How to handle authentication in a RESTful Client-Server architecture is a matter of debate.
Commonly, it can be achieved, in the SOA over HTTP world via:
- HTTP basic auth over HTTPS;
- Cookies and session management;
- Token in HTTP headers (e.g. OAuth 2.0 + JWT);
- Query Authentication with additional signature parameters.
You'll have to adapt, or even better mix those techniques, to match your software architecture at best.
Each authentication scheme has its own PROs and CONs, depending on the purpose of your security policy and software architecture.
HTTP basic auth over HTTPS
This first solution, based on the standard HTTPS protocol, is used by most web services.
GET /spec.html HTTP/1.1
Host: www.example.org
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
It's easy to implement, available by default on all browsers, but has some known drawbacks, like the awful authentication window displayed on the Browser, which will persist (there is no LogOut-like feature here), some server-side additional CPU consumption, and the fact that the user-name and password are transmitted (over HTTPS) into the Server (it should be more secure to let the password stay only on the client side, during keyboard entry, and be stored as secure hash on the Server).
We may use Digest Authentication, but it requires also HTTPS, since it is vulnerable to MiM or Replay attacks, and is specific to HTTP.
Session via Cookies
To be honest, a session managed on the Server is not truly Stateless.
One possibility could be to maintain all data within the cookie content. And, by design, the cookie is handled on the Server side (Client, in fact, does even not try to interpret this cookie data: it just hands it back to the server on each successive request). But this cookie data is application state data, so the client should manage it, not the server, in a pure Stateless world.
GET /spec.html HTTP/1.1
Host: www.example.org
Cookie: theme=light; sessionToken=abc123
The cookie technique itself is HTTP-linked, so it's not truly RESTful, which should be protocol-independent, IMHO. It is vulnerable to MiM or Replay attacks.
Granted via Token (OAuth2)
An alternative is to put a token within the HTTP headers so that the request is authenticated. This is what OAuth 2.0 does, for instance. See the RFC 6749:
GET /resource/1 HTTP/1.1
Host: example.com
Authorization: Bearer mF_9.B5f-4.1JqM
In short, this is very similar to a cookie and suffers to the same issues: not stateless, relying on HTTP transmission details, and subject to a lot of security weaknesses - including MiM and Replay - so is to be used only over HTTPS. Typically, a JWT is used as a token.
Query Authentication
Query Authentication consists in signing each RESTful request via some additional parameters on the URI. See this reference article.
It was defined as such in this article:
All REST queries must be authenticated by signing the query parameters
sorted in lower-case, alphabetical order using the private credential
as the signing token. Signing should occur before URL encoding the
query string.
This technique is perhaps the more compatible with a Stateless architecture, and can also be implemented with a light session management (using in-memory sessions instead of DB persistence).
For instance, here is a generic URI sample from the link above:
GET /object?apiKey=Qwerty2010
should be transmitted as such:
GET /object?timestamp=1261496500&apiKey=Qwerty2010&signature=abcdef0123456789
The string being signed is /object?apikey=Qwerty2010×tamp=1261496500
and the signature is the SHA256 hash of that string using the private component of the API key.
Server-side data caching can be always available. For instance, in our framework, we cache the responses at the SQL level, not at the URI level. So adding this extra parameter doesn't break the cache mechanism.
See this article for some details about RESTful authentication in our client-server ORM/SOA/MVC framework, based on JSON and REST. Since we allow communication not only over HTTP/1.1, but also named pipes or GDI messages (locally), we tried to implement a truly RESTful authentication pattern, and not rely on HTTP specificity (like header or cookies).
Later Note: adding a signature in the URI can be seen as bad practice (since for instance it will appear in the http server logs) so it has to be mitigated, e.g. by a proper TTL to avoid replays. But if your http logs are compromised, you will certainly have bigger security problems.
In practice, the upcoming MAC Tokens Authentication for OAuth 2.0 may be a huge improvement in respect to the "Granted by Token" current scheme. But this is still a work in progress and is tied to HTTP transmission.
Conclusion
It's worth concluding that REST is not only HTTP-based, even if, in practice, it's also mostly implemented over HTTP. REST can use other communication layers. So a RESTful authentication is not just a synonym of HTTP authentication, whatever Google answers. It should even not use the HTTP mechanism at all but shall be abstracted from the communication layer. And if you use HTTP communication, thanks to the Let's Encrypt initiative there is no reason not to use proper HTTPS, which is required in addition to any authentication scheme.
If your authentication is already done using an SSO service, then you should use one of spring security's pre-authentication filters. Then you can specify a UserDetails service (possibly custom) that will use the pre-authenticated user principle to populate the GrantedAuthority's
SpringSecurity includes several pre-authentication filters including J2eePreAuthenticatedProcessingFilter and RequestHeaderPreAuthenticatedProcessingFilter. If you can't find one that works for you, its also possible, and not that hard to write your own, provided you know where in the request your SSO implementation stuffs the data. (That depends on the implementation of course.)
Just implement the Filter interface and do something like this in the doFilter method:
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// principal is set in here as a header or parameter. you need to find out
// what it's named to extract it
HttpServletRequest req = (HttpServletRequest) request;
if (SecurityContextHolder.getContext().getAuthentication() == null) {
// in here, get your principal, and populate the auth object with
// the right authorities
Authentication auth = doAuthentication(req);
SecurityContextHolder.getContext().setAuthentication(auth);
}
chain.doFilter(request, response);
}
Best Answer
Ok in the absence of an answer that gives a high level view of how all this hangs together I thought I'd scribble down my findings so far:
The company uses Active Directory to store user logon details, so as this is used for Membership I don't need a custom Membership provider. Once a user is logged on to the company network then they are authenticated. Adding a global Authorize filter ensures that any user accessing the system will need to be authenticated. Up to date info from Rick Anderson on msdn:
http://blogs.msdn.com/b/rickandy/archive/2012/03/23/securing-your-asp-net-mvc-4-app-and-the-new-allowanonymous-attribute.aspx
So in Global.asax I would add:
Once a user is authenticated I then need to take care of Authorization. The company have an existing global data store for roles that I won't have update access to, only read access, so I can retrieve the roles for a given user via a stored proc call. It can take from a few days to a couple of weeks for the helpdesk to create roles after a request is made, so for this reason 2 standard roles will be initially created, User and Admin, and subsequent roles will be stored in our application database.
Along with these 2 standard roles subsequent roles are required such as Superuser, etc. These roles will have various rights depending on business rules etc. and will need to be stored in our application database. So for this scenario I will need to create a custom Role provider, add the appropriate asp.net role tables to my app database, and plug it into the web.config. Here's an ms page titled Managing Authorization Using Roles that I'm picking bits out of:
http://msdn.microsoft.com/en-us/library/9ab2fxh0.aspx
From what I've read so far the only tables I need for a custom role provider are Roles and UsersInRoles.
CREATE TABLE Roles ( Rolename Text (255) NOT NULL, ApplicationName Text (255) NOT NULL, CONSTRAINT PKRoles PRIMARY KEY (Rolename, ApplicationName) )
CREATE TABLE UsersInRoles ( Username Text (255) NOT NULL, Rolename Text (255) NOT NULL, ApplicationName Text (255) NOT NULL, CONSTRAINT PKUsersInRoles PRIMARY KEY (Username, Rolename, ApplicationName) )
Once all this is setup I need to figure out how to merge the 2 standard roles (User and Admin) from the global data store with the custom roles stored in my app database, and if I can use (e.g.) [Authorize(Roles="Admin, Superuser")] on a Controller/Action or if I need to subclass AuthoriseAttribute and do something more clever.
I just realised that as I use AD for authentication I need a way of adding / injecting the collection of roles the current user is a member of. So although I don't need any custom membership provider functionality I still have to interact with httpContext.User to update its Roles collection.