoped to be locally unique in the context of the issuer or be globally unique.

In one case, it is possible to link the subject claim of two users between two RSs (i.e. using a locally unique identifier in the context of the issuer)
while in the other case (i.e. using a globally unique identifier) it is possible, in addition, to link the subject claim between one RS and any other server
(i.e. not supporting OAuth) that is using the same globally unique identifier.

None of these two semantics fit with the FIDO use case where the subject value is scoped to be locally unique in the context of one RS.

Hence, the linkage of users between two RSs (or between one RS and any other server) becomes impossible.

There are cases where a user would like to enjoy the unlinkeability properties of FIDO which cannot be met using the claims currently defined in OAuth.

Denis


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