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identity-facade

README.md

Identity Facade

An identity facade that is used in front of an OpenID Connect (OIDC) compliant Identity Provider (IdP). The aim of the identity facade is to deal with all the interactions between a client app and an IdP and to generate an OAuth 2.0 access token that can be used by the client app to access protected resources through Apigee.

This reference promotes a clear separation of concerns between Apigee and the IdP.

  • Apigee is responsible for authenticating client apps
  • The IdP is in charge of authenticating the end-users

The IdP that is used is the OIDC Mock IdP but you may use any OIDC compliant IdP. Should you use your own IdP solution, please provide the following environment variables to the pipeline.sh script:

  • IDP_DISCOVERY_DOCUMENT: this variable MUST point to the URL of the discovery document of your IdP solution.
  • TEST_IDP_APIGEE_CLIENT_ID: the client_id Apigee can use to connect to the IdP
  • TEST_IDP_APIGEE_CLIENT_SECRET: the client_secret Apigee can use to connect to the IdP

Anti-forgery State Token

In order to protect against Cross-Site Request Forgery (CSRF) attacks, it is strongly recommended that API consumers include the state parameter in requests to the /authorize endpoint.

As stated in the OAuth 2 specification, the state parameter is "An opaque value used by the client to maintain state between the request and callback. The authorization server includes this value when redirecting the user-agent back to the client.".

Applications should generate a random string and use it as a state value. After the /authorize request is sent, the user is redirected back to the application, and the state value will be included in this redirect. Applications compare this returned value with the random string generated earlier, and if the values match, approve the authentication response, else they need to deny it.

PKCE: Proof Key for Code Exchange

The identity facade can be configured to implement PKCE.

PKCE is used to mitigate against authorization code interception attack. The PKCE code challenge method used in the identity facade reference is set to S256.

If you want the identity facade to implement PKCE then it is necessary to set the environment variable IS_PKCE_ENABLED to the value true.

export IS_PKCE_ENABLED=true

In the other cases the value of this variable is considered to be false. The default value of the variable IS_PKCE_ENABLED is also set to false.

Dependencies

Quick start

Apigee X / hybrid

export APIGEE_X_ORG=xxx
export APIGEE_X_ENV=xxx
export APIGEE_X_HOSTNAME=api.example.com

./pipeline.sh --googleapi

Apigee Edge

export APIGEE_ORG=xxx
export APIGEE_ENV=xxx
export APIGEE_USER=xxx
export APIGEE_PASS=xxx

./pipeline.sh --apigeeapi

Script outputs

The pipeline script deploys on Apigee an API Proxy containing the full configuration of the identity facade reference as well as the following elements:

  • the OIDC Mock IdP reference
  • A Key Value Map (idpConfigIdentityProxy) with values inherited from the IdP's discovery document. This KVM is scoped at env level.
  • A cache (IDP_JWKS_CACHE) used to cache JWKS keys received from the IdP. This cache is scoped at env level.
  • An API Product only used for functional tests
  • A developer app only used for functional tests

On the machine and directory from where the script is executed, you can find a edge.json file, which contains the configuration of all these elements.

Finally, the pipeline script provides the authorization URL that you can copy/paste into your favorite web browser to initiate the OIDC flow.

Identity Facade Sequence Diagram

The sequence diagram providing all the interactions between end-user, web-browser, client app, Apigee (identity facade and data proxy), IdP and backend is available as a text file If needed, you can modify this file and re-generate the related picture (png) using the following command:

./generate_docs.sh

Here is the original sequence diagram:

Identity Facade

Query and form parameters as well as proxy processing specific to PKCE are indicated in blue on the sequence diagram.

Identity Facade Endpoints

Available endpoints are the following ones:

  1. GET /authorize: to deal with the initiation of the authentication sequence
  2. GET /callback: to deal with access token issuance
  3. POST /token: to deal with access token issuance
  4. GET /protected: to simulate access to a protected resource