SAP HANA Cloud, JWT Provider, and Certificate Collections

Hands-On Video Tutorial

Philip MUGGLESTONE just added another video tutorial to the SAP HANA Cloud series. In this blog, you will find the video embedded with some additional information and resources. Following along in the patented zero-to-hero format, you will be able to fix the dreaded HTTP 500 internal server error-type errors.

You can watch the video tutorial in a little over 5 minutes. What you learn is

• How to cause and solve a 500 internal server error
• How to create a JWT Provider and Certificate Collection using SQL

As we know your time is precious, you can find the code snippet on our GitHub repository

• github.com/saphanaacademy/SAPHANACloud/blob/master/trust.txt

500 Internal Server Error

When you want to pass on the credentials of the business user (as defined with the identity provider, e.g. SAP ID Service or Microsoft Azure AD) from the business logic application to the database, you need to manually configure the trust between the authorization server (XSUAA) and the resource server (SAP HANA Cloud).

Configure JWT Trust (using SQL)

In this video tutorial, Philip Mugglestone shows how to configure JWT trust between SAP HANA Cloud and the SAP Cloud Platform subaccount where an application has been deployed.

Without this trust, the application returns error message:

the predefined session variable cannot be set via SET command: 
XS_APPLICATIONUSER

0:00​ – Introduction and use case

1:20​ – Paste code snippet into SQL Console of SAP HANA Database Explorer

1:55​ – Query JWT provider(s), certificate(s), and certificate collection(s) a.k.a. PSE

2:30​ – Get authentication URL

2:45​ – Use API endpoint replacing ‘api’ with ‘subaccount’ and ‘cf’ with ‘authentication’, appending /sap/trust

3:20​ – Copy certificate and issuer and create the certificate and JWT Provider 

3:50​ – Create certificate collection and set purpose to JWT. 

Configure JWT Trust using SAP HANA Cockpit

Alternatively, we can also use the SAP HANA cockpit to configure the JWT trust, as shown in the next video. This video is part of the role attributes series.

• Blog

0:00​ – Introduction and use case

0:50​ – Role collections with attributes (documentation)

2:00​ – Prerequisite: SAP HANA Cloud 

2:30​ – XSUAA service

2:45​ – Prerequisite: Configure JWT Trust 

4:25​ – Import certificate

4:35​ – Create JWT Identity Provider

5:10​ – Create certificate collection (PSE)

5:45​ – Configure SAP Business Application Studio

6:20​ – Git clone sample code from github.com/saphanaacademy/scpapps

6:40​ – Showcase myapphana MTA (multi-target application)

7:10​ – Recap

SAP HANA Cloud and XSUAA

Ready-Made Authentication Strategy

With a few lines of code, you can plug a ready-made authentication strategy into your business logic application using xssec and xsenv; two Node.js packages provided by SAP.

The first section  implements the ready-made with a simple copy/paste of the code snippet. As documented,

• @sap/xssec: XS Advanced Container Security API for node.js

// XS Advanced Container Security API for node.js
const xsenv = require('@sap/xsenv');
xsenv.loadEnv();
const services = xsenv.getServices({uaa: { tag: 'xsuaa' }, hana: { tag: 'hana' }});
const xssec = require('@sap/xssec');
const passport = require('passport');
passport.use('JWT', new xssec.JWTStrategy(services.uaa));
app.use(passport.initialize());
app.use(passport.authenticate('JWT', {session: false}));

Using another convenience package, we can establish a connection to the SAP HANA Cloud instance without hardcoding any credentials, simply by passing environment variables (VCAP_SERVICES)

• @sap/hdbext

// HANA Client Utility
const hdbext = require('@sap/hdbext');
app.use(hdbext.middleware(services.hana));

This enables us to run a database query for authenticated and appropriately authorised users only, in this case those with the Admin scope.

app.get('/srv/db', function (req, res) {
if (req.authInfo.checkScope('$XSAPPNAME.Admin')) {
  req.db.exec('SELECT * FROM M_DATABASE', function (err, results) {
    if (err) 
      {res.type('text/plain').status(500).send('ERROR: ' + err.toString()); return;}
      res.status(200).json(results);});} 
    else 
      {res.status(403).send('Forbidden');}});

For more information about how this works exactly, see

• Authorization using XSUAA | Migrating from the Neo Environment to the Multi-Cloud Foundation

One More Thing

Unfortunately, as ready-made as it is, the implementation requires an additional configuration to avoid HTTP 500 internal server error-type errors.

In OAuth terminology, this concerns the trust between the authorization server (XSUAA) and the resource server (SAP HANA Cloud).

PSE With Purpose JWT

For this trust to be established we need to import the certificate of the authorisation server into a Personal Security Environment (PSE) also known as a Certificate Collection.

Get Certificate

To obtain the certificate access the URL: tenant-id + uaadomain + endpoint

• 123abctrial +
• authentication +
• eu10.hana.ondemand.com +
• /sap/trust/jwt

For example

• https://8e3c745atrial.authentication.eu10.hana.ondemand.com/sap/trust/jwt

The URL returns Issuer and subject distinguished name (dn), purpose, public certificate, and issuer.

The figure shows the JSON key:values returned in a Chrome browser with JSON Viewer extension.

When in doubt, the parameters “url” and “uaadomain” are accessible as environment variables (VCAP_SERVICES) when you bind an XSUAA service instance to an application.

Create JWT Provider

Add an identity provider using the JWT Identity Provider app of the SAP HANA Cockpit. Use the value of issuer with claim user_name. The name must start with a letter and contain only ASCII characters, digits, and underscores.

Alternatively, use SQL statement CREATE JWT PROVIDER with the certificate in single quotes.

CREATE JWT PROVIDER XSUAA_IDP WITH ISSUER 'https://8e3c745atrial.authentication.eu10.hana.ondemand.com/oauth/token' 
CLAIM 'user_name' AS EXTERNAL IDENTITY;

Import Certificate

Import the certificate using the Certificate Store app of the SAP HANA Cockpit.

Alternatively, use SQL statement CREATE CERTIFICATE with the certificate in single quotes.

CREATE certificate FROM 
'-----BEGIN CERTIFICATE-----<string>-----END CERTIFICATE-----';

Create Certificate Collection

Create a certificate collection, add the certificate, and set the purpose to JWT.

Alternatively, use SQL statement CREATE PSE, add the certificate using ALTER PSE and set the purpose to JWT.

CREATE PSE XSUAA;
SELECT * from CERTIFICATES;
ALTER PSE XSUAA ADD certificate <certificate-id>;
SET PSE XSUAA PURPOSE JWT FOR PROVIDER XSUAA_IDP;

As documented

• Single Sign-On Using JSON Web Tokens | SAP HANA Cloud Security Guide
• Certificate Collections | SAP HANA Cloud Security Guide

Share and Connect

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Thanks!

If you would like to receive updates, connect with me on

• LinkedIn > linkedin.com/in/dvankempen
• Twitter > @dvankempen

For the author page of SAP PRESS, visit

• Denys van Kempen

For the SAP HANA Cloud e-bite, see

• Introducing SAP HANA Cloud