SMART App Launch
2.0.0 - Release

SMART App Launch, published by HL7 International - FHIR Infrastructure WG. This is not an authorized publication; it is the continuous build for version 2.0.0). This version is based on the current content of https://github.com/HL7/smart-app-launch/ and changes regularly. See the Directory of published versions

Worked Example Id Token

Working with SMART on FHIR ID Tokens (examples)

# !pip3 install python-jose
from Crypto.PublicKey import RSA
import json
import jose.jwk
import jose.jwt
import jose.constants

Setup

To create self-contained example, we’ll generate a new RSA Key for a fake organization called “my-ehr.org”, and we’ll use that for the operations below.

key = RSA.generate(2048)

private = key.exportKey('PEM').decode()
public = key.publickey().exportKey().decode()
print(public, "\n\n", private)
-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAqgr+Ee4zvGP+giYxCAJ1
oI/ZIwhnUueEyVGqXgWJKqTUkliL9ccK0lsaPKDPUlGeIhyjJJQKjOfWWS5bMucs
x3h9t4x98aZVkYUAdm7RSwjd3b59Fr6G60SsfrbtYhp4varKk2ZP2Ex2lB6ZHZoc
3hFs/sMKibQNGqQT2bt+xpHvGtY994Tun/C3iOvjk3hvHMDp5Q+NY0aE/FURLEsa
quBbOam0JTf9XVY8SBIsKb9sV0F6/lvWXos/acZflIFUyf22Z6eKniJKlH4FhrsQ
c8YeILGR3iEKY3vauajCjHJkAyR+/fNKdRO0gQI12DxAL+piA8XtDxodNeTmIDXM
rwIDAQAB
-----END PUBLIC KEY-----

 -----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

Creating an ID Token (for servers)

Servers will create a signed JWT by following a process like this.

Create a set of claims

These should include:

  • sub: the user
  • aud: the app for whom this ID Token is being produced
  • iss: an identifier for this EHR system)
  • profile: the absolute URL of the FHIR resource representing the current user

Encode them in a JWT

Signing with the server’s private key

claims = {
  "sub": "alice",
  "aud": "growth-chart-app-123",
  "iss": "https://my-ehr.org/fhir",
  "fhirUser": "https://my-ehr.org/fhir/Practitioner/123"
}


id_token = jose.jwt.encode(
    claims,
    key,
    algorithm='RS384')

print(id_token)
eyJ0eXAiOiJKV1QiLCJhbGciOiJSUzM4NCJ9.eyJzdWIiOiJhbGljZSIsImF1ZCI6Imdyb3d0aC1jaGFydC1hcHAtMTIzIiwiaXNzIjoiaHR0cHM6Ly9teS1laHIub3JnL2ZoaXIiLCJmaGlyVXNlciI6Imh0dHBzOi8vbXktZWhyLm9yZy9maGlyL1ByYWN0aXRpb25lci8xMjMifQ.BuivDG9lOu0mI5ESm2Cl4EoGTW0BFA3N5oPcEX30Q77vxBuMspRd9N6kKLgTj8TsAFAutXKlTztdbbyDsTVcjYRZervUMgfS5gv2ERmTTy6wnWRxcsxA8oCmwJ8nqIz9VztCd73IZ8zvCebnaIwTjqt3r5a1aWNqRftncUa5pA2nN3DezMPrWaQ6U_S-QcyVrS_NznqRzI_2JFXlnLn6xSD6CXAfSHRy-1M2VZA4b6m6K3LXM2Pe_WF8HJ1GCLKLMqvYM0oQGLgy4tpDrDr8T8kxd4nLisIjQoXVjx5kASSaSiEuPYMG5E0h9eeSUZFVG-FvYtkgXF3vKaBJjX40BA

Validating and using an ID Token (for clients)

A client obtains the ID Token as the result of an authorization operation. To validate the token, the client fetches the servers’s public key, and then decodes the token. While decoding the token, the client must verify that the audience (‘aud’) matches its own client_id

jose.jwt.decode(id_token, public, audience='growth-chart-app-123')
{'sub': 'alice',
 'aud': 'growth-chart-app-123',
 'iss': 'https://my-ehr.org/fhir',
 'fhirUser': 'https://my-ehr.org/fhir/Practitioner/123'}