I've setup a Windows Azure database with the data accessible via oData. I'm trying to work out how to secure the connection between a WP7 device and the database. By secure I mean I only want users of the app to be able to access the data from within the app.
I've considered SSL but it's quite expensive for me - is there another way of securing this connection?
Thanks!
There are multiple definitions of "secure". You will need authentication, so Azure only lets the correct users access the data. This is usually handled by a user name and password supplied by the WP7 app.
The WP7 app needs to ensure it is talking to the correct server. SSL handles this using a digital certificate. There are other mechanisms but using something based on a public/private key pair is best because you can validate you are connecting to the correct server without being able to impersonate that server. However, the RSA algorithm used in most cases is computationally expensive.
The data sent between the WP7 app and Azure also needs to be confidential, including the user's password. This is normally handled by encryption. You an choose computationally less expensive algorithm or only encrypt certain data.
The data sent between the WP7 app and Azure also needs some form of tamper detection. Otherwise someone could corrupt the data sent or received. Maybe this is something you can accept for the app but it needs to be a way that an attack cannot easily reproduce. As Shanin's Maxim says, the attacker knows the system.
The problem is that SSL gives you all of these. Yes, it can be expensive but it is one of the best general purpose solutions available. You can change the cipher suites offered by Azure using using Group Policy, code or PowerShell.
If you do not want to use SSL, you need to know what you can sacrifice. In general I would not recommend doing your own encryption mechanism or protocol because us mere humans tend to screw it up.
Related
Currently I'm developing a Node.js webserver-app that I then want to make available for download and use. This app should feature accounts, so that you can log in with your account on the website created by the server.
Since that would require a password, I also have to think about security obviously. But now, I don't really know how I should protect the password while sending and receiving it.
For storage, I was about to simply create a hash of the password and store that hash somewhere, but what about the transfer?
I was thinking about SSL/https, but this would require a SSL certificate, and even if I got it for free somewhere, I couldn't share it in an open-source app(?).
I could also somehow hash the password in the website, and then just send the hash to the server, but I think this wouldn't be the highest standard of security as well, would it? Considering that no SSL would cause more disadvantages than just worse/none encryption.
Any ideas?
I was thinking about SSL/https, but this would require a SSL certificate, and even if I got it for free somewhere, I couldn't share it in an open-source app(?).
Use SSL/TLS. Even if it's an open source app, it doesn't mean that you need to share your private key too. This would undermine the whole concept.
Open source means that you share the code with some license. What the licensor does with it is not your consern as long as they conform to the license. If they want to use their own instance of your software under their own domain, they will have to create their own certificate (under their domain).
I could also somehow hash the password in the website, and then just send the hash to the server, but I think this wouldn't be the highest standard of security as well, would it? Considering that no SSL would cause more disadvantages than just worse/none encryption.
This is no solution, because you now changed the thing you want to protect to something else. The model doesn't change just because you hash it on the client. Now you need to protect the hash on the transport channel which is actually the same problem as you would have had before with sending a password.
Currently I'm developing a Node.js webserver-app that I then want to make available for download and use. This app should feature accounts, so that you can log in with your account on the website created by the server.
Federated accounts
If you want federated accounts across multiple instances of your app which are hosted by different parties.
You could look into OpenID as an identity provider for all instances of your app. You would then either require that users use a known OpenID provider or you setup your own default provider. You could release the code for your provider as open source, but it wouldn't be necessary for the app to function.
If the OpenID interface is not enough, there is always a way to establish a pairing between instances of your app. You would have to build an interface where different instances may share data.
Unconnected instances
If this is only about securing the communication without SSL/TLS, then I must say, this is impossible in the general sense.
You could however let every student register in person and use that password on client and server to derive a shared secret key (i.e. for AES). Then you could use CryptoJS to encrypt everything with AES and send it using AJAX. The problems are of course that (1) there must be a person that handles the registration and (2) this is vulnerable to man-in-the-middle attacks, because JavaScript crypto is bad.
Good thing is that Let’s Encrypt will be online soon. It will enable a semi-automated way to request free certificates for your domain. It will be so easy that you can do this as part of the normal NPM install workflow.
http://letsencrypt.org works great for this and is now available (I understand I am a little late to this one.)
You can check out https://github.com/DylanPiercey/auto-sni for automated Letsencrypt certificates.
I am looking into ways of securing the channel between my client apps and the server.
I have a rich desktop client (win) and mobile client connecting to a webservice, exchanging data.
Using SSL certificates, server and clients may trust each other. On the secured connection i can exchange username and password and therefore authenticate the user.
However i have certain circumstances where a user must connect to the server via any of the two methods without his credentials but only a literal, like say, a license plate number.
I really want to make sure that in this case i ONLY allow client connects from devices i am sure i know, since there is no further checks on the authentication and a license plate number would be a pretty common literal.
How can i ensure that only "devices" which are known to my server, can interact with my server?
If you want to authenticate the device, you'll need to find a way for the device to prove what it is, without disclosing its secret.
A system similar to a number plate would be quite easy to spoof, for anyone in a position to see that number. Depending on how much control you have on this device, you might not be able to hide it, even if the connection to your server is secured with SSL/TLS.
A potential way to do this would be to use a cryptographic hardware token (or smart card). Some of these tokens can be configured to hold a certificate and private key, with the ability to use the private key without being able to export that private key. The cryptographic operations (signing and decryption) happen on the token itself.
You can use these to perform client-certificate authentication to your server. In this case, you would know that the client has that token. This could work on the condition that you know the CAs were issued its certificates only for key pairs in such tokens: there will be a cost in administering the CA to handle this.
This would at least allow you to tie the authentication to a particular token. Whether you can integrate this with your overall device depends on the kind of device you have.
Please check if TLS Pre-Shared Keys (RFC 4279) can be used for your scenario.
Suppose you have a server-client application.
Server keeps sensitive information that belongs to a Client.
Server will search some parameters in side the clients's sensitive information.
Thus server should decode the sensitive information with client control temporarily.
But server should not reveal the keys, by hacking it self.
I mean a developer should not try to change server sidde code and should not extract the client keys.
Is there really a way to do that?
Somewhat client permits server to decode sensitive information, but the keys instantly disappear and developer have no tricks to reveal this password?
The answer if exist, is valid also for an ideal secure cloud application. Developer or cloud hosting company should not access to decrypted information.
I am not optimistic, but worth to try asking.
So in a word no. This does not grant any security whatsoever, as you cannot trust the client. You even call out that the server will be controlled by the client temporarily, this is generally not a wise approach. Also, do not underestimate a bored developer, it is completely feasible to write some code and rip the keys. The key here is remembering that if someone has access to the box it is no longer your box.
In general, any client access to sensitive info on the server must require authentication of the client, so that you can verify that the client is exactly who he claims he his. The authentication typically involves sending a password, or some kind of authentication token (e.g., an encrypted shared secret) that was given to the client by the server through a secure channel.
As has been said many times, many ways, allowing client access to server data without proper and sufficient authentication means that you give up control of the server.
As part of strengthening session authentication security for a site that I am building, I am trying to compile a list of the best ways to register a user's computer as a second tier of validation - that is in addition to the standard username/password login, of course. Typical ways of registering a user's computer are by setting a cookie and or IP address validation. As prevalent as mobile computing is, IP mapping is less and less a reliable identifier. Security settings and internet security & system optimization software can make it difficult to keep a cookie in place for very long.
Are there any other methods that can be used for establishing a more reliable computer registration that doesn't require the user to add exceptions to the various cookie deleting software?
If you're looking to do device authentication, you may want to consider mutually authenticated SSL. Here, you'd deploy a client identity certificate to each endpoint you'd want to authenticate. Then, you set the server up to require client authentication, so that a client would need to present a valid identity certificate in order to form the SSL tunnel.
This, of course, is not a perfect solution. In reality, this presents much of the same weaknesses as other solutions (to various degrees) Once your client identity certificates go to your clients, they are out of your control; should a client give their certificate to anyone else, you lost the device authentication that you have based on it. SSL identity certificates are generally stored in a keystore on the client which is encrypted with a password or other credential needed to unlock them. While a client certificate could still be compromised, it's somewhat stronger that just a cookie or something like that (assuming you don't have a client that is trying to give away its credential). In addition, you'd want to come up with some validation routine that a client would need to go though in order to get a credential in the first place (how do I know that this is a client device that I want to remember/register?).
Remember, these types of approaches only do device authentication, not users. There are more in-depth schemes already developed for device authentication than what I've mentioned; for example, 802.1x is a network protocol where an endpoint needs to present a client-side certificate to the network switch to get on a LAN. This is out-of-scope for a web application scenario, like what you've described, but the idea is the same (put a cryptographic credential on the client and validate it to establish the connection).
This, like all other security matters really, is a risk decision. What are you trying to accomplish with such a countermeasure? What are the threats you're trying to prevent and what are the consequences if someone does log in on an unregistered device? Only your situation can answer those questions and let you see the real risk, if you need/should mitigate it, and, if so, how strong of a solution do you need to get the risk level down to an acceptable level?
the best ways to register a user's computer as a second tier of
validation
From my point of view this approach does not offer much in the aspect of authentication.
You are not authenticating a user and have no idea who is using the PC that you would accept as being registered.
The way you describe it, this step should be a configuration rule in the firewall to accept connections from specific IPs only.
IMO the filtering of the PCs is the responsibility of a firewall and it would be much better handled by the firewall than any application level filtering.
Just think that you would have the overhead in your application to examine each request and decide whether to accept it or not.
Better leave this preprocessing overhead to the firewall. That's why it is there.
We're developing a REST API to be consumed by a couple of mobile applications. It's important that we're able to trust the identities of these mobile applications. In our current design, each API call is authenticated with an "API Key" parameter and secured with HTTPS.
My concern is that the API Key is embedded within each copy of the mobile app, which means there's no way we can keep it secret. It will be on thousands of phones, and theoretically any hacker with a binary editor or HTTP Traffic analyzer could extract the API key and then 'pose as' one of the applications, sending us requests that we'd have no choice but to trust. Client certificates would appear to have the same risk.
Is there an architecture that solves this problem?
It is being discussed from time to time in different places including StackOverflow. In brief - whatever you put to user's possession is not yours anymore. You can obfuscate the private key, of course, yet I see at least three ways to bypass your security measures.
The only way to solve a problem could be to employ cryptographic device (smartcard or USB cryptotoken) which keeps private and secret keys and doesn't let them out, however with handhelds use of such devices is quite complicated (if not impossible) from both technical and usability points of view.
Also you might want to reconsider your approach and let any client software use the service given that they pay for it. And your server will authenticate users and not software. Then the topic of keeping login data secret will be users' task.