I have a GWT app, which is deployed on the app engine. The application is basically an exam simulator. All the exam questions and answers are stored in an XML file on the server. I use JAXB parser to parse the XML file and send a list of objects to the client through GWT RPC.
I noticed that during the transit (server -> client), the entire data is visible in plain text in Firebug. Since the data (exam questions and answers) are my intellectual property (IP) and something that I give lot of value to, I'm concerned that it's very easy to steal that data. Therefore, I'm trying to find ways to do some basic encryption and obfuscate the content when it's being sent over from the server to the client.
After Googling, I came across gwt-crypto project, and within a few minutes, I was able to achieve the exact result that I wanted. The server would encrypt the data, and the client would decrypt it. In Firebug, it would show the data in encrypted format, and not as plain text.
However, I ran into an issue. After implementing encryption/decryption, I noticed that my application would not load inside my company's network, which is obviously protected by a firewall. The application works perfectly from home or even on a 3G network on my phone. Another version of the application, which does not use encryption/decryption works perfectly from within my company's network. I confirmed this by creating 2 exact same versions of the app, with the only difference between a boolean flag, that determines whether encryption/decryption is enabled or disabled.
I have the following questions here:
What is the best way to achieve the result that I want to achieve? Is gwt-crypto a good solution for that? I'm fine with any simple approach to obfuscate the data during transit. It doesn't have to be a sophisticated algorithm.
What could be the possible reason for a GWT app, with encryption/decryption enabled, not working inside a firewall? I'm really clueless on this.
I'll appreciate any help on this issue.
Using SSL is the right way to go.
In your case, given AppEngine SSL limitations, you should load your HTML normally from non-SSL domain and use cross-site RPC to load your data via SSL domain.
Update:
What is the best way to achieve the result that I want to achieve?
If you want to secure the data in transit then the only secure option is SSL/HTTP. Usually it's also the simplest one as it does not require you to change the application code, just server configuration. In your particular case (appengine with private domain), it takes more work as described above.
Is gwt-crypto a good solution for that?
No. gwt-crypto uses a key to encrpt/decrypt the data. You also need a secure way to discribute this key.
I'm fine with any simple approach to obfuscate the data during transit.
Security through obscurity in not security. It's a false sense of security, which is even more dangerous than no security. It's enough that only one of the technically capable students cracks this and soon everybody would do it.
Possible attack would go like this:
Snoop the network, get username/password of user.
Login as that user, have browser load exam data, which is now unencrypted in memory.
Dump the DOM and inspect it for exam questions.
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What could be the possible reason for a GWT app, with encryption/decryption
enabled, not working inside a firewall?
Use firebug to make sure network connections are identical, except for the encrypted content. Firewalls should not work that deep. Talk to sysadmin about it.
Related
I'm currently working on a password managing application in Meteor React and can't seem to find a way to encrypt and decrypt data on the client, with MmongoDB storing the encrypted data.
To add a little background to the task and specify what I am trying to do:
This whole application is for one single company and users are the employees only. The passwords, along with username info and some other attributes are stored in folders and users get view and edit rights to data within the folder. Passwords (along with additional info) need to be encrypted, but multiple users need to be able to access them based on the rights given to them. So when the data is encrypted, say when a person creates a password, other users with the rights to do so need to be able to decrypt this data as well. However, the decryption needs to happen on client and the server can only ever access the encrypted data.
I have tried using planifica:encryption, because it has exactly what we need for our project, but I ran into some errors and I can't get past them nor find any article about them. I have heard of Mylar in some answers to similar questions, but both Mylar and Planifica don't seem to have been updated for a few years now. I know Node.js has a crypto module, but I am not sure whether it could be used to share encrypted data among users and most importantly, how to do so.
Is there any way to do what we need for this project? I should also point out that I am relatively new to meteor and I have not dealt with encryption whatsoever, so my understanding is rather limited.
Thank you for reading!
This very much depends on the encryption you are using, but since you are interested in decrypting things client-side, it sounds like what you are looking for is the SubtleCrypto web api.
That should be all you need on top of what Meteor already provides. You should be able to use a regular meteor collection and publication to share the encrypted data with your clients, and then let them decrypt it using the above linked decrypt function. One question I'd have is how you will be able to get the decryption key to your clients while hiding it from the server, but I assume you've got that part figured out somehow.
I'm developing an iOS app that used GAE as a backend. The only sensitive data my app will transfer to GAE is login details, anything else that is transferred is not sensitive. I intend to use SSL for everything, just coz that seems most sensible to me - is there any reason not to? Also, I want some way of ensuring that my app is the only way that my GAE system can be accessed (ie nobody accessing it from the web/spoofing a client to look like mine) how do I go about this? I read something about public and private keys but wasn't exactly sure if it was relevant?
Any help is much appreciated
Thanks!
Short answer for your last question: you cant. There is no way you can enforce that your application is only accessed through your IOS app.
You can make it as hard as possible, but you cant guarantee that. The correct way is not relying on your IOS application
to validate the data send, but to do this verification in your gae app (if needed: again).
SSL is a good thing anyway - if done correctly (see: http://www2.dcsec.uni-hannover.de/files/android/p50-fahl.pdf )
But if the only sensitive data send is a password, you could consider using something like SRP ( start reading here: http://en.wikipedia.org/wiki/Secure_Remote_Password_protocol )
Anybody here has actually implemented any logging strategy when application is running as XBAP ? Any suggestion (as code) as to how to implement a simple strategy base on your experience.
My app in desktop mode actually logs to a log file (rolling log) using integrated asop log4net implementation but in xbap I can't log cause it stores the file in cache (app2.0 or something folder) so I check if browser hosted and dont log since i dont even know if it ever logs...(why same codebase)....if there was a way to push this log to a service like a web service or post error to some endpoint...
My xbap is full trust intranet mode.
I would log to isolated storage and provide a way for users to submit the log back to the server using either a simple PUT/POST with HttpWebRequest or, if you're feeling frisky, via a WCF service.
Keep in mind an XBAP only gets 512k of isolated storage so you may actually want to push those event logs back to the server automatically. Also remember that the XBAP can only speak back to it's origin server, so the service that accepts the log files must run under the same domain.
Here's some quick sample code that shows how to setup a TextWriterTraceListener on top of an IsolatedStorageFileStream at which point you can can just use the standard Trace.Write[XXX] methods to do your logging.
IsolatedStorageFileStream traceFileStream = new IsolatedStorageFileStream("Trace.log", FileMode.OpenOrCreate, FileAccess.Write);
TraceListener traceListener = new TextWriterTraceListener(traceFileStream);
Trace.Listeners.Add(traceListener);
UPDATE
Here is a revised answer due to the revision you've made to your question with more details.
Since you mention you're using log4net in your desktop app we can build upon that dependency you are already comfortable working with as it is entirely possible to continue to use log4net in the XBAP version as well. Log4net does not come with an implementation that will solve this problem out of the box, but it is possible to write an implementation of a log4net IAppender which communicates with WCF.
I took a look at the implementation the other answerer linked to by Joachim Kerschbaumer (all credit due) and it looks like a solid implementation. My first concern was that, in a sample, someone might be logging back to the service on every event and perhaps synchronously, but the implementation actually has support for queuing up a certain number of events and sending them back to the server in batch form. Also, when it does send to the service, it does so using an async invocation of an Action delegate which means it will execute on a thread pool thread and not block the UI. Therefore I would say that implementation is quite solid.
Here's the steps I would take from here:
Download Joachim's WCF appender implementation
Add his project's to your solution.
Reference the WCFAppender project from your XBAP
Configure log4net to use the WCF appender. Now, there are several settings for this logger so I suggest checking out his sample app's config. The most important ones however are QueueSize and FlushLevel. You should set QueueSize high enough so that, based on how much you actually are logging, you won't be chattering with the WCF service too much. If you're just configuring warnings/errors then you can probably set this to something low. If you're configuring with informational then you want to set this a little higher. As far as FlushLevel you should probably just set this to ERROR as this will just guarantee that no matter how big the queue is at the time an error occurs everything will be flushed at the moment an error is logged.
The sample appears to use LINQ2SQL to log to a custom DB inside of the WCF service. You will need to replace this implementation to log to whatever data source best suits your needs.
Now, Joachim's sample is written in a way that's intended to be very easy for someone to download, run and understand very quickly. I would definitely change a couple things about it if I were putting it into a production solution:
Separate the WCF contracts into a separate library which you can share between the client and the server. This would allow you to stop using a Visual Studio service reference in the WCFAppender library and just reference the same contract library for the data types. Likewise, since the contracts would no longer be in the service itself, you would reference the contract library from the service.
I don't know that wsHttpBinding is really necessary here. It comes with a couple more knobs and switches than one probably needs for something as simple as this. I would probably go with the simpler basicHttpBinding and if you wanted to make sure the log data was encrypted over the wire I would just make sure to use HTTPS.
My approach has been to log to a remote service, keyed by a unique user ID or GUID. The overhead isn't very high with the usual async calls.
You can cache messages locally, too, either in RAM or in isolated storage -- perhaps as a backup in case the network isn't accessible.
Be sure to watch for duplicate events within a certain time window. You don't want to log 1,000 copies of the same Exception over a period of a few seconds.
Also, I like to log more than just errors. You can also log performance data, such as how long certain functions take to execute (particularly out-of-process calls), or more detailed data in response to the user explicitly entering into a "debug and report" mode. Checking for calls that take longer than a certain threshold is also useful to help catch regressions and preempt user complaints.
If you are running your XBAP under partial trust, you are only allowed to write to the IsolatedStorage on the client machine. And it's just 512 KB, which you would probably want to use in a more valuable way (than for logging), like for storing user's preferences.
You are not allowed to do any Remoting stuff as well under partial trust, so you can't use log4net RemotingAppender.
Finally, under partial trust XBAP you have WebPermission to talk to the server of your app origin only. I would recommend using a WCF service, like described in this article. We use similar configuration in my current project and it works fine.
Then, basically, on the WCF server side you can do logging to any place appropriate: file, database, etc. You may also want to keep your log4net logging code and try to use one of the wcf log appenders available on the internets (this or this).
For Windows.Forms, I have an application that needs to get a unique install id for each install from my server, and then persist this data so once registered, the install ID is included on all communications back to the server. The application is in occasional contact with the server.
How can I persist this data on the client in a way that is not easily tampered with?
First, you should note that if the data is on the local file system and your application can read and write it, it will always be possible for a determined user to tamper with it... perhaps not easy, but possible nonetheless.
That said, there are a number of options you could consider, including (but not limited to) :
encrypting the data with a key defined in your assembly : pretty safe is the user has no programming skills, but an advanced user could disassemble your app to find the key. Obfuscation could make it harder to extract the key, but not impossible.
using an isolated storage : I'm not sure whether the data is encrypted or not, but at least it's not easily found, hidden in a deep folder hierarchy... Not so safe is the user knows where to look, however
writing the data in a binary format, which makes it harder to read or modify for a non expert user
using a piece of native code to encrypt the data : similar to the first option, but a native DLL is harder to disassemble than a .NET assembly, so it requires more skills to find the key
Again, all these approches are not bulletproof : as long as your program can access the data, an advanced user could always reverse engineer it and do the same...
You could save the data in the windows registry. You'll use the [HKCU\Software\YourAppName] hive key if it's a per-user setting, or [HKLM\Software\YourCompany] if it's a global setting. However, the data would need to be encrypted, because its trivila to get the values in these keys
I am wondering any efficient way to hide our Silverlight code. I know there are some obfuscators available but it looks like people can hack that too. Anybody have any success on this front?
Pragma No-Cache on the page hosting the silverlight application will prevent the the browser from caching the xap, instead it will read it by streaming from the web server. That will make it harder for peeps to get the xap. Obfuscation will make it harder still.
Also make sure the app is hosted in https, have authentication take place outside the main application. This way the xap stream is encoded on the way down.
You really can't hide anything that gets transmitted to the client. If people want to figure it out, they will.
You need to put any proprietary code in your back-end where client machines can't get at it.
No. The client browser must be able to read the code, therefore it is hackable.
Here is a short article on how to obfuscate a xap file
http://www.rudigrobler.net/Blog/obfuscating-silverlight
You could complicate the potential hacker's job by downloading obfuscated fragments of your app during execution, using MEF for instance. Needless to say that it's interesting if your application is big enough so that this astuce speed up startup time rather than hindering the user's experience.
It won't prevent a valorous hacker from getting your code (in the hand no method can prevent this, as the Silverlight plugin must be able to execute it), but the astuce will complicate his task greatly.
preventing the browser from caching the XAP is useless, like using HTTPS, as it's far easier for the attacker to use something as complicated as firebug to get the XAP than looking for it in the browser cache or using a Man in the Middle Attack.
I imagine that if you had lot of motivation, you could:
obfuscate every assemblies
use dynamic loaded XAPs
encrypt the dynamic loaded XAP serverside and decrypt it client side using a dynamicly generated key sent by a webservice (Not in the same request. And don't reuse the key.)
It won't prevent the attacker from getting your code, but he will have to analyse your initial (obfuscated) xap to understand the decryption code, get the key, get the encrypted (obfuscated too) dynamic loaded XAP, decrypt it, then manage to unobfuscate it, then understand how it plugs itself in the application.
It's not the same as using HTTPS, because here the encryption and decryption process is done in the application so that tools like firebug or fiddler become useless.
Hem. Nothing can prevent anyone from reading your code. BUT you can make it not worth his time. You don't have to use all the ideas here and I am sure that you can find others, but make sure that implementing such measures are worth your time too.
Either way, it was rather funny to write this :p
You cannot hide (at least not non-trivially) XAP files. But you can obfuscate them. Obfuscation is not a definitive answer, but its a start and can give pretty good protection.