Spring Security by example: OpenID (login via gmail)

This is a part of a simple Spring Security tutorial: 1. Set up and form authentication 2. User in the backend (getting logged user, authentication, testing) 3. Securing web resources 4. Securing methods 5. OpenID (login via gmail) 6. OAuth2 (login v…This is a part of a simple Spring Security tutorial: 1. Set up and form authentication 2. User in the backend (getting logged user, authentication, testing) 3. Securing web resources 4. Securing methods 5. OpenID (login via gmail) 6. OAuth2 (login v…

This is a part of a simple Spring Security tutorial:

1. Set up and form authentication 

2. User in the backend (getting logged user, authentication, testing)

3. Securing web resources

4. Securing methods

5. OpenID (login via gmail)

6. OAuth2 (login via Facebook)

7. Writing on Facebook wall with Spring Social

OpenID is to form authentication, what DVCS is to centralized version control system.

Ok, but without the technical mumbo-jumbo: OpenID allows the user to use one account (like Gmail) to login to other services (websites) without having to remember anything and without worries about password security.

Easy enough?

And the best part is: chances are, you already have an account which is a provider to OpenID. Are you registered on Gmail, Yahoo, or even Blogger? You can already use it to login to other sites.

But why would you? Isn’t login/password good enough?

Have you ever wondered whether the service you are logging to, uses one-way password hashing or keeps the password as open text? Most users do not create password per site because they cannot remember more than, let’s say, three passwords. If one site keeps their password as open text, they are practically screwed. And more often than not, it’s the site that has the worst (or non-existing) security. Welcome to hell: all your bases are belong to us.

By the way, I know of only one site, which does SHA hashing on the client side (in javascript), so that the server has no way of knowing what the real password is: sprezentuj.pl

Kudos for that, though it smells like overengineering a bit :)

OpenID is pretty simple, and the process description at Wikipedia is practically everything you need, but as they say, one picture is worth 1000 words, so let’s look at a  picture. There is a loot you can find with google, but most of them are in big-arrows-pointing-some-boxes-notation, and I find easier to read a sequence diagram, so here is my take on it:

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JBoss Envers and Spring transaction managers

I've stumbled upon a bug with my configuration for JBoss Envers today, despite having integration tests all over the application. I have to admit, it casted a dark shadow of doubt about the value of all the tests for a moment. I've been practicing TDD since 2005, and frankly speaking, I should have been smarter than that.

My fault was simple. I've started using Envers the right way, with exploratory tests and a prototype. Then I've deleted the prototype and created some integration tests using in-memory H2 that looked more or less like this example:

@Test
public void savingAndUpdatingPersonShouldCreateTwoHistoricalVersions() {
    //given
    Person person = createAndSavePerson();
    String oldFirstName = person.getFirstName();
    String newFirstName = oldFirstName + "NEW";

    //when
    updatePersonWithNewName(person, newFirstName);

    //then
    verifyTwoHistoricalVersionsWereSaved(oldFirstName, newFirstName);
}

private Person createAndSavePerson() {
    Transaction transaction = session.beginTransaction();
    Person person = PersonFactory.createPerson();
    session.save(person);
    transaction.commit();
    return person;
}    

private void updatePersonWithNewName(Person person, String newName) {
    Transaction transaction = session.beginTransaction();
    person.setFirstName(newName);
    session.update(person);
    transaction.commit();
}

private void verifyTwoHistoricalVersionsWereSaved(String oldFirstName, String newFirstName) {
    List<Object[]> personRevisions = getPersonRevisions();
    assertEquals(2, personRevisions.size());
    assertEquals(oldFirstName, ((Person)personRevisions.get(0)[0]).getFirstName());
    assertEquals(newFirstName, ((Person)personRevisions.get(1)[0]).getFirstName());
}

private List<Object[]> getPersonRevisions() {
    Transaction transaction = session.beginTransaction();
    AuditReader auditReader = AuditReaderFactory.get(session);
    List<Object[]> personRevisions = auditReader.createQuery()
            .forRevisionsOfEntity(Person.class, false, true)
            .getResultList();
    transaction.commit();
    return personRevisions;
}

Because Envers inserts audit data when the transaction is commited (in a new temporary session), I thought I have to create and commit the transaction manually. And that is true to some point.

My fault was that I didn't have an end-to-end integration/acceptance test, that would call to entry point of the application (in this case a service which is called by GWT via RPC), because then I'd notice, that the Spring @Transactional annotation, and calling transaction.commit() are two, very different things.

Spring @Transactional annotation will use a transaction manager configured for the application. Envers on the other hand is used by subscribing a listener to hibernate's SessionFactory like this:

<bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean" >        
...
 <property name="eventListeners">
     <map key-type="java.lang.String" value-type="org.hibernate.event.EventListeners">
         <entry key="post-insert" value-ref="auditEventListener"/>
         <entry key="post-update" value-ref="auditEventListener"/>
         <entry key="post-delete" value-ref="auditEventListener"/>
         <entry key="pre-collection-update" value-ref="auditEventListener"/>
         <entry key="pre-collection-remove" value-ref="auditEventListener"/>
         <entry key="post-collection-recreate" value-ref="auditEventListener"/>
     </map>
 </property>
</bean>

<bean id="auditEventListener" class="org.hibernate.envers.event.AuditEventListener" />

Envers creates and collects something called AuditWorkUnits whenever you update/delete/insert audited entities, but audit tables are not populated until something calls AuditProcess.beforeCompletion, which makes sense. If you are using org.hibernate.transaction.JDBCTransaction manually, this is called on commit() when notifying all subscribed javax.transaction.Synchronization objects (and enver's AuditProcess is one of them).

The problem was, that I used a wrong transaction manager.

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" >
    <property name="dataSource" ref="dataSource"/>
</bean>

This transaction manager doesn't know anything about hibernate and doesn't use org.hibernate.transaction.JDBCTransaction. While Synchronization is an interface from javax.transaction package, DataSourceTransactionManager doesn't use it (maybe because of simplicity, I didn't dig deep enough in org.springframework.jdbc.datasource), and thus Envers works fine except not pushing the data to the database.

Which is the whole point of using Envers.

Use right tools for the task, they say. The whole problem is solved by using a transaction manager that is well aware of hibernate underneath.

<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager" >
    <property name="sessionFactory" ref="sessionFactory"/>
</bean>

Lesson learned: always make sure your acceptance tests are testing the right thing. If there is a doubt about the value of your tests, you just don't have enough of them,