Spring Security Salt

Question

I'm trying to add a salt when adding a new user/pwd, but the docs seem to be missing how to do this.

Here's a basic example:

<authentication-manager>
    <authentication-provider user-service-ref="userDetailsService">
        <password-encoder hash="md5">
            <salt-source user-property="username"/>
        </password-encoder>
    </authentication-provider>
</authentication-manager>

You can see by the example that neither a custom salt or custom password encoder is used.

So, how would I wire the Salt in when adding a new user/pwd? I'd assume it would be something along the lines of:

@Autowired SaltSource saltSource;
protected void foo(final CustomUser user) {
    final PasswordEncoder encoder = new Md5PasswordEncoder();
    user.setPassword(encoder.encodePassword(user.getPassword(), saltSource));
}

However, since I am using the default salt/password encoders and I don't have a custom salt bean the autowire would fail.

Any clue how to make this work?

Answer 1

You don't autowire the SaltSource when adding user. The SaltSource is an abstraction used by Spring to provide the source of the salt for password checking only.

To create a properly encoded password hash You just past the salt itself to the PasswordEncoder - the value of username property, not the SaltSource:

private PasswordEncoder encoder = new Md5PasswordEncoder();

public User createUser(String username, String plainTextPassword) {
    User u = new User();
    u.setUsername(username);
    u.setPassword(encoder.encodePassword(plainTextPassword, username));
    getEntityManager().persist(u); // optional
    return u;
}

---

Moreover the autowire of SaltSource won't work until it's defined as an inner bean. You could define the ReflectionSaltSource as top level bean and pass it's ID to the password-encoder, i.e.:

<bean id="saltSource"
    class="org.springframework.security.authentication.dao.ReflectionSaltSource"
    p:userPropertyToUse="username" />

<bean id="passwordEncoder" 
    class="org.springframework.security.authentication.encoding.Md5PasswordEncoder" />

<bean id="daoAuthenticationProvider"
    class="org.springframework.security.authentication.dao.DaoAuthenticationProvider"
    p:passwordEncoder-ref="passwordEncoder"
    p:saltSource-ref="saltSource"
    p:userDetailsService-ref="userDetailsService" />

<authentication-manager>
    <authentication-provider ref="daoAuthenticationProvider" />
</authentication-manager>

And then:

@Autowired private PasswordEncoder passwordEncoder;
@Autowired private SaltSource saltSource;

public CustomUserDetails createUser(String username, String plainTextPassword) {
    CustomUserDetails u = new CustomUserDetails();
    u.setUsername(username);
    u.setPassword(passwordEncoder.encodePassword(
            plainTextPassword, saltSource.getSalt(u)));
    getEntityNamager().persist(u); // optional
    return u;
}