Re: [GNAP] [Txauth] Three Client-Server use cases with several ASs built along "Privacy by Design" (PbD)

Francis Pouatcha <fpo@adorsys.de> Tue, 11 August 2020 22:40 UTC

Return-Path: <fpo@adorsys.de>
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 027DF3A0D66 for <txauth@ietfa.amsl.com>; Tue, 11 Aug 2020 15:40:21 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.098
X-Spam-Level:
X-Spam-Status: No, score=-2.098 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=adorsys.de
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 ky6UHzEgu8Kh for <txauth@ietfa.amsl.com>; Tue, 11 Aug 2020 15:40:17 -0700 (PDT)
Received: from mail-wr1-x42f.google.com (mail-wr1-x42f.google.com [IPv6:2a00:1450:4864:20::42f]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id CA1EF3A0B34 for <txauth@ietf.org>; Tue, 11 Aug 2020 15:40:16 -0700 (PDT)
Received: by mail-wr1-x42f.google.com with SMTP id 88so271278wrh.3 for <txauth@ietf.org>; Tue, 11 Aug 2020 15:40:16 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=adorsys.de; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=2sdU3XB5tPxMH/5JexTOzzcgrgz5zLizkLe+RWxSMhA=; b=ckxVXgG1+DVX6Ng+ViYlnlBceov/Aj5AVaW9XWX58oqlXN6RdqdCfXeOBNyqM4+Wui 6/4iHAqcTm+McNHfgSi25YwbtbphEAzsDQd2wlKMNCB2GWKOEYq7+jvfIgFIli4BkOTJ qQJJq/EF77i3LpqqIj5p8k+853A7ML7EDD4AY=
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=2sdU3XB5tPxMH/5JexTOzzcgrgz5zLizkLe+RWxSMhA=; b=RdkAgmCjUvs1+XxfDJJfyQmCLRZnKDNnNV6bZ4HP9G7EeGSzbMP2YEk59N4tnwJl8c R64h5CmqF+WHe//rJTR+x6iTXKS1l9qPe4Akof3oN3FAWjellzKrecKn2CvDv7yjh1Rb l9Ym4A/AEEN6NzaVHcO+PGtmzyRSzewPUsQxvTtpwoZ+8476x+hi0wYvHC/1kE60mTZJ Dk8h8jV94ygW/gLx0ROW9g8A3humNLaYAECNVdtxMtegRrsD8+OAIFpvOdd59ThWcRgO qAH1qSvu3HhepB37dQ2deT3mxQzmIwpBr3x/uGf4G+L6aD32+zP9FWHew1Tt97lA3Tms gPLw==
X-Gm-Message-State: AOAM533dX9ZHJ3TKsGkjin8O6oIKupRGlh5+/4AILT3wgwZ3twV7ntNa Anke0rEWNA6jXIwu3pLY8lcOy35z3N0tZlvYCqmXOg==
X-Google-Smtp-Source: ABdhPJzsJdsjVTXGll5kI14nSsWXXxl+LLGNVq/WpGPBmpb3tMOGZhhycKkEJqIB1o3AIqo0jbyDmeTXug1/Qepj7SI=
X-Received: by 2002:a5d:45c9:: with SMTP id b9mr30359282wrs.283.1597185615129; Tue, 11 Aug 2020 15:40:15 -0700 (PDT)
MIME-Version: 1.0
References: <d2ee5da2-8e88-15c8-8646-087860463d2c@free.fr> <CAOW4vyOwQTMoo2Nmb8KNcVM5hdOW69FzZTK5XQ2fRL9CC8+SUA@mail.gmail.com> <CAM8feuT2K2xpF=VES11kihsqfGK4RCzdSCU=HCLijxLvnc=8LA@mail.gmail.com> <CAOW4vyM0jkw9qTzohzGaNwvvT6JGqcUbdqXnJFq9ahqnRPnuGQ@mail.gmail.com> <CAK2Cwb65cdpoX=B5e4cE6fk2-8fNA_KQhJ-tA2FVZ6mFA2N7-w@mail.gmail.com>
In-Reply-To: <CAK2Cwb65cdpoX=B5e4cE6fk2-8fNA_KQhJ-tA2FVZ6mFA2N7-w@mail.gmail.com>
From: Francis Pouatcha <fpo@adorsys.de>
Date: Tue, 11 Aug 2020 18:40:04 -0400
Message-ID: <CAOW4vyMsuxob5mcqMkPypwg6HsNdCMSW8eHXsWhG7AHG9R+f+g@mail.gmail.com>
To: Tom Jones <thomasclinganjones@gmail.com>
Cc: Fabien Imbault <fabien.imbault@gmail.com>, Denis <denis.ietf@free.fr>, GNAP Mailing List <txauth@ietf.org>
Content-Type: multipart/alternative; boundary="0000000000003b043b05aca1c118"
Archived-At: <https://mailarchive.ietf.org/arch/msg/txauth/IYBuw32n5UCTD3p56WAEhKlyJ3w>
Subject: Re: [GNAP] [Txauth] Three Client-Server use cases with several ASs built along "Privacy by Design" (PbD)
X-BeenThere: txauth@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: <txauth.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/txauth>, <mailto:txauth-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/txauth/>
List-Post: <mailto:txauth@ietf.org>
List-Help: <mailto:txauth-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/txauth>, <mailto:txauth-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 11 Aug 2020 22:40:21 -0000

On Tue, Aug 11, 2020 at 6:27 PM Tom Jones <thomasclinganjones@gmail.com>
wrote:

> "The token request must not mention any reference of the RS."
> this cannot be an absolute rule. I have cases were the client needs to
> tell the user which they are coming back for additional grants.
> The reason is typically because a request by the client for data/access
> from the rs was rejected. The reason for the rejection is important for the
> client to make the case to the user for additional permissions.
> Peace ..tom
>
- If you want privacy, *don't* expose RS identity to AS.
- If you want transparency, expose RS identity to AS.
You can't have both....
/Francis

>
>
>
> On Tue, Aug 11, 2020 at 2:27 PM Francis Pouatcha <fpo=
> 40adorsys.de@dmarc.ietf.org> wrote:
>
>> Hello Fabian,
>>
>> On Tue, Aug 11, 2020 at 2:17 AM Fabien Imbault <fabien.imbault@gmail.com>
>> wrote:
>>
>>> Hi Francis,
>>>
>>> I think Denis points to the fact that, in the current situation, the AS
>>> receives the resource request from the Client and therefore knows what
>>> tokens are asked.
>>>
>> The token request must not mention any reference of the RS.
>>
>>
>>> Then it also implements the consent interface (and possibly the login
>>> too) and so it also knows who validates and what is accepted or not.
>>>
>> Decoupling this does not change the privacy context, as the AS issues the
>> Token. AS needs to add a reference to the RC in the token. SO AS can
>> correlate on StudentId anyway.
>>
>>
>>> I don't think the abstract flow deals with those privacy concerns.
>>>
>> To solve the privacy problem addressed in this thread, we need to go the
>> (SSI/DiD/VC) way. Then UNIV-0 (in his role of RS) will have to issue a VC
>> (Verifiable Credential) to the Student (in his role of RC). The Student
>> will then present this claim to UNIV-1 during his registration. In this
>> case we need no Grant negotiation and no AS.
>>
>> Best regards.
>> /Francis
>>
>>>
>>
>>>
>>> Then I agree with you on the audience field of the token, if left empty
>>> it simplifies part of the problem, although it removes a big part of the
>>> control you may want from directed tokens. That's why I'm willing to better
>>> develop the RS hiding idea.
>>>
>>> Fabien
>>>
>>> Le mar. 11 août 2020 à 05:58, Francis Pouatcha <fpo=
>>> 40adorsys.de@dmarc.ietf.org> a écrit :
>>>
>>>> Hello Denis,
>>>>
>>>> what you describe in the use case seems to be the default behavior of
>>>> the protocol. Let me map it with this abstract protocol flow:
>>>>
>>>> +-----------+      +--------------+  +-----------+  +----+
>>>>  +---------------------+
>>>> | Requestor |      | Orchestrator |  | RS        |  | GS |  | Resource
>>>> Controller |
>>>> | is UNIV-1 |      |  is UNIV-1   |  | is UNIV-0 |  | or |  |
>>>>  is          |
>>>> |   Staff   |      | Registr. App |  | Server    |  | AS |  |
>>>>  Student       |
>>>> +-----------+      +--------------+  +-----------+  +----+
>>>>  +---------------------+
>>>>   |(1) RegisterStudent    |                |           |
>>>> |
>>>>   |---------------------->|                |           |
>>>> |
>>>>   |                       |(2) RequestRecordIntent(RecordType,StudentId,
>>>>   |                       |
>>>>  OrchestratorId):AuthRequest[RecordType,StudentId]
>>>>   |                       |<-------------->|           |
>>>> |
>>>>   |                       |                |           |
>>>> |
>>>>   |                       |(3)
>>>> AuthZRequest(RecordType,StudentId,OrchestratorId)
>>>>   |                       |--------------------------->|
>>>> |
>>>>   |                       |                |           |(4)
>>>> ConsentRequest(RecordType,
>>>>   |                       |                |           |
>>>>  OrchestratorId):Consent
>>>>   |                       |                |
>>>>  |<-------------->|
>>>>   |
>>>>  |(5) AuthZ[RecordType,StudentId,OrchestratorId]
>>>>   |                       |<---------------------------|
>>>> |
>>>>   |                       |                |           |
>>>> |
>>>>   |                       |(2)
>>>> RequestRecord(RecordType,StudentId,OrchestratorId)
>>>>   |                       |     :RecordOf[StudentId]   |
>>>> |
>>>>   |                       |<-------------->|           |
>>>> |
>>>>   |(7) Registered         |                |           |
>>>> |
>>>>   |<----------------------|                |           |
>>>> |
>>>>   +                       +                +           +
>>>> +
>>>>
>>>> we assume the authz request sent by "Client" to "AS" describes the
>>>> protected resource without referring to the authz server. An AS can issue
>>>> the authz to release the graduation record  of a student
>>>> ((5) AuthZ[RecordType,StudentId,OrchestratorId]), without any reference to
>>>> the target university.
>>>>
>>>> What matters for this authz object is:
>>>> - StudentId: a reference to the student as known to the resource server.
>>>> - RecordType: a reference to a resource of type graduation record as
>>>> understandable  by the resource server.
>>>> - OrchestratorId: reference to the Orchestrator. Can be used to bind
>>>> authz to Orchestrator..
>>>>
>>>> But:
>>>> - RS must trust AS issued token.
>>>> - StudentId must be known to RS, AS and Orchestrator.
>>>>
>>>> Therefore, the AS does not need to know the RS. Keep the audience field
>>>> empty.
>>>>
>>>> Same principle applies for the second use case.
>>>>
>>>> What privacy problem do you see here?
>>>>
>>>> Best regards.
>>>> /Francis
>>>>
>>>> On Tue, Aug 4, 2020 at 5:08 AM Denis <denis.ietf@free.fr> wrote:
>>>>
>>>>> I tried my best twice to download three use cases in the Use cases
>>>>> directory, but I failed.
>>>>>
>>>>> Rather than failing a third time, here is the direct link of the
>>>>> second try:
>>>>>
>>>>>
>>>>> https://github.com/ietf-wg-gnap/general/wiki/Three-Client-Server-use-cases-with-several-ASs-built-along-%22Privacy-by-Design%22-(PbD)
>>>>>
>>>>> Denis
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Txauth mailing list
>>>>> Txauth@ietf.org
>>>>> https://www.ietf.org/mailman/listinfo/txauth
>>>>>
>>>>
>>>>
>>>> --
>>>> Francis Pouatcha
>>>> Co-Founder and Technical Lead
>>>> adorsys GmbH & Co. KG
>>>> https://adorsys-platform.de/solutions/
>>>> --
>>>> TXAuth mailing list
>>>> TXAuth@ietf.org
>>>> https://www.ietf.org/mailman/listinfo/txauth
>>>>
>>>
>>
>> --
>> Francis Pouatcha
>> Co-Founder and Technical Lead
>> adorsys GmbH & Co. KG
>> https://adorsys-platform.de/solutions/
>> --
>> TXAuth mailing list
>> TXAuth@ietf.org
>> https://www.ietf.org/mailman/listinfo/txauth
>>
>

-- 
Francis Pouatcha
Co-Founder and Technical Lead
adorsys GmbH & Co. KG
https://adorsys-platform.de/solutions/