Thanks for the feedback Dan. I have created a couple of GitHub issues to
address all of these.

1. https://github.com/oauth-wg/oauth-cross-device-security/issues/164
2. https://github.com/oauth-wg/oauth-cross-device-security/issues/165
3. https://github.com/oauth-wg/oauth-cross-device-security/issues/166
4. https://github.com/oauth-wg/oauth-cross-device-security/issues/167
5. https://github.com/oauth-wg/oauth-cross-device-security/issues/168

Cheers

Pieter

On Tue, Jul 1, 2025 at 7:42 PM Dan Moore <[email protected]> wrote:

> Hi folks,
>
> This was a super useful document. I thought all the examples and
> delineations were very helpful in making a tough topic understandable.
>
> A few comments/nits:
>
> Links in this section
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#name-defending-against-cross-dev
> don't point to the correct anchor/aren't processed.
>
> In the Examples section (3.3) there were some inconsistencies:
>
> - this section is "Cross-Device Session Transfer Pattern" rather than
> "Session Transfer Pattern":
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#section-3.3.5
> doing so makes it consistent with the other parenthesized pattern names,
> which all refer to the specific pattern name used above.
> - same issue with
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#section-3.3.7
>
> In section 4.3, some of the parenthesized text doesn't tie back to the
> patterns:
> - this section:
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#section-4.3.6
> - this section:
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#section-4.3.8
>
> These are the only ones with the "suffix" exploit, everything else is a
> "pattern".
>
> Typo:
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#section-5-5
> has an upper case S in server: "An authorization Server" it should be
> lowercase for consistency.
>
> In this section,
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#name-mitigating-against-cross-de
> I'd modify this sentence:
> 'End-users have "expertise elsewhere" and are typically not security
> experts and don't understand the protocols and systems they interact with.'
> to use commas
> 'End-users have "expertise elsewhere", are typically not security experts,
> and don't understand the protocols and systems they interact with.'
>
> In this section
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#section-6.1.1-2.3.1
> I'd add that the shared network check breaks down if the consumption device
> (TV) is on wifi and the authorization device (mobile phone) is on the
> mobile network, a common situation.
>
> In this section:
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#section-6.1.1-1
> When the doc suggests "There are a couple of ways to establish proximity"
> is it worth being explicit that the authorization server is the entity that
> is responsible for this? It is implied.
>
> The mitigations section was great! I wondered if it made sense to break
> mitigations out further between those that the authorization server can
> implement (limited scopes, short lived tokens) and those that require work
> across other systems (such as content filtering, trusted devices). An
> alternative might be including that info in the table in 6.1.18.
>
> This section has some extra hash marks:
>
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#name-ietf-oauth-20-device-author
> . Saw the same with 6.2.2 and 6.2.3.
>
> There are some busted internal anchor links here:
> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html#section-6.3-6.2.1
>
> Thanks,
> Dan
>
>
> On Tue, Jun 17, 2025 at 8:34 AM Pieter Kasselman <[email protected]> wrote:
>
>> Dear chairs
>>
>> Thanks for the shepherd feedback on the Cross-Device Flows: Security Best
>> Current Practice draft provided at IETF 122.
>>
>> The below draft includes updates to address the feedback received.
>>
>> Please advise on the next steps for this draft.
>>
>> Cheers
>>
>> Pieter
>>
>> On Tue, Jun 17, 2025 at 3:19 PM <[email protected]> wrote:
>>
>>> Internet-Draft draft-ietf-oauth-cross-device-security-10.txt is now
>>> available.
>>> It is a work item of the Web Authorization Protocol (OAUTH) WG of the
>>> IETF.
>>>
>>>    Title:   Cross-Device Flows: Security Best Current Practice
>>>    Authors: Pieter Kasselmann
>>>             Daniel Fett
>>>             Filip Skokan
>>>    Name:    draft-ietf-oauth-cross-device-security-10.txt
>>>    Pages:   58
>>>    Dates:   2025-06-17
>>>
>>> Abstract:
>>>
>>>    This document describes threats against cross-device flows along with
>>>    practical mitigations, protocol selection guidance, and a summary of
>>>    formal analysis results identified as relevant to the security of
>>>    cross-device flows.  It serves as a security guide to system
>>>    designers, architects, product managers, security specialists, fraud
>>>    analysts and engineers implementing cross-device flows.
>>>
>>> The IETF datatracker status page for this Internet-Draft is:
>>> https://datatracker.ietf.org/doc/draft-ietf-oauth-cross-device-security/
>>>
>>> There is also an HTML version available at:
>>>
>>> https://www.ietf.org/archive/id/draft-ietf-oauth-cross-device-security-10.html
>>>
>>> A diff from the previous version is available at:
>>>
>>> https://author-tools.ietf.org/iddiff?url2=draft-ietf-oauth-cross-device-security-10
>>>
>>> Internet-Drafts are also available by rsync at:
>>> rsync.ietf.org::internet-drafts
>>>
>>>
>>> _______________________________________________
>>> OAuth mailing list -- [email protected]
>>> To unsubscribe send an email to [email protected]
>>>
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