Is it possible to use salted password along with standard HTTP authentication schemes ( FORM or DIGEST ) ?
I am using GlassFish, and when I request a protected page, the form or the answer with the nonce are sent back directly by the server. I can't see any obvious way to hook into the server mechanism to insert the salt in the 302 response ( which I thought could be a good idea ). Thus the password I return can just be hashed without salt.
Is it so ?
Thank you.
Related
I need to authenticate users using an api key, but before handling it over to them I need to check their credentials, obviously. I think the process needs to go like this:
client->server: GET /user?username=fred
server->client: nonce=XYXY
client->server: POST /login?hashval={hash(username + password + nonce)}&nonce=XYXY&username=fred
server compares the result of hash(username + passwordFromDB + nonce) with hashval and responds with the API-key if equal
But if there was somebody eavesdropping the connection, although it wouldn't be able to directly discover my user's password, since it already knows the username and the nonce, if the password was easy enough the man-in-the-middle would be able to match my hash by trying all the generic possible values for the password.(brute-force attack)
I know connection over HTTPS and a strong password would make this process secure, but are there any other recommendations or ways of making this process more secure?
Thank you
This is basically a form of digest access authentication and as such has its same limitations.
Since all the details to compute the hash are sent along with the hash, the only thing that an attacker needs to "reverse" is the password. If that is weak, then rainbow table or brute force attacks could crack it. The only way to delay an attacker is to have a very long and strong password.
But since you are using an API key for service authentication, as a man-in-the-middle attacker I would let you authenticate with a password and then just get the API key from the response. I assume you use the API key for authentication of the rest of the requests (just like a session cookie is doing for web applications)?
There are of course other variations of securing a service, depending on what you are doing, but actually making it secure means using HTTPS as you mentioned yourself.
I am currently working on a API site based on Zend Framework. As ZF doesn't have sufficient support for Digest Authentication and it is too late to shift to another framework now, I am thinking of implementing Basic Authentication.
Basic and Digest are not actually the ideal way to perform authentication, while Digest is better but unfortunately not quite supported by Zend (implementing it properly will take too much work, need the project done asap). One of the big problem with Basic auth is that password is sent in cleartext form. I am thinking instead of sending the password in cleartext form, can I somehow hash it using one-way-hashing algorithm / bcrypt to avoid sending password in cleartext form? But it is still suffering from man-in-the-middle attack though.
But if comparing the basic authentication with current form-based authentication used by most web-apps, are they both sharing the same security problem while transferring the request to the server?
Your best option for keeping the request secure is to use SSL for your authentication requests to ensure that the information isn't sent in plaintext.
If you try to do some kind of hashing or encryption on the client before sending the authentication request, you immediately expose your hashing algorithm and any salts you might be using to malicious users. This makes it possible for them to use dictionary attacks against your server.
But if comparing the basic
authentication with current form-based
authentication used by most web-apps,
are they both sharing the same
security problem while transferring
the request to the server?
Absolutely they are. Again with forms based authentication your best bet is to use SSL.
Alternatively, you might consider using an external authentication service like OAuth.
Hum, Zend Framework has an Digest Adapter for Authentication?
Manual: Zend Digest Authentication
You could always write your own Zend_Auth_Adapter for HTTP authentication. I implemented Zend_Auth_Adapter_Http_Resolver_Interface to have different passwords each day in the format of default password + day + month. Works like a charm!
Consider the following interaction:
A user stores their username and password on a web server. For the sake of security, the server records a hash of the password plus some unique salt.
While the user is using a client application, it makes a request to the server submitting their username and a hash of the password plus some other unique salt.
So you have the following information on the server and need to know whether or not the request is authentic:
The server's salt
The server's hashed password
The client's salt
The client's hashed password
Again ... client sends: clientSalt + MD5(clientSalt + password). Server has serverSalt + MD5(serverSalt + password). I don't want to know the password, I just want to know if the hashes were calculated from the same password.
Without knowing the password that was hashed, is there any way to verify that both hashes are of the same password?
My goal is to allow some form of secure authentication in a client-server environment without ever exchanging the actual password over the wire. This is just one idea I've had, but I don't even know if it's possible.
That would require unhashing the password, which is not possible. If the server receives: salt, md5sum, it can't see what went into the md5sum.
A challenge-response protocol would work instead. The server should generate a random value nonce and send it to the client. The client calculates md5(md5(password) | nonce)) and returns it to the server. The server verifies by checking md5(storedpassword | nonce).
No, you can't do this.
Once you add a salt into the mix it becomes practically impossible to compare hashes. (To do so would require "un-hashing" those hashes somehow before comparing the "un-hashed" data.)
Challenge-response authentication is probably the way to go, possibly using Kerberos, depending on your tradeoffs. One of the tradeoffs being the possibility for attackers controlling the clients to use compromised hashes to authenticate themselves.
Don't invent your own cryptographic protocols. Use one that is well-known and well tested. If possible, use an existing (vetted) implementation.
My goal is to allow some form of secure authentication in a client-server environment without ever exchanging the actual password over the wire. This is just one idea I've had, but I don't even know if it's possible.
For this, I advise looking into Kerberos: Official Site and Wikipedia
It's impossible. If you don't store password on the server, user must provide it.
OR
If you store password on the server, user can provide hash calculated using requested salt.
You will not be able to verify the hash with this setup.
If you don't want someone to see the password go over the wire, SSL is the easier way.
If you don't want to use SSL, you could check out SRP.
Additionnally: don't use MD5+Salt to store your password, use key strengthening functions like bcrypt or scrypt.
I am developing a web service and I need to send a username and password to the service in a GET method. Is it OK to send this information in the uri as long as it's going over a secure channel like ssl? In other words, can I have a uri that looks like /users/{username}/{cleartext_password}?
Edit: Sorry, I think I was unclear. The web service is essentially just a database of usernames and hashed passwords. Imagine a desktop application that keeps usernames and passwords in a remote database. The end user types their username and password into the application and the application accesses the web service to authenticate the user.
So, the application will need to send an end user's username and plaintext password to the service. The service will take the username and password and check that the username and the hash of the password match the username and hashed password in the database. The application itself will have to authenticate before it can access the service, but I am just wondering what is the best way to send the end user's username and password to the service for authenticating the end user. I don't to use a POST method because I am simply authenticating and therefore not changing the state of the server. Sorry for the confusion.
Do this.
Send a "key" and a "digest".
The "key" is equivalent to a username.
The "digest" is a SHA1 (or MD5) hash of the key, the URI and a "shared secret" or password.
When the server gets this, it computes it's own version of the digest, based on key, URI being requested and the "shared secret" or password. Failure to match digests is a 401 error response.
If it's going over a secure channel, there's no problem sending the username and password as cleartext. I'd just recommend against ever sending them as cleartext through an insecure channel and against sending them repeatedly for each request.
What you could do is first authenticate to the web service (send the username and password via ssl as cleartext) and get a token from the server that it will recognize. Then send that token with each subsequent request.
Generally speaking this is not a good idea... This data will be present in a number of log files, consequently the data could be visible to people who should not see it. At the very least you should hash or encrypt it before sending it if you can.
Here is a related discussion for a little more detail... Is an HTTPS query string secure?
SSL does encrypt the URI, but definitely take a look at some alternatives.
HTTP Basic Auth is nice and simple, and well supported by browsers, webservers, etc
It also won't end up in log files to the same degree as URIs
NB: It's just some plain-text HTTP Headers, so definitiely NOT recommended for non-SSL apps.
http://en.wikipedia.org/wiki/Basic_access_authentication
Background:
I'm designing the authentication scheme for a REST web service. This doesn't "really" need to be secure (it's more of a personal project) but I want to make it as secure as possible as an exercise/learning experience. I don't want to use SSL since I don't want the hassle and, mostly, the expense of setting it up.
These SO questions were especially useful to get me started:
RESTful Authentication
Best Practices for securing a REST API / web service
Examples of the best SOAP/REST/RPC web APIs? And why do you like them? And what’s wrong with them?
I'm thinking of using a simplified version of Amazon S3's authentication (I like OAuth but it seems too complicated for my needs). I'm adding a randomly generated nonce, supplied by the server, to the request, to prevent replay attacks.
To get to the question:
Both S3 and OAuth rely on signing the request URL along with a few selected headers. Neither of them sign the request body for POST or PUT requests. Isn't this vulnerable to a man-in-the-middle attack, which keeps the url and headers and replaces the request body with any data the attacker wants?
It seems like I can guard against this by including a hash of the request body in the string that gets signed. Is this secure?
A previous answer only mentioned SSL in the context of data transfer and didn't actually cover authentication.
You're really asking about securely authenticating REST API clients. Unless you're using TLS client authentication, SSL alone is NOT a viable authentication mechanism for a REST API. SSL without client authc only authenticates the server, which is irrelevant for most REST APIs because you really want to authenticate the client.
If you don't use TLS client authentication, you'll need to use something like a digest-based authentication scheme (like Amazon Web Service's custom scheme) or OAuth 1.0a or even HTTP Basic authentication (but over SSL only).
These schemes authenticate that the request was sent by someone expected. TLS (SSL) (without client authentication) ensures that the data sent over the wire remains untampered. They are separate - but complementary - concerns.
For those interested, I've expanded on an SO question about HTTP Authentication Schemes and how they work.
REST means working with the standards of the web, and the standard for "secure" transfer on the web is SSL. Anything else is going to be kind of funky and require extra deployment effort for clients, which will have to have encryption libraries available.
Once you commit to SSL, there's really nothing fancy required for authentication in principle. You can again go with web standards and use HTTP Basic auth (username and secret token sent along with each request) as it's much simpler than an elaborate signing protocol, and still effective in the context of a secure connection. You just need to be sure the password never goes over plain text; so if the password is ever received over a plain text connection, you might even disable the password and mail the developer. You should also ensure the credentials aren't logged anywhere upon receipt, just as you wouldn't log a regular password.
HTTP Digest is a safer approach as it prevents the secret token being passed along; instead, it's a hash the server can verify on the other end. Though it may be overkill for less sensitive applications if you've taken the precautions mentioned above. After all, the user's password is already transmitted in plain-text when they log in (unless you're doing some fancy JavaScript encryption in the browser), and likewise their cookies on each request.
Note that with APIs, it's better for the client to be passing tokens - randomly generated strings - instead of the password the developer logs into the website with. So the developer should be able to log into your site and generate new tokens that can be used for API verification.
The main reason to use a token is that it can be replaced if it's compromised, whereas if the password is compromised, the owner could log into the developer's account and do anything they want with it. A further advantage of tokens is you can issue multiple tokens to the same developers. Perhaps because they have multiple apps or because they want tokens with different access levels.
(Updated to cover implications of making the connection SSL-only.)
Or you could use the known solution to this problem and use SSL. Self-signed certs are free and its a personal project right?
If you require the hash of the body as one of the parameters in the URL and that URL is signed via a private key, then a man-in-the-middle attack would only be able to replace the body with content that would generate the same hash. Easy to do with MD5 hash values now at least and when SHA-1 is broken, well, you get the picture.
To secure the body from tampering, you would need to require a signature of the body, which a man-in-the-middle attack would be less likely to be able to break since they wouldn't know the private key that generates the signature.
In fact, the original S3 auth does allow for the content to be signed, albeit with a weak MD5 signature. You can simply enforce their optional practice of including a Content-MD5 header in the HMAC (string to be signed).
http://s3.amazonaws.com/doc/s3-developer-guide/RESTAuthentication.html
Their new v4 authentication scheme is more secure.
http://docs.aws.amazon.com/general/latest/gr/signature-version-4.html
Remember that your suggestions makes it difficult for clients to communicate with the server. They need to understand your innovative solution and encrypt the data accordingly, this model is not so good for public API (unless you are amazon\yahoo\google..).
Anyways, if you must encrypt the body content I would suggest you to check out existing standards and solutions like:
XML encryption (W3C standard)
XML Security