Cross-domain single sign-on with the ForgeRock Identity Cloud

For organizations relying on AM’s session and policy services with SSO, consider cross-Domain Single Sign-On (CDSSO) as an alternative to SSO through OpenID Connect.

This example sets up ForgeRock Identity Cloud as an SSO authentication server for requests processed by Identity Gateway. For more information about about Identity Gateway and CDSSO, see Authenticate With CDSSO.

Before you start, prepare Identity Cloud, IG, and the sample application as described in Example installation for this guide.

Set up Identity Cloud:
1. Log in to Identity Cloud as an administrator.
2. Make sure that you are managing the alpha realm. If not, click the current realm at the top of the screen, and switch realm.
3. Go to group Identities > Manage > settings_system_daydream Alpha realm - Users, and add a user with the following values:
  - Username: demo
  - First name: demo
  - Last name: user
  - Email Address: demo@example.com
  - Password: Ch4ng3!t
4. Click verified_user Gateways & Agents, and add an IG agent with the following values:
  - ID: ig_agent_cdsso
  - Password: password
  - Redirect URLs: https://ig.ext.com:8443/home/cdsso/redirect
5. Select Services > Add a Service, and add a Validation Service with the following Valid goto URL Resources:
  - https://ig.ext.com:8443/*
  - https://ig.ext.com:8443/*?*

Set up Identity Gateway:

Set up IG for HTTPS, as described in Configure IG for HTTPS (server-side) in standalone mode.
Add the following session configuration to admin.json, to ensure that the browser passes the session cookie in the form-POST to the redirect endpoint (step 6 of Information Flow During CDSSO):
```
{
  "connectors": […],
  "session": {
    "cookie": {
      "sameSite": "none",
      "secure": true
    }
  },
  "heap": […]
}
```
This step is required for the following reasons:
- When sameSite is strict or lax, the browser does not send the session cookie, which contains the nonce used in validation. If IG doesn’t find the nonce, it assumes that the authentication failed.
- When secure is false, the browser is likely to reject the session cookie.
  
  For more information, see admin.json.
Set an environment variable for the IG agent password, and then restart IG:
```
$ export AGENT_SECRET_ID='cGFzc3dvcmQ='
```
The password is retrieved by a SystemAndEnvSecretStore, and must be base64-encoded.

Add the following route to IG, to serve .css and other static resources for the sample application:

Linux
Windows

$HOME/.openig/config/routes/static-resources.json

%appdata%\OpenIG\config\routes\static-resources.json

{
  "name" : "sampleapp-resources",
  "baseURI" : "http://app.example.com:8081",
  "condition": "${find(request.uri.path,'^/css')}",
  "handler": "ReverseProxyHandler"
}

Add the following route to Identity Gateway, replacing the value for the property amInstanceUrl:

Linux
Windows

$HOME/.openig/config/routes/cdsso-idc.json

%appdata%\OpenIG\config\routes\cdsso-idc.json

{
  "name": "cdsso-idc",
  "baseURI": "http://app.example.com:8081",
  "condition": "${find(request.uri.path, '^/home/cdsso')}",
  "properties": {
    "amInstanceUrl": "https://myTenant.forgeblocks.com/am"
  },
  "heap": [
    {
      "name": "SystemAndEnvSecretStore-1",
      "type": "SystemAndEnvSecretStore"
    },
    {
      "name": "AmService-1",
      "type": "AmService",
      "config": {
        "url": "&{amInstanceUrl}",
        "realm": "/alpha",
        "version": "7.2",
        "agent": {
          "username": "ig_agent_cdsso",
          "passwordSecretId": "agent.secret.id"
        },
        "secretsProvider": "SystemAndEnvSecretStore-1",
        "sessionCache": {
          "enabled": false
        }
      }
    }
  ],
  "handler": {
    "type": "Chain",
    "config": {
      "filters": [
        {
          "name": "CrossDomainSingleSignOnFilter-1",
          "type": "CrossDomainSingleSignOnFilter",
          "config": {
            "redirectEndpoint": "/home/cdsso/redirect",
            "authCookie": {
              "path": "/home",
              "name": "ig-token-cookie"
            },
            "amService": "AmService-1",
            "verificationSecretId": "verify",
            "secretsProvider": {
              "type": "JwkSetSecretStore",
              "config": {
                "jwkUrl": "&{amInstanceUrl}/oauth2/realms/alpha/connect/jwk_uri"
              }
            }
          }
        }
      ],
      "handler": "ReverseProxyHandler"
    }
  }
}

Notice the following features of the route compared to cdsso.json in CDSSO for IG in standalone mode, where Access Management is running locally:

The AmService URL points to Access Management in the Identity Cloud.
The AmService realm points to the realm where you configure your IG agent.

Test the setup:
1. Go to https://ig.ext.com:8443/home/cdsso.
  
  If you see warnings that the site is not secure, respond to the warnings to access the site.
  
  The Identity Cloud login page is displayed.
2. Log in to Identity Cloud as user demo, password Ch4ng3!t.
  
  Access Management calls /home/cdsso/redirect, and includes the CDSSO token. The CrossDomainSingleSignOnFilter passes the request to sample app.