Hi Rob, > On 22. Nov 2019, at 16:10, Rob Otto > <robotto=40pingidentity....@dmarc.ietf.org> wrote: > > Hi Torsten - thanks for the reply.. > > Responses in line. > > Grüsse > Rob > > On Fri, 22 Nov 2019 at 07:59, Torsten Lodderstedt > <torsten=40lodderstedt....@dmarc.ietf.org> wrote: > Hi Rob, > > > On 22. Nov 2019, at 15:52, Rob Otto > > <robotto=40pingidentity....@dmarc..ietf.org> wrote: > > > > Hi everyone > > > > I'd agree with this. I'm looking at DPOP as an alternative and ultimately > > simpler way to accomplish what we can already do with MTLS-bound Access > > Tokens, for use cases such as the ones we address in Open Banking; these > > are API transactions that demand a high level of assurance and as such we > > absolutely must have a mechanism to constrain those tokens to the intended > > bearer. Requiring MTLS across the ecosystem, however, adds significant > > overhead in terms of infrastructural complexity and is always going to > > limit the extent to which such a model can scale. > > I would like to unterstand why mTLS adds “significant overhead in terms of > infrastructural complexity”. Can you please dig into details? > > I guess it's mostly that every RS-endpoint (or what sits in front of it) has > to have a mechanism for accepting/terminating mTLS, managing roots of trust, > validating/OCSP, etc
You use a PKI then. We use mTLS with self-signed certs. That requires the RS to not check the X.509 trust chain, which requires a special setting (optionalNoCA). > and then passing the certificates downstream as headers. None of it is > necessarily difficult or impossible to do in isolation, but I meet many many > people every week who simply don't know how to do any of this stuff. And > these are typically "network people", for want of a better word. There are > quite a few SaaS API management and edge solutions out there that don't even > support mTLS at all. You also have the difficulty in handling a combination > of MTLS and non-MTLS traffic to the same endpoints. yep. You better split them, especially if that’s a user facing endpoint. > Again, it's possible to do, but far from straightforward. > > > > Our experience so far: It can be a headache to set up in a microservice > architecture with TLS terminating proxies but once it runs it’s ok. On the > other side, it’s easy to use for client developers and it combines client > authentication and sender constraining nicely. > > I do think its an elegant solution, don't get me wrong. It's just that there > are plenty of moving parts that you need to get right and that can be a > challenge, particularly in large, complex environments. I agree. I also tend there is a tendency to think Client TLS authentication is bad. I understand that from historical and recent experience with PKI. But anybody considering to use a application level signing solution based on _raw_ public keys should directly move towards self-signed certificates. That brings you all the benefits of TLS without the (PKI) headache. > > > > > > > DPOP, to me, appears to be a rather more elegant way of solving the same > > problem, with the benefit of significantly reducing the complexity of (and > > dependency on) the transport layer. I would not argue, however, that it is > > meant to be a solution intended for ubiquitous adoption across all > > OAuth-protected API traffic. Clients still need to manage private keys > > under this model and my experience is that there is typically a steep > > learning curve for developers to negotiate any time you introduce a > > requirement to hold and use keys within an application. > > My experience is most developer don’t even get the URL right (in the > signature and the value used on the receiving end). So the total cost of > ownership is increased by numerous support inquiries. > I'll not comment, at the risk of offending developers :) Alright. Ultimately, I just want to get in touch with those who respond :-) best regards, Torsten. > > best regards, > Torsten. > > > > > I guess I'm with Justin - let's look at DPOP as an alternative to > > MTLS-bound tokens for high-assurance use cases, at least initially, without > > trying to make it solve every problem. > > > > Best regards > > Rob > > > > > > On Fri, 22 Nov 2019 at 07:24, Justin Richer <jric...@mit.edu> wrote: > > I’m going to +1 Dick and Annabelle’s question about the scope here. That > > was the one major thing that struck me during the DPoP discussions in > > Singapore yesterday: we don’t seem to agree on what DPoP is for. Some > > (including the authors, it seems) see it as a quick point-solution to a > > specific use case. Others see it as a general PoP mechanism. > > > > If it’s the former, then it should be explicitly tied to one specific set > > of things. If it’s the latter, then it needs to be expanded. > > > > I’ll repeat what I said at the mic line: My take is that we should > > explicitly narrow down DPoP so that it does exactly one thing and solves > > one narrow use case. And for a general solution? Let’s move that discussion > > into the next major revision of the protocol where we’ll have a bit more > > running room to figure things out.. > > > > — Justin > > > >> On Nov 22, 2019, at 3:13 PM, Dick Hardt <dick.ha...@gmail.com> wrote: > >> > >> > >> > >> On Fri, Nov 22, 2019 at 3:08 PM Neil Madden <neil.mad...@forgerock.com> > >> wrote: > >> On 22 Nov 2019, at 01:42, Richard Backman, Annabelle <richa...@amazon.com> > >> wrote: > >>> There are key distribution challenges with that if you are doing > >>> validation at the RS, but validation at the RS using either approach > >>> means you’ve lost protection against replay by the RS. This brings us > >>> back to a core question: what threats are in scope for DPoP, and in what > >>> contexts? > >> > >> Agreed, but validation at the RS is premature optimisation in many cases. > >> And if you do need protection against that the client can even append a > >> confirmation key as a caveat and retrospectively upgrade a bearer token to > >> a pop token. They can even do transfer of ownership by creating copies of > >> the original token bound to other certificates/public keys. > >> > >> While validation at the RS may be an optimization in many cases, it is > >> still a requirement for deployments. > >> > >> I echo Annabelle's last question: what threats are in scope (and out of > >> scope) for DPoP? > >> > >> > >> _______________________________________________ > >> OAuth mailing list > >> OAuth@ietf.org > >> https://www.ietf.org/mailman/listinfo/oauth > > > > _______________________________________________ > > OAuth mailing list > > OAuth@ietf.org > > https://www.ietf.org/mailman/listinfo/oauth > > > > > > -- > > > > Rob Otto > > EMEA Field CTO/Solutions Architect > > roberto...@pingidentity.com > > > > c: +44 (0) 777 135 6092 > > Connect with us: > > > > > > > > > > CONFIDENTIALITY NOTICE: This email may contain confidential and privileged > > material for the sole use of the intended recipient(s). Any review, use, > > distribution or disclosure by others is strictly prohibited.. If you have > > received this communication in error, please notify the sender immediately > > by e-mail and delete the message and any file attachments from your > > computer. Thank you._______________________________________________ > > OAuth mailing list > > OAuth@ietf.org > > https://www.ietf.org/mailman/listinfo/oauth > > > > -- > > Rob Otto > EMEA Field CTO/Solutions Architect > roberto...@pingidentity.com > > c: +44 (0) 777 135 6092 > Connect with us: > > > > > CONFIDENTIALITY NOTICE: This email may contain confidential and privileged > material for the sole use of the intended recipient(s). Any review, use, > distribution or disclosure by others is strictly prohibited.. If you have > received this communication in error, please notify the sender immediately by > e-mail and delete the message and any file attachments from your computer. > Thank you.
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