[Openid-specs-heart] Comment on Section 2.1.3 of Health Relationship Trust Profile for OAuth 2.0
Justin Richer
jricher at mit.edu
Thu Dec 3 23:54:47 UTC 2015
I'm not sure that key is used for what you think it's used for. That
public key is the public key /of the AS /and it is likely a single key
for all clients and protected resources. The tokens are signed with this
key but the transactions/requests/resources are not. Only the AS can
prove possession of this key, which is kinda the point: only the AS can
mint tokens from the AS. The RS does not establish this key. The RS does
not have the private key for this public key. Nor does the client. Each
AS will have its own key, which is published at its own URL. These keys
will be there regardless of what kinds of clients or RS's are attached
to the AS.
Technically you could use a different key to sign every access token
that you put out, but what does that buy you? I can see no benefit of
doing that since every RS will validate the signature separately, if it
does so at all. The RS can ignore the signature on this token and use
introspection to validate it at runtime. After all, in many
circumstances and deployments, a self-contained token should not be
enough. The client ignores it entirely and just passes the token through
opaquely.
The kind of legal protection you're talking about has nothing to do with
public keys or signatures. An evil client will only have access to
whatever it was delegated by nature of the AS being the only entity in
the system capable of minting tokens that the RS will accept. This is
OAuth 101 and has nothing to do with the format of the token or the
server's possession of a keypair. As stated above, the RS can verify the
token without any knowledge of the key and signature.
What the legal question does have to do with is auditability of the
transaction. That's where the conversation on auditable transaction
receipts came in at IIW this year, and that's something that can (and
should) be built on top of all of this as a separate layer. That is not
part of this current work.
So, I still say that nothing you're saying makes any sense to me.
-- Justin
On 12/3/2015 6:12 PM, Adrian Gropper wrote:
> The public key I'm talking about is (*emphasis added*)
>
>
> 4.1.
> <http://openid.bitbucket.org/HEART/openid-heart-oauth2.html#rfc.section.4.1>
> Discovery
> <http://openid.bitbucket.org/HEART/openid-heart-oauth2.html#Discovery>
>
> The authorization server MUST provide an OpenID Connect service
> discovery
> <http://openid.bitbucket.org/HEART/openid-heart-oauth2.html#OpenID.Discovery>
> [OpenID.Discovery] endpoint listing the components relevant to the
> OAuth protocol:
>
> issuer
> The fully qualified issuer URL of the server
> authorization_endpoint
> The fully qualified URL of the server's authorization endpoint
> defined by OAuth 2.0
> <http://openid.bitbucket.org/HEART/openid-heart-oauth2.html#RFC6749>
> [RFC6749]
> token_endpoint
> The fully qualified URL of the server's token endpoint defined by
> OAuth 2.0
> <http://openid.bitbucket.org/HEART/openid-heart-oauth2.html#RFC6749>
> [RFC6749]
> introspection_endpoint
> The fully qualified URL of the server's introspection endpoint
> defined by OAuth Token Introspection
> <http://openid.bitbucket.org/HEART/openid-heart-oauth2.html#RFC7662>
> [RFC7662]
> revocation_endpoint
> The fully qualified URL of the server's revocation endpoint
> defined by OAuth 2.0 Token Revocation
> <http://openid.bitbucket.org/HEART/openid-heart-oauth2.html#RFC7009>
> [RFC7009]
> jwks_uri
> The fully qualified URI of *the server's public key* in JWK Set
> <http://openid.bitbucket.org/HEART/openid-heart-oauth2.html#RFC7517>
> [RFC7517] format
>
> I never mentioned encryption. I understand that all of the encryption
> in HEART is done by the SSL certificates that every server (RS and AS)
> has to have.
>
> What I'm trying to make clear, is that each HEART protected resource,
> regardless of who specifies the AS and what kind of client is seeking
> access can have its own separate public key that is provided by the AS
> as part of 4.1 above. Is this statement consistent with the three
> HEART profiles as proposed?
>
> The reason that I'm being a stickler on this point is a liability
> issue from the resource server's perspective. I want to make sure that
> the RS can claim a legal safe harbor for breach of a protected
> resource as long as it can show that only that AS, as specified in 4.1
> above, could have delegated access to whatever client shows up asking
> for the resource. An unverified and evil client, for example, should
> have access to only one patient regardless of how evil it is. This
> puts the burden of client and RqP verification completely on the
> shoulders of the AS that is doing the resource registration dance 4.1.
> Hence the "safe harbor" when the RS can prove that the RO specified
> the AS.
>
> PS: This has nothing to do with the RHEx situation where the RS was
> expected to take responsibility for registration of the client and
> authentication of the RqP. The RS was on the hook for a lot more in
> RHEx. The RS is also on the hook for a lot more when the RS specifies
> the AS, as it can in OAuth.
>
> Adrian
>
> On Thu, Dec 3, 2015 at 4:48 PM, Justin Richer <jricher at mit.edu
> <mailto:jricher at mit.edu>> wrote:
>
> Adrian,
>
> I’m still not sure where you’re getting public keys from. It
> sounds like you’re proposing a completely different technology
> stack which, as far as I’m aware, doesn’t exist.
>
> — Justin
>
>> On Dec 3, 2015, at 4:05 PM, Adrian Gropper
>> <agropper at healthurl.com <mailto:agropper at healthurl.com>> wrote:
>>
>> Thanks Dale for raising this important issue. One of the problems
>> is that the term "resource owner" is overloaded and that makes
>> the discussion of OAuth vs. UMA unnecessarily complex. The point
>> you are raising is directly related to the ONC API Task Force
>> that was just created and guidance that might be issued by OCR on
>> the patient right of access to the MU3 API.
>>
>> Resource owner is confusing in HEART because it could be:
>> - the Resource Subject (the person, including a child or a
>> disabled elder) that a FHIR resource pertains to
>> - the Resource Delegate (the person that has access to technology
>> and the (legal) right to manage a FHIR resource
>> - the Resource Custodian, that has the right to delete the
>> resource and is typically responsible for protecting access. This
>> is typically a HIPAA covered entity such as the hospital, lab, or
>> insurance co that exposes a FHIR resource pertaining to a single
>> subject.
>>
>> Section 2 of the HEART OAuth 2.0 Profile
>> http://openid.bitbucket.org/HEART/openid-heart-oauth2.html is
>> confusing in this respect and it makes the transition to the
>> HEART UMA Profile
>> http://openid.bitbucket.org/HEART/openid-heart-uma.html
>> particularly difficult.
>>
>> The majority of my comments around these drafts have to do with
>> this overloading of the "resource owner" term. The HEART
>> "delegation" use-case is partly designed to resolve this
>> ambiguity. This is also why I suggest that for both security and
>> interoperability UMA is easier to profile than OAuth.
>>
>> The HEART profiles do not need to deal with multi-subject bulk
>> transfers, transfers from Alice to Alice, and resources that
>> pertain to multiple subjects such as a patient list. These can be
>> done in other ways or can be added to HEART later. In order to
>> inform the MU3 API requirement, and to allow a broad
>> interpretation of "patient right of access" with security safe
>> harbors for the HIPAA CE, the HEART profiles must allow the
>> Authorization Server to register clients and authenticate
>> requesting parties without any blocking by the resource server.
>> This is achievable when every resource can be protected by a
>> separate public key link that is provided by the AS at resource
>> registration time. I believe that the current profiles allow for
>> this during dynamic registration of the AS, but I certainly think
>> it could be clearer.
>>
>> Adrian
>>
>> On Thu, Dec 3, 2015 at 12:32 PM, Dale Moberg
>> <dale.moberg at orionhealth.com
>> <mailto:dale.moberg at orionhealth.com>> wrote:
>>
>>
>> Hi, with advance apologies for the holiday-induced delay to
>> our editor.
>>
>> Section 2.0 introduces three Client Profiles Types in
>> sections 2.1.1 + 2.1.2 and section 2.1.3. I agree with others
>> in the group that the Client Profile types do present
>> “vanilla” profiles for three of the now five specified OAuth2
>> token grant types (found in RFCs 6749 7521).
>> The Full Client and Browser Embedded clients with User
>> delegation are certain to be of value in healthcare (and for
>> the OAuth2-protected security services of UMA and OpenId
>> Connect).
>>
>> I do, however, have concerns about any inter-organizational
>> uses of the Direct Access Client type in healthcare that I
>> wish to present next. I would advocate deferring
>> implementation of the Direct Access client type until more is
>> agreed upon the intended usage of this pattern. If the only
>> real usage is for “internal” bulk downloads, then
>> organizations are free to accomplish downloads in several
>> ways, including a Direct Access client pattern if they wish.
>> Internal usage can proceed without standards that support
>> interoperability; private or proprietary solutions could
>> suffice. But, if the pattern is implemented for
>> inter-organizational data sharing, the Direct Access client
>> type has several deficiencies.
>>
>> OAuth2 Full Client types allow a “resource owner” to delegate
>> access to a Client application. While our group often is
>> thinking about important healthcare use cases where resource
>> owners and resource sets map, respectively, to patients and
>> their medical records, nothing requires restricting the
>> pattern in this way. For example, a physician might be a
>> resource owner (and be entitled to both read and delegate
>> access) to all of his patient records to others involved in
>> patient care, by referrals or other processes. What counts
>> semantically in “owner” is that an end user has a userid and
>> password that, in combination with a registered client and
>> its secret is granted access to a set of resources.
>>
>> So it could be that for a given resource set, there are
>> multiple owners (accessors) able to present credentials and
>> ids and delegate access to a resource set to registered
>> clients presenting their credentials. Or there could be one
>> owner. Bank accounts, facebook pages, google docs – all
>> exhibit their own distinctive requirements for privacy and
>> sharing, and it is at a policy level that these requirements
>> get mulled over and policies get thrashed out.
>>
>> As a mechanism of requesting and granting or refusing access,
>> the Direct Client type does not mesh well with
>> interorganizational access requests because of some specifics
>> about the healthcare domain.
>>
>> First, direct access clients are not to be dynamically
>> registered (according to our profile) -- which is very sensible.
>>
>> So registration must be for a client that “on its own” is
>> trusted with resources. Now suppose that the resource pool
>> (the set of all resource sets) exposes an API that is to
>> support Direct Access Clients. And suppose that the Client is
>> not in the security domain of the resource or authorization
>> servers. Clearly there needs to be considerable trust
>> extended to allow registration of such a client. Because once
>> registered, the access authorization check—no matter what
>> resource is requested-- can only be based on the client_id
>> and the accompanying client_secret. On this basis, a JWT
>> (access token) is issued – containing no more specific or
>> granular information about the requester than its
>> organizational identity; the resource server can check the
>> JWT, is signature and make a call to an introspection
>> service. But the authorization service, once trusted, has
>> said access is permitted, no matter what the resource
>> happened to be, provided the client id and secret are OK.
>>
>> Now conceivably there are organizations with data to be
>> shared that could leverage organizational identity as a basis
>> for data sharing. A producer of goods might request access to
>> a data base to see all goods purchased by a retailer, and
>> based on which organization is requesting, disallow a
>> producer from seeing how much the retailer had purchased from
>> a competing producer, but still see its own products that had
>> been purchased.But healthcare data sharing is governed by
>> privacy regulations that reflect such challenges as “who’s
>> asking?” “what is their role?" and “what’s your need to know
>> with respect to healthcare provision?” Depending on the
>> answers to these questions, tied to the identity and role(s)
>> of the requesters and their healthcare relevant relationships
>> to the patients/customers, access is granted. The problem
>> with the Direct Access client is that the information needed
>> to check the policy is not provided in the request. A
>> significant side effect would be that no audit trail could be
>> produced to document who got the information and in what
>> capacity and circumstances the information is to be used.
>>
>> The problem is that the requesting organization has the
>> relevant information about the user(s), role(s) and
>> relationships to the patients but it is not information
>> available in the registration, in the access request, or as
>> an intrinsic part of the client-credentials-only flow used in
>> the Direct Access Client type. The inter-organizational
>> trust/access problem can be succinctly described by noting
>> that we expect the authorization/resource organization to be
>> able to consult the same information about the Direct Access
>> client access request approval identities, roles, and
>> relationships as is used for an internal system request. And
>> the Direct Client pattern lacks specification of ways that
>> the information, or an explanation of how to obtain the
>> information, that is needed for checking that typical
>> healthcare policies apply.
>>
>> If implementers think that the Direct Access Client support
>> would be important to offer “inside the four walls” -- to use
>> one of our expert’s vivid phrase — then I suppose the profile
>> could be released with that understanding of its intended
>> application range. I would urge the committee to consider
>> very carefully whether they are sufficiently comfortable with
>> the inter-organizational/inter-regional/inter-security-domain
>> security issues to recommend implementation for that context
>> of use.
>>
>> Dale Moberg
>>
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>>
>>
>>
>> --
>>
>> Adrian Gropper MD
>>
>> PROTECT YOUR FUTURE - RESTORE Health Privacy!
>> HELP us fight for the right to control personal health data.
>> DONATE: http://patientprivacyrights.org/donate-2/
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>
>
>
> --
>
> Adrian Gropper MD
>
> PROTECT YOUR FUTURE - RESTORE Health Privacy!
> HELP us fight for the right to control personal health data.
> DONATE: http://patientprivacyrights.org/donate-2/
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