Not true John, the CTAP support that is current would support the web-view w/o 
any changes 

-----Original Message-----
From: OAuth [mailto:[email protected]] On Behalf Of John Bradley
Sent: Monday, March 6, 2017 12:16 PM
To: Hannes Tschofenig <[email protected]>
Cc: [email protected]; [email protected]
Subject: Re: [OAUTH-WG] I-D Action: draft-ietf-oauth-native-apps-08.txt

On fido I can tell you that for security reasons U2F wont work from a web-view 
currently.

Once we move to Web Auth (Fido 2) where the OS provides a API for apps to call 
to get the token it will work but the tokens are audianced to the app based on 
its developer key and bundle_id so that a app cant ask for a token for a 
different site to do correlation. 

It is true that Fido UAF currently requires a web-view to work as the 
authenticator is effectively compiled in to each application, and that 
application has access to the private keys on most platforms (Samsung knox 
being the only exception to that that I know of where the keys are managed by a 
common API to hardware key storage, but they are scoped like U2F as well)

So for the most part it is true and that unless you use the browser to get the 
Fido token the audience is for the app.
Example  Salesforce creates native app that may use enterprise SSO via SAML, 
and the enterprise may use Fido as a authentication factor.
If they use the webview + fido API approach the app can only get a token for 
SalesForce based on its signing key.  It could fire up the web-view and do U2F 
authentication with the enterprise after Salesforec has redirected the user.  
However it will give every enterprise a token audience to Salesforce with a 
salesforce specific key.   If there is a second app for say Slack if they do 
the same thing the enterprise would get a slack audienced token and a slack key 
forcing a separate registration. 

The recommended alternative is that the app use a custom tab for the user to 
SalesForce and that redirect to the enterprise.
The enterprise gets the same token/key with the correct audience from all apps 
on the device using the browser or custom tab. 
The user may not need to signin a second time, and if they do there Fido token 
will not need to be re-registerd.

The Fido API approach really only works for first party apps like PayPal if the 
the app is not doing federation and paypal is doing the authentication for 
there own app.

Token binding private keys have similar issues.   The pool of private keys will 
probably not be shared between apps, and not between the app and the browser 
(Win 10 may be an exception but it is not documented yet)

In the case of using AppAuth with token binding the browser maintains the keys 
so the enterprise would be able to see the same key and use the same cookies 
across all AppAuth Apps.

You can include token binding in your app, however the token bindings and 
cookies are going to be sand boxed per app.  
Depending on implementation the app gets access to the cookie, but perhaps not 
to the private token binding key.  (At least I don't think it will in Android 
embedded webview).

We could expand on this later in an update to the BCP once Web Authentication 
and Token Binding are final.

There are still some unknowns, but in general for any sort of SSO/Federation 
3rd party app I don’t see recommending anything other than a custom tab/ view 
controller/ external browser.

William can take the formatting question:)

John B.
> On Mar 6, 2017, at 4:41 PM, Hannes Tschofenig <[email protected]> 
> wrote:
> 
> Hi William, Hi John,
> 
> I just re-read version -8 of the document again.
> 
> Two minor remarks only.
> 
> Editorial issue: Why do you need to introduce a single sub-section 
> within Section 7.1. (namely Section 7.1.1)?
> 
> Background question: You note that embedded user agents have the 
> disadvantage that the app that hosts the embedded user-agent can 
> access the user's full authentication credential. This is certainly 
> true for password-based authentication mechanisms but I wonder whether 
> this is also true for strong authentication techniques, such as those 
> used by FIDO combined with token binding. Have you looked into more 
> modern authentication techniques as well and their security implication?
> 
> Ciao
> Hannes
> 
> On 03/03/2017 07:39 AM, William Denniss wrote:
>> Changes:
>> 
>> – Addresses feedback from the second round of WGLC.
>> – Reordered security consideration sections to better group related topics.
>> – Added complete URI examples to each of the 3 redirect types.
>> – Editorial pass.
>> 
>> 
>> 
>> On Thu, Mar 2, 2017 at 10:27 PM, <[email protected] 
>> <mailto:[email protected]>> wrote:
>> 
>> 
>>    A New Internet-Draft is available from the on-line Internet-Drafts
>>    directories.
>>    This draft is a work item of the Web Authorization Protocol of the IETF.
>> 
>>            Title           : OAuth 2.0 for Native Apps
>>            Authors         : William Denniss
>>                              John Bradley
>>            Filename        : draft-ietf-oauth-native-apps-08.txt
>>            Pages           : 20
>>            Date            : 2017-03-02
>> 
>>    Abstract:
>>       OAuth 2.0 authorization requests from native apps should only be made
>>       through external user-agents, primarily the user's browser.  This
>>       specification details the security and usability reasons why this is
>>       the case, and how native apps and authorization servers can implement
>>       this best practice.
>> 
>> 
>>    The IETF datatracker status page for this draft is:
>>    
>> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-ietf-oauth-native-apps%2F&data=02%7C01%7Ctonynad%40microsoft.com%7Ceff092e6b2894ace8f8408d464cda4d5%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636244281810078497&sdata=YQ0dcSViranVx4sjH7aeFrEYvTgbQM3OruoK%2FR7EZak%3D&reserved=0
>>    
>> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdat
>> atracker.ietf.org%2Fdoc%2Fdraft-ietf-oauth-native-apps%2F&data=02%7C0
>> 1%7Ctonynad%40microsoft.com%7Ceff092e6b2894ace8f8408d464cda4d5%7C72f9
>> 88bf86f141af91ab2d7cd011db47%7C1%7C0%7C636244281810078497&sdata=YQ0dc
>> SViranVx4sjH7aeFrEYvTgbQM3OruoK%2FR7EZak%3D&reserved=0>
>> 
>>    There's also a htmlized version available at:
>>    
>> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftools.ietf.org%2Fhtml%2Fdraft-ietf-oauth-native-apps-08&data=02%7C01%7Ctonynad%40microsoft.com%7Ceff092e6b2894ace8f8408d464cda4d5%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636244281810078497&sdata=ipyVLaXhefjwhIPqu4Vym3Nmi%2FXPER8hyKBDvP%2FAVCw%3D&reserved=0
>>    
>> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftoo
>> ls.ietf.org%2Fhtml%2Fdraft-ietf-oauth-native-apps-08&data=02%7C01%7Ct
>> onynad%40microsoft.com%7Ceff092e6b2894ace8f8408d464cda4d5%7C72f988bf8
>> 6f141af91ab2d7cd011db47%7C1%7C0%7C636244281810088501&sdata=pFJdiZd2ni
>> SxiuXtThG8OE32rjHxoJ8U0jsoCmiaqKc%3D&reserved=0>
>> 
>>    A diff from the previous version is available at:
>>    
>> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Frfcdiff%3Furl2%3Ddraft-ietf-oauth-native-apps-08&data=02%7C01%7Ctonynad%40microsoft.com%7Ceff092e6b2894ace8f8408d464cda4d5%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636244281810088501&sdata=0JOejYI%2F9vSFph4dteZ6g16NbvLRy37erpRUAw2q%2FW8%3D&reserved=0
>>    
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>> 2f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636244281810088501&sdata=0J
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>> 
>> 
>>    Please note that it may take a couple of minutes from the time of
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>>    Internet-Drafts are also available by anonymous FTP at:
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