The more I think about this the more I think that HoK is really more or an
informational type RFC if anything. If you really want a cleartext part so as
not to encrypt a certificate or something then OK, but in the end all our
extant token types can support the HoK token payload. In profiles where we
already have a transaction signature nothing more is needed. And if you want
to apply it to something like Bearer, then you should be using MAC instead.
We could theoretically wedge it in to the client authentication mechanism, but
why?
________________________________
From: William Mills <wmills_92...@yahoo.com>
To: Hannes Tschofenig <hannes.tschofe...@gmx.net>
Cc: "oauth@ietf.org" <oauth@ietf.org>
Sent: Wednesday, July 11, 2012 9:52 AM
Subject: Re: [OAUTH-WG] Holder-of-the-Key for OAuth
Having re-read this I think I now understand how symmetric would work. In the
HOK model as I think of it we have 3 basic parts: opaque token stuff, asserted
client key, and server signature. The asserted client key could be:
-a public key
-a certificate
-an encrypted symmetric key
-other?
For symmetric key it would act as a key distribution for clients to the
endpoints, so it would be doing a similar thing for symmetric keys that it
would for PK, e.g. key distribution and trust. In the end the token itself can
contain the asserted key, MAC tokens can support this concept now in fact. The
relying endpoint would extract the secret from the token to check the
signature. For the PK case you don't have to encrypt the asserted key, which
is a little cheaper.
-bill
________________________________
From: Hannes Tschofenig <hannes.tschofe...@gmx.net>
To: William Mills <wmills_92...@yahoo.com>
Cc: Hannes Tschofenig <hannes.tschofe...@gmx.net>; prateek mishra
<prateek.mis...@oracle.com>; "Tschofenig, Hannes (NSN - FI/Espoo)"
<hannes.tschofe...@nsn.com>; "oauth@ietf.org" <oauth@ietf.org>
Sent: Tuesday, July 10, 2012 11:23 PM
Subject: Re: [OAUTH-WG] Holder-of-the-Key for OAuth
I also fail to see the value of a symmetric holder-of-the-key solution and I
don't buy the performance argument either (particularly since we are using a
short key length here.
I hope that this is not the "let us replicate all the work we had done in some
other crazy enterprise identity management solution so far." approach.
On Jul 10, 2012, at 11:26 PM, William Mills wrote:
> OK, but why do you need holder-of-key then? I think holder-of-key gets
> significantly weird in the symmetric key case. In the PKI case the token
> has (public_key, token, signature(public_key, token, serversecret)). How
> will the server assert something in the credential that's useful in place of
> a plublic key (or certificate)? I think the best case there is that the
> server is asserting a client name which the protected resource uses to look
> up the symmetric key to use for the signature check, but that could just be
> included in
token anyway without holder-of-key.
>
> I really don't see how this works with symmetric keys in any useful way
> that's not easier via another method like MAC tokens?
>
>
> From: prateek mishra <prateek.mis...@oracle.com>
> To: "Tschofenig, Hannes (NSN - FI/Espoo)" <hannes.tschofe...@nsn.com>
> Cc: oauth@ietf.org
> Sent: Tuesday, July 10, 2012 12:00 PM
> Subject: Re: [OAUTH-WG] Holder-of-the-Key for OAuth
>
> Hannes,
>
> we have a variety of use-cases wherein a single server ("client") repeatedly
> interacts with a resource server for business purposes. These interactions
> may be on-behalf-of
> a single user or
even multiple users. In such a use-case, use of assymetric signature imposes
an unacceptable performance penalty and there is a lot of interest in being able
> to use symmetric signature instead.
>
> - prateek
>> Hi Prateek,
>>
>> why do you care about the symmetric key case?
>> Specifying more variants requires more code and decreases interoperability.
>>
>> Ciao
>> Hannes
>>
>>
>> From: oauth-boun...@ietf.org [mailto:oauth-boun...@ietf.org] On Behalf Of
>> ext prateek mishra
>> Sent: Tuesday, July 10, 2012 8:42 PM
>> To: oauth@ietf.org
>> Subject: Re: [OAUTH-WG]
Holder-of-the-Key for OAuth
>>
>> As Phil Hunt suggests, there is a need for a discussion of the use-cases
>> involved
>>
>> How to bind the key to the requestor may have several variations, I would
>> hope the work would cover a broad range
>>
>> Given the importance of the symmetric key case, I would also be interested
>> in key establishment methods as well
>>
>>
>>
>> When I say arguably, I expect you to argue.
>>
>> John B.
>>
>> Sent from my iPhone
>>
>> On 2012-07-10, at 1:01 PM, Anthony Nadalin <tony...@microsoft.com> wrote:
>>
>> Binding the key to the channel is arguably the most secure
>>
>> Not really, there are hardware
options that give good security properties
>>
>> -----Original Message-----
>> From: John Bradley [mailto:ve7...@ve7jtb.com]
>> Sent: Tuesday, July 10, 2012 9:55 AM
>> To: Hannes Tschofenig
>> Cc: Anthony Nadalin; Hannes Tschofenig; OAuth WG
>> Subject: Re: [OAUTH-WG] Holder-of-the-Key for OAuth
>>
>> Binding the key to the channel is arguably the most secure.
>>
>> SSL offloading and other factors may prevent that from working in all cases.
>>
>> I suspect that we will need two OAuth bindings. One for TLS and one for
>> signed message.
>>
>> John B.
>>
>> Sent from my iPhone
>>
>> On 2012-07-10, at 12:11 PM, Hannes Tschofenig <hannes.tschofe...@gmx.net>
>> wrote:
>>
>> If we do not bind the key to the channel than we will run into all sorts of
>> problems. The current MAC specification illustrates that quite nicely. On
>> top of that you can re-use the established security channel for the actual
>> data exchange.
>>
>> On Jul 10, 2012, at 5:29 PM, Anthony Nadalin wrote:
>>
>> One question is if we want to do a generic proof of possession for JWT that
>> is useful outside OAuth, or something OAuth specific. The answer may be
>> a combined approach.
>>
>> Depends if we want OAuth to support the concept of a request/response for a
>> proof token and keep the actual binding for a separate specification, in
>> most of our cases the keying material is opaque (and just a blob), where we
>> care
about the key material is in the key agreement (entropy) cases.
>>
>> -----Original Message-----
>> From: John Bradley [mailto:ve7...@ve7jtb.com]
>> Sent: Tuesday, July 10, 2012 3:34 AM
>> To: Hannes Tschofenig
>> Cc: Anthony Nadalin; OAuth WG
>> Subject: Re: [OAUTH-WG] Holder-of-the-Key for OAuth
>>
>> I agree that there are use-cases for all of the proof of possession
>> mechanisms.
>>
>> Presentment methods also need to be considered.
>>
>> TLS client auth may not always be the best option. Sometimes message
>> signing is more appropriate.
>>
>> One question is if we want to do a generic proof of possession for JWT that
>> is useful outside OAuth, or something OAuth specific.
The answer may be a combined approach.
>>
>> I think this is a good start to get discussion going.
>>
>> John B.
>> On 2012-07-09, at 3:05 PM, Hannes Tschofenig wrote:
>>
>> Hi Tony,
>>
>> I had to start somewhere. I had chosen the asymmetric version since it
>> provides good security properties and there is already the BrowserID/OBC
>> work that I had in the back of my mind. I am particularly interested to
>> illustrate that you can accomplish the same, if not better, characteristics
>> than BrowserID by using OAuth instead of starting from scratch.
>>
>> Regarding the symmetric keys: The asymmetric key can be re-used but with a
>> symmetric key holder-of-the-key you would have to request a fresh one every
>> time in order to accomplish comparable security benefits.
>>
>> Ciao
>>
Hannes
>>
>> On Jul 9, 2012, at 9:57 PM, Anthony Nadalin wrote:
>>
>> Hannes, thanks for drafting this, couple of comments:
>>
>> 1. HOK is one of Proof of Possession methods, should we consider others?
>> 2. This seems just to handle asymmetric keys, need to also handle symmetric
>> keys
>>
>>
>> -----Original Message-----
>> From: oauth-boun...@ietf.org [mailto:oauth-boun...@ietf.org] On Behalf Of
>> Hannes Tschofenig
>> Sent: Monday, July 09, 2012 11:15 AM
>> To: OAuth WG
>> Subject: [OAUTH-WG] Holder-of-the-Key for OAuth
>>
>> Hi guys,
>>
>> today I submitted a short document
that illustrates the concept of holder-of-the-key for OAuth.
>> Here is the document:
>> https://datatracker.ietf.org/doc/draft-tschofenig-oauth-hotk
>>
>> Your feedback is welcome
>>
>> Ciao
>> Hannes
>>
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