I am attempting to make a website's back-end API (I want to make the back-end independent of the front-end so I'm only making a server-side API for now, abiding to RESTfulness as much as possible). I haven't done this before so I'm unaware of the 'best' & most secure way to do things.
How I do it now:
Some parts of the API should only be accessible to a specific user after they login and up to 24 hours later.
To do this, I am generating a random Session ID whenever a user logs in (I'm using passwordless logins so the user is assigned that ID when they click on a link in their email) on the server side, which respond by sending that session ID to the client once. The client then stores this session ID in localstorage (or a file in disk if the client is not a web browser).
Next, I store that ID along with the associated email in my DB (MySQL table) on the server side.
Now every time the client want something from my API, they have to provide the email & session ID in the URL (I don't want cookies for now), which the server checks against the ones in the DB, if they exist then the server responds fully else responds with an error.
After 24 hours, the server deletes the email/session ID pair and the user has to login again (to generate another session ID and associate it with their email).
Now the questions:
Is my method secure or does it have obvious vulnerabilities? Is
there another battle-tested way I'm not aware of?
Is there a better way for the client to store the session ID (if
they are a web browser)?
What is the best way to generate a unique session ID? Currently I
generate a random 16-char string that I set as the primary key of
the session-email table.
Is using a MySQL table the most performant/best way to store session
IDs (given it will be queried with each request)?
Do I need to encrypt session IDs in any way? Is it secure for the
client to send it as a 'naked' URL param?
Sorry for having too many questions in one post but I think they're related by the single scenario above. If it makes any difference, I'm using F# and I expect my client to either be an android app or a web app.
Your REST API MUST not know anything about the REST client session, not even the session id. If you don't want to send a password by every request, all you can do is signing the user id, and the timeout, so the service can authenticate based on the signature. Use JSON web token: https://en.wikipedia.org/wiki/JSON_Web_Token
You can have a server side REST client, which can have the session your described. The question is, does it really worth the effort to develop a REST service instead of a regular web application? I am not sure in your case, but typically the answer is no, because you won't have any 3rd party REST client and your application does not have enough traffic to justify the layered architecture or it is not big enough to split into multiple processes, etc...
If security is important then you MUST use a true random generator algorithm or hardware. https://en.wikipedia.org/wiki/Random_number_generation#.22True.22_vs._pseudo-random_numbers It is not safe to send anything through HTTP, you must use HTTPS instead. You MUST use the standard Authorization header instead of a query param. https://en.wikipedia.org/wiki/Basic_access_authentication
Related
I am at start of develoment of web-application. Application should be RESTful.
I am new to REST. And now I can't understand how user login/logout need to be done correctly to meet REST restrictions.
I spent good time to understand REST and already read many articles and answers on StackOverflow. Also I understand basic principle of "stateless" and it's benefits. So please no links on Wikipedia and basic sources about REST.
About task:
I have list of books in database on server. User who has login/password may come to site, enter login/password and view page with these books. So before to answer with list of books server need to be sure that user has rights to do it.
List of books will requested by AJAX call from browser.
I am going to make server to handle URL /books . When server receives GET request to this URL - it should
1) authenticate this call;
2) if OK - answer with list of books in JSON format.
As I understand so far - correct way of authentication for REST server is to authenticate each separate call. Client should use Secret Access Key and Access Key ID to encrypt query parameters. And server will check for Access Key ID, retrieve Secret Access Key (that is shared secret) and validate query in this way.
So server doesn't handle sessions because it violates "stateless" restriction of REST.
Only way how I see it could be done without sessions - use some Secret Access Key and Access Key ID to encrypt query parameters. This is how usual REST clients do. But there is a big difference between "normal" REST client and browser REST client.
Normal REST client (lets say it is standalone application or PHP-application on server) stores their Secret Access Key in some secure way. Nobody can see it. But JS application stores it right in code. And anybody can open this JS code and find this key.
So my question is:
How to organize authentication between browser (REST client) and server that handles REST API without exposing Secret Key to anybody who can open source code.
Or maybe I overestimate issue of storing of Secret Access Key in code?
I just see big difference with classical "stateful" application:
If I am logged in to some site and out of computer at the moment - nobody can come to computer and find my password in any place in memory of browser.
But with storing Secret Access Key in code it is possible.
Try to use the Basic authentication which works with browser based application. But problem with it is that it will always throw a pop-up to the user. An alternative to it is that you use a custom login header to do the authentication of each REST request, for example
headers : { "Authorization" : "customAuth" }
I'm currently trying to setup FOSOAuthServerBundle with my Symfony2 app.
Everything seems to be setup and functional, anyway I'm stuck after the installation.
What is the proper workflow with URLs to get the access_token ?
I tried /oauth/v2/auth, but sounds like I need to define a Client object first.
How to create/generate Client ? Clients are always supposed to be created manually ?
FOSOAuthServerBundle doc is great, but seems to skip all the usage workflow. Am I supposed to check the OAuth2 doc for this ?
Thanks !
In short, yes. You should be using the oAuth2 RFC to determine which workflow you want to use. In regards to client registration the RFC specifically states that the means through which a client registers is beyond the scope of the specification (https://www.rfc-editor.org/rfc/rfc6749#section-2).
With that being said I can give you some insight into how I did this. My application is a mobile phone application that connects to several services running on various servers. I'm also using the Resource Owner Password Credentials Grant.
The way I approached this was: when the application loads, the first thing it does is to check if it has an oAuth2 client id. If it doesn't, then it POSTS to a create client endpoint I've setted up with the meta-data I need. The endpoint validates the POST, creates the client and returns the client information. The application stores the client id and the process doesn't have to be repeated the next time.
Application loads;
Application checks for oAuth2 client id;
If there is one, the process ends;
If there isn't, it posts to http://www.example.com/client;
If we get a 200, store the oAuth2 client id.
I could have also created the oAuth2 client when the user created an account in the application, but I wanted to make the registration process as fast as possible. Creating the client would have added some extra waiting time to the process.
Check this: http://blog.logicexception.com/2012/04/securing-syfmony2-rest-service-wiith.html
It's quite simple to convert to Doctrine, whether you use it.
There's a command-line that does exactly what you need: create a Client!
I have seen many different posts regarding different solutions for authenticating a RESTful API and I have some questions, given this current scenario.
I've built a REST API that will allow clients of my software service (we are a B2B company) to access resources programmatically. Now that I've got the API working properly, I'd like to secure it in the most standardized way possible. I need to allow access to certain resources based on the caller of the API. That is to say, not all users of the API can access all resources.
I have URLS available in the following formats:
https://mydomain/api/students
https://mydomain/api/students/s123
https://mydomain/api/students/s123/classes
https://mydomain/api/students/s123/classes/c456
So far I've come up with these possible solutions:
Provide a unique key to each client that they can use to ultimately generate an encrypted token that will be passed as a GET parameter at the end of each REST call to (re)-authenticate every single request. Is this approach too expensive
https://mydomain.com/api/students/s123?token=abc123
Provide a value in the HTTP Authorization Header as seen here. Is this almost the same as #1? (Except I can't paste a URL into the browser) Do people use these headers anymore?
Use OAuth 2 (which I'm still a bit unclear on). Does OAuth 2 actually authenticate the client as a logged in user? And doesn't that go against the spirit of a REST API being stateless? I was hoping OAuth was the proper solution for me (since it's a public standard), but after reading up on it a little bit, I'm not so sure. Is it overkill and/or improper for REST API calls?
My goal is to provide an API that will not have to be changed for each client that wants to consume the API, but rather that I can provide a standard documentation made available to all of our clients.
I'll be happy to post additional details if I've been unclear.
There are 2 type of clients you probably want to prepare your API:
trusted clients - Which are written by you. They can have the username and password of the actual user, and they can send that data to your server with every request, possibly in a HTTP auth header. All you need is an encrypted connection by them.
3rd party clients - Which are written by some random developer. You can register them in your service and add a unique API key to each of them. After that if an user wants to use their services, you have to show her a prompt in which she can allow access to the 3rd party client. After that the 3rd party client will be assigned to the user's account with the given permissions and it will get an user specific access token. So when the client sends its API key and the user specific token along with the request, then it sends the requests in the name of the user.
OAuth can help you to control the second situation.
Your URLs do not have a meaning to the clients. By REST you have to decouple the clients from the URL structure by sending links annotated with semantics (e.g. link relations). So your documentation does not have to contain anything about the URL structure (maybe it can be useful for server side debug, but nothing more). You have to talk about different types of links. By generating these links on server side, you can check the permissions of the actual user (or 3rd party client) and skip the links which she does not have permission to follow.
We intend to develop rest based api. I explored the topic but it seems, you can secure api when your client is an app (So there are many ways, public key - private key etc). What about websites / mobile website, if we are accessing rest based api in website which do not use any login for accessing contents ( login would be optional ) then how could we restrict other people from accessing rest based api ?
Does it make sense using Oauth2.0 ? I don't have clear idea of that.
More clear question could be ,How can we secure get or post request exposed over web for the website which doesn't use any login ?
If it's simple get request or post request , which will return you json data on specific input, now i have mobile website , who will access those data using get request or post request to fetch data. Well, some else can also access it , problem is i am not using Login, user can access data directly. But how can we restrict other people from accessing that data.
What do you think is the difference between securing a website that is not using REST vs one that is using REST API?
OAuth provides authorisation capabilities for your site, in a REST architecture this means a user of the mobile application will have to provide their credentials before being allowed to access the resource. The application can then decide on if that user has access to the requested resource. However you've said your website doesn't need use authorisation.
You can use certificates however good luck managing the certificate for each client. My take on it is for your explanation you don't need to secure your website because you will never be able to manage a trust relationship between the client and the server. There are some options though:
You build your own client application that you ship out to people which can verify itself with the server using a packaged certificate with the client. E.g. iOS has this kind of feature if you build for that device.
You provide a capability to download a certificate that is 'installed' in the browser and used when communicating to your REST API
Use something like a handshaking protocol so when a client wants to make the first request it says; 'hi I'm a client can we chat?' And the server responds with 'yes for the next X minutes we can however make sure you send me this key everytime you tell me something YYYYYY' (you can use something like SecureUDID or equivalent for other devices than iOS).
There are probably others but you get the basic idea. Again in my opinion if your resource doesn't need authorisation then you don't need to secure that REST API. Can I ask what kind of data are you exposing via this REST API or functionality your providing? That might help provide a better answer.
You want authorization: only some agents (mobile clients) and/or users should be allowed to access those APIs.
To solve that problem, you need identification: a way for the server to tell who is who (or what), so the right decision can be made.
There are many different way to provide some form of identification, depending how much you care about security.
The simplest is a user agent string, specific to your mobile clients. But it can be faked easily. Slightly harder to fake are client based 'secrets' - embed some kind of secret or key in your mobile client code. You can make it really complicated and secret, but as ramsinb pointed out, you can't get security this way as it would require you to be able to guarantee that the secret you're shipping with the client (wether it's code, algorithm or any other fancy construct) can't be compromised or reverse engineered. Not happening when you don't control the client.
From there, 3 choices:
Security isn't really required, don't bother
Security isn't really required, but you still want to limit access to your API to either legit users/agents or people ready to invest some time hacking your protection - go with a specific user agent or a client embedded secret - don't invest much into it as it won't block people who really want access to get it anyway
Security IS required - and then I don't think there is a way around authentication, wether it's login/password, user specific (device specific?) keys, OpenID, etc... No matter what, you'll have to add to the user burden to some extent, although you can limit that burden by allowing authentication to persist (cookies, storage....)
I'm working on a REST webservice, and in particular authentication methods for browser-based requests. (using JsonP or Cross-domain XHR requests/XDomainRequest).
I've done some research in OAuth, and also Amazon's AWS. The big drawbacks of both is that I need to do either of the following:
Store secret tokens in the browser
Let a server-side script handle the signing. Basically I'd first to a request to a server of mine to get a specific pre-signed javascript request, which I'll use to connect to the real REST server.
What are some other options or suggestions?
Well, the only true answer here is proxying through a server, using sessions/cookies to authenticate and of course use SSL. Sorry for answering my own question.
Yes, jsonp call-authentication is tough, because the browser-client needs to know the shared secret.
An option would be to make the end-point anonymous (no authentication necessary). This comes with other security wholes (server is open for attacks, anyone can call it). But you could handle this by either only exposing very limited resource and/or using rate-limiting. With rate-limiting only a certain number of calls are allowed by one client in a certain range of time. It works by identifying the client (e.g. by source-ips or other client footprints).
I once experimented with one-time tokens, but they all somewhat failed because you have the problem of getting the token itself and protecting multiple retrievals of the token by bots (which comes again to the need of rate-limiting).
I havent tried this myself but you can try the following..(I am pretty sure i will get some feedback)
On the server side, generate a timestamp. Using HMAC-SHA256 an generate a key for that time stamp using a password and send the generated key and time stamp in the html.
When you make the AJAX call to the web service(assuming it is a different server) send the key and the time stamp along with the request. Check if timestamp is within a 5-15 minutes..
if it is do do the HMAC-SHA256 with the same password and key if the key generated is same.
Also on the client side you will have to check if your timestamp is still valid before making the call..
You can generate the key using the following url..
http://buchananweb.co.uk/security01.aspx