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Get Access Token [ITI-71]

This section describes the national extension for the Swiss EPR to the Get Access Token [ITI-71] transaction defined in the IUA profile published in the IHE IT Infrastructure Technical Framework Trial Implementation “Internet User Authorization”. In this transaction, the OAuth Authorization Code grant type option is enforced for security reasons

Scope

The transaction is used by an mHealth App to pass claims to the IUA Authorization Server and to retrieve access token to be used for authorization of the apps access to write data to and retrieve data from the Swiss EPR.

Depending on the claims made by the mHealth App, two different flavors of access tokens are provided by the IUA Authorization Server:

• Basic Access Token – IUA conformal access token authorizing access to the EPR end-points which are NOT protected by the EPR role and attribute based authorization (i.e. for the PIXm endpoints).
• Extended Access Token – IUA conformal access token for the EPR endpoints which are protected by the EPR role and attribute based authorization (i.e. for the MHD endpoints).

An mHealth App in the SMART Standalone Launch sequence SHALL perform the transaction first to get basic access to the Swiss EPR. This requires user authentication as well as the user consent, allowing the mHealth App to access the Swiss EPR and perform transactions on behalf of the user. The IUA Authorization Server SHALL present a User Interface for the user to authenticate and provide user consent, or by validating against data stored at app registration time.

Once the mHealth App is authorized, it may launch other embedded mHealth Apps (or views) using the SMART EHR Launch Sequence. In this case, the embedded app inherits the basic access authorization from the launching app¹ and may retrieve extended access token for EPR endpoints protected by the EPR role and attribute based authorization (e.g. to retrieve documents).

¹By claiming a launch indicator, the launch is indicated as a SMART EHR Launch, initiated from an app, which has already been authorized before.

Actor Roles

Actor: IUA Authorization Client
Role: Communicates launch information and claims to the IUA Authorization Server and receives JWT access token or XUA Authorization Assertion.
Actor: IUA Authorization Server
Role: Verifies claims and authentication information, retrieves and validates the user consent for the mHealth App to act on behalf of the user ² and responds a JWT or XUA compliant access token to the IUA Authorization Client.

²E.g. by presenting a screen for the user to give consent.

Referenced Standards

This national extension does not reference additional standards to the standards referenced in the Get Access Token [ITI-71] transaction of the IUA Trial Implementation.

Messages

OAuth 2.1 authorization code grant flow of the of the IUA Get Access Token transaction:

Trigger Events

A user launches an mHealth App or a specific application view to access data and documents from the Swiss EPR.

Message Semantics

Request

The following table summarizes the requirements on the scope parameter used to convey the claims:

³Token format according FHIR token type.

The scope parameter of the request MAY claim the following attributes:

• There may be a scope with name “launch”. If present, it indicates the permission to obtain launch context for apps (or views) launched in SMART EHR Launch mode. The scope SHALL be used by all apps (or views) launched from a mHealth App which was authorized before.
• There MAY be a scope with name “purpose_of_use=token”. If present, the token SHALL convey the coded value of the current transaction’s purpose of use. Allowed values are NORM (normal access) and EMER (emergency access) from code system 2.16.756.5.30.1.127.3.10.5 of the CH:EPR value set. e.g. purpose_of_use=urn:oid:2.16.756.5.30.1.127.3.10.5|NORM
• There MAY be a scope with name “subject_role=token”. If present, the token SHALL convey the coded value of the subject’s role. The value SHALL be either HCP (healthcare professional), ASS (assistant), REP (representative) or PAT (patient) from code system 2.16.756.5.30.1.127.3.10.6 of the CH:EPR value set. e.g.: subject_role=urn:oid:2.16.756.5.30.1.127.3.10.6|HCP
• There MAY be a scope with name “person_id=value”. If present, the value SHALL convey the EPR-SPID identifier of the patient’s record and the patient assigning authority formatted in CX syntax. e.g: person_id=761337610435209810^^^&2.16.756.5.30.1.109.6.5.3.1.1&ISO

Depending on the value of the role scope additional scopes are required, as described in the following sections.

Healthcare Professional Extension

In the healthcare professional extension, the scope subject_role SHALL be the code HCP from code system 2.16.756.5.30.1.127.3.10.6 of the CH:EPR value set.

Assistant Extension

In the assistant extension, the scope subject_role SHALL be the code ASS from code system 2.16.756.5.30.1.127.3.10.6 of the CH:EPR value set. There SHALL be a scope with name principal_id=value. The value SHALL convey the GLN of the healthcare professional an assistant is acting on behalf of. There SHALL be a scope with name principal=value. The value SHALL convey the name of the healthcare professional an assistant is acting on behalf of. There MAY be one or more scopes with name group_id=value and corresponding group=value. If present each value SHALL convey the ID and name of the subject’s organization or group as registered in the EPR HPD. The ID MUST be an OID in the format of an URN.

Patient Extension

In the patient extension, the scope subject_role SHALL be the code PAT from code system 2.16.756.5.30.1.127.3.10.6 of the CH:EPR value set. The value of the purpose of use scope SHALL be the code NORM from code system 2.16.756.5.30.1.127.3.10.5 of the CH:EPR value set.

Representative Extension

In the representative extension, the scope subject_role SHALL be the code REP from code system 2.16.756.5.30.1.127.3.10.6 of the CH:EPR value set. The token of the purpose_of_use scope SHALL be the code NORM from code system 2.16.756.5.30.1.127.3.10.5 of the CH:EPR value set.

Response

The response SHALL either convey a basic access token in JWT format, granting basic access to the EPR (i.e. to access patient data), or an extended access token to access resources protected by the role and attribute based EPR authorization (i.e. read and write documents).

JSON Web Token Option

The Authorization Server and Resource Server SHALL support the 3.71.4.2.2.1.1 JWT IUA extension with the following claims as defined in Table below.

The claim content for the JWT IUA extensions SHALL correspond to the content defined in the XUA specification (see 1.6.4.2 Get X-User Assertion, A5E1).

The JWT ch_epr extension

The Authorization Server and Resource Server SHALL support the following extensions to the JWT access token for an EPR user:

• user_id: subject identifier according to Annex 5 E1 1.6.4.3.4.2 Message Semantics.

The JWT ch_group extension

The Authorization Server and Resource Server SHALL support the following extensions to the JWT access token for a list of groups a subject is member of:

• name: Name of the organization/group. The name MUST be a string.
• id: The id of the organization/group.The id MUST be an OID in the format of an URN

The ch_group extension claims shall be wrapped in an “extensions” object with key ‘ch_group’ and a JSON array containing the JSON objects with properties name and id. The id MUST be an OID in the format of an URN.

The JWT ch_delegation extension

The Authorization Server and Resource Server shall support the following extensions to the JWT access token:

• principal (optional) Name of the healthcare professional an assistant is acting on behalf of.
• principal_id (optional) GLN of the healthcare professional an assistant is acting on behalf of.

The ch_delegation extension claims shall be wrapped in an “extensions” object with key ‘ch_delegation’ and a JSON value object containing the claims. The claim content for the JWT CH:EPR extensions shall correspond to the content defined in the XUA specification (see 1.6.4.2 Get X-User Assertion, A5E1).

Expected Actions IUA Authorization Client

The IUA Authorization Client SHALL support the HTTP conversation of the OAuth 2.1 Authorization Code grant as follows:

When launched, the IUA Authorization Client SHALL perform HTTP GET request with the URL query parameter as defined in Table and with the scope claims described in Table.

If the IUA Authorization Client receives the request from the IUA Authorization Server on the callback URL conveying the authorization code, it SHALL perform the HTTP POST request with the client_id and client_secret in the HTTP authorization header to resolve the authorization code to the access token.

The IUA Authorization Client SHALL use the access token as defined in IUA Incorporate Access Token transaction, when performing requests to resources of the Swiss EPR⁴.

Expected Actions IUA Authorization Server

The IUA Authorization Server SHALL support the HTTP conversation of the OAuth 2.1 Authorization Code grant as follows:

If the IUA Authorization Server receives a request, it SHALL authenticate the user by redirecting the request to a XUA Authentication Provider⁵. The XUA Authentication provider authenticates the user based on its internal session management (i.e. by checking the requests cookies or other methods) or by validating the user authentication means and returns the identity token to the IUA Authorization Server.

In case of authentication failure, the IUA Authorization Server must respond with HTTP error code 401 ‘Not authorized’.

The IUA Authorization Server SHALL verify the user consent for the mHealth App either by presenting the user a dialog to confirm the required consent, or by validating preregistered contracts.

If the app (or view) is launched as an SMART EHR Launch, the IUA Authorization Server SHALL validate the launch scope parameter, by verifying that the user consent is registered with this launch parameter value. In case of failure, it SHALL respond with HTTP error code 401 ‘Not authorized’.

Depending on the scope claimed, the IUA Authorization Server SHALL either build a basic access authorization token allowing basic access to the EPR (i.e. to access patient data), or an extended access to access resources protected by the role and attribute based EPR authorization (i.e. read and write documents).

The business rules for the IUA Authorization Server for the Healthcare Professional, Assistant, Patient and Representative Extension SHALL be the same as for Annex 5E1 1.6.4.2.4.4 Expected Actions X-Assertion Provider Extensions.

If successful the IUA Authorization Server SHALL generate an OAuth 2.1 authorization code and perform a callback to the URL defined in the request, using the OAuth authorization code as URL query parameter with key ‘code’.

The IUA Authorization Server SHALL store the access token and the assigned authorization code and respond the access token on request to the Authorization Client.

⁴This covers all possible EPR transaction, with the exception of the ITI-103
⁵The XUA Authentication Provider currently only supports SAML 2 based authentication as defined in Annex 8 of the EPDV-EDI, but will be extended to Open ID Connect in the future. Currently SMART on FHIR does not have a SAML 2 option.

Message Example

Request

The first step of the request conversion is a HTTP GET which may look like for a basic access token:

GET authorize?
    response_type=code&
    client_id=app-client-id&
    http%3A%2F%2Flocalhost%3A9000%2Fcallback&
    launch=xyz123&
    scope=launch+user%2F%2A.%2A+openid+fhirUser&state=98wrghuwuogerg97&aud=https%3A%2F%2Fehr%2Ffhir&code_challenge=ZmVjMmIwMWYyYTNjZWJiNTgyNTgxYzlmOGYyMWM0MWI3YmZhMjQ4YjU5MDc3Mzk4MDBmYTk0OThlNzZiNjAwMw&code_challenge_method=S256 HTTP/1.1

Host: localhost:9001

for an extended access token where at least purpose_of_use (NORM), subject_role (HCP) and person_id are added to the scope:

GET authorize?
    response_type=code&
    client_id=app-client-id&
    http%3A%2F%2Flocalhost%3A9000%2Fcallback&
    launch=xyz123&
    scope=launch+user%2F*.*+openid+fhirUser+purpose_of_use%3Durn%3Aoid%3A2.16.756.5.30.1.127.3.10.5%7CNORM+subject_role%3Durn%3Aoid%3A2.16.756.5.30.1.127.3.10.6%7CHCP+person_id%3D761337610411353650%5E%5E%5E%26amp%3B2.16.756.5.30.1.127.3.10.3%26amp%3BISO%0A&code_challenge=ZmVjMmIwMWYyYTNjZWJiNTgyNTgxYzlmOGYyMWM0MWI3YmZhMjQ4YjU5MDc3Mzk4MDBmYTk0OThlNzZiNjAwMw&code_challenge_method=S256 HTTP/1.1

Host: localhost:9001

The second step of the request conversion is a HTTP GET Callback conveying the authorization code and may look like:

GET /callback?code=8V1pr0rJ&state=98wrghuwuogerg97 HTTP/1.1 

Host: localhost:9000

The third step of the request conversion is a HTTP POST sending the authorization code to retrieve the authorization token in the response which may look like:

POST /token HTTP/1.1 
Host: localhost:9001

Accept: application/json
Content-type: application/x-www-form-encoded
Authorization: Basic bXktYXBwOm15LWFwcC1zZWNyZXQtMTIz
grant_type=authorization_code&redirect_uri=http%3A%2F%2Flocalhost%3A9000%2Fcallback&code=98wrghuwuogerg97&code_verifier=qskt4342of74bkncmicdpv2qd143iqd822j41q2gupc5n3o6f1clxhpd2x11

Response

A JWT access token returned by the IUA Authorization Server and to be used to retrieve patient data may look like:

{
  "iss": "http://issuerAdress.ch",
  "sub": "UserId-bfe8a208-b9d0-4012-b2f5-168b949fc3cb",
  "aud": "http://pixmResourceServerURL.ch",
  "exp": 1587294580000,
  "nbf": 1587294460000,
  "iat": 1587294460000,
  "jti": "c5436729-3f26-4dbf-abd3-2790dc7771a",
  "extensions" : {  
    "ihe_iua" : {  
      "subject_name": "Martina Musterarzt"
    }, 
    "ch_epr": {
      "user_id": "2000000090092", 
      "user_id_qualifier": "urn:gs1:gln" 
    }
}

A extend JWT access token to be used to access patient documents SHALL have the additional attributes of the purpose of use, subject role, the EPR-SPID of the patient and may look like:

{
  "iss": "http://issuerAdress.ch",
  "sub": "UserId-bfe8a208-b9d0-4012-b2f5-168b949fc3cb",
  "aud": "http://mhdResourceServerURL.ch",
  "exp": 1587294580000,
  "nbf": 1587294460000,
  "iat": 1587294460000,
  "jti": "c5436729-3f26-4dbf-abd3-2790dc7771a",
  "extensions" : {  
    "ihe_iua" : {  
      "subject_name": "Martina Musterarzt",
      "person_id": "761337610411353650^^^&2.16.756.5.30.1.127.3.10.3&ISO",
      "subject_role": {
          "system": "urn:oid:2.16.756.5.30.1.127.3.10.6",
          "code": "HCP"
      },
      "purpose_of_use": {
          "system": "urn:uuid:2.16.756.5.30.1.127.3.10.5",
          "code": "NORM",
      }
    }, 
    "ch_epr": {
      "user_id": "2000000090092", 
      "user_id_qualifier": "urn:gs1:gln" 
    },
    "ch_group" : [
      {
        "name": "Name of group with id urn:oid:2.2.2.1",
        "id": "urn:oid:2.2.2.1"
      }, 
      {
        "name": "Name of group with id urn:oid:2.2.2.2",
        "id": "urn:oid:2.2.2.2"
      },
      {
        "name": "Name of group with id urn:oid:2.2.2.2",
        "id": "urn:oid:2.2.2.3"
      }
    ]
  }
}

A JWT access token to be used to access by an assistant acting behalf on a healthcare professional for a patient SHALL have the additional extension ch_delegation:

{
  "iss": "http://issuerAdress.ch",
  "sub": "UserId-bfe8a208-b9d0-4012-b2f5-168b949fc3cb",
  "aud": "http://mhdResourceServerURL.ch",
  "exp": 1587294580000,
  "nbf": 1587294460000,
  "iat": 1587294460000,
  "jti": "c5436729-3f26-4dbf-abd3-2790dc7771a",
  "extensions" : {  
    "ihe_iua" : {  
      "subject_name": "Dagmar Musterassistent",
      "person_id": "761337610411353650^^^&2.16.756.5.30.1.127.3.10.3&ISO",
      "subject_role": {
          "system": "urn:oid:2.16.756.5.30.1.127.3.10.6",
          "code": "HCP"
      },
      "purpose_of_use": {
          "system": "urn:uuid:2.16.756.5.30.1.127.3.10.5",
          "code": "NORM",
      }
    }, 
    "ch_epr": {
      "user_id": "2000000090108", 
      "user_id_qualifier": "urn:gs1:gln" 
    }, 
    "ch_group" : [
      {
        "name": "Name of group with id urn:oid:2.2.2.1",
        "id": "urn:oid:2.2.2.1"
      }, 
      {
        "name": "Name of group with id urn:oid:2.2.2.2",
        "id": "urn:oid:2.2.2.2"
      },
      {
        "name": "Name of group with id urn:oid:2.2.2.2",
        "id": "urn:oid:2.2.2.3"
      }
    ],
    "ch_delegation": {
      "principal": "Martina Musterarzt", 
      "principal_id": "2000000090092" 
    }
  }
}

Security Consideration

As specified in the IUA profile, the IUA Authorization Client and Authorization Server actors SHALL support the JWS (signed) alternative of the JWT token. Any actor that supports this transaction MAY support the JWE (unsigned but encrypted) alternative of the JWT token.