[IPP] OAuth in IPP and the "oauth-authorization-server-uri" IPP attribute

[IPP] OAuth in IPP and the "oauth-authorization-server-uri" IPP attribute

[IPP] OAuth in IPP and the "oauth-authorization-server-uri" IPP attribute

Kennedy, Smith (Wireless Architect) smith.kennedy at hp.com
Tue Jul 25 03:35:33 UTC 2017



> On Jul 24, 2017, at 2:33 PM, Michael Sweet <msweet at apple.com> wrote:
> 
> Smith,
> 
> PWG 5100.18 is IPP INFRA... :)
> 

Eeek - how did I make that mistake?  :p 

> The "oauth-authorization-server-uri" Printer Description attribute specifies the OAuth server that the printer uses (and thus the client must use to obtain a bearer token) - this is needed because RFC 6750's WWW-Authenticate header does not include the authorization server...
> 
> OAuth Bearer tokens (used for HTTP authentication) do NOT rely on redirection, but instead use a cached token string that the Client obtains by going to the auth server.  Think Github API tokens...
> 
> The "access-oauth-token" member attribute contains the bearer token for the specified remote resource, and is how you provide third-party access to a resource.  The "access-oauth-uri" points to the OAuth server used.  The Printer uses the "access-oauth-token" value in the HTTP Authentication field, e.g.:
> 
>    Authentication: Bearer dflkjfler232rsdlfkj45efdlk12fasf

I'm clearly not an OAuth2 expert, but the diagram I have in my "IPP Authentication" deck, with an HTTP 302 Found redirection seems to be describing a different use of OAuth2 authentication than what is outlined in RFC 6750 - is that a fair statement? IPP INFRA didn't mention RFC 6750 so the distinction is not clear. And are you saying that an OAuth2 "Access Token" is NOT a supported authentication mechanism for IPP? (Am I reading this right?) Is this because you are trying to control access on a per-resource basis?

Do we need additional keywords for "uri-authentication-supported" to make it clear that 'oauth' refers to OAuth2 Bearer authentication [RFC6750]? (What about kerberos?)


> 
> 
>> On Jul 24, 2017, at 2:37 PM, Kennedy, Smith (Wireless Architect) <smith.kennedy at hp.com> wrote:
>> 
>> Greetings,
>> 
>> I am working on converting the "IPP Authentication" slide set to a whitepaper. In the process, I've been considering OAuth a bit more. PWG 5100.18 (IPP Transaction Based Printer Extensions) defines the "oauth-authorization-server-uri", "access-oauth-token", and "access-oauth-uri" attributes. It isn't clear to me how these attributes integrate into an OAuth authentication system. 
>> 
>> The way that OAuth / OAuth2 seems to work, there will be an HTTP response redirecting the User Agent (IPP Client) to a different server for authentication. If this is all handled at the HTTP layer, what value do these IPP attributes provide?
>> 
>> Thanks for any help,
>> 
>> Smith
>> 
>> /**
>>   Smith Kennedy
>>   Wireless Architect - Client Software - IPG-PPS
>>   Standards - IEEE ISTO PWG / Bluetooth SIG / Wi-Fi Alliance / NFC Forum / USB IF
>>   Chair, IEEE ISTO Printer Working Group
>>   HP Inc.
>> */
>> 
>> 
>> 
>> _______________________________________________
>> ipp mailing list
>> ipp at pwg.org
>> https://www.pwg.org/mailman/listinfo/ipp
> 
> _________________________________________________________
> Michael Sweet, Senior Printing System Engineer
> 

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