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the words in BOLD is d ERRROR... "ERROR GrabFrame()"
xxx
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the words in BOLD is d ERRROR... "ERROR GrabFrame()"
xxx
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Well that makes it so much clearer.
I must get a clever new signature for 2011.
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i dont understand...
but anyway, thanks for your effort....
just want to have a clearer answer on this things...
xxx
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The_Collector wrote: i dont understand...
Nor do I, all you have said is "the words in BOLD is d ERRROR... "ERROR GrabFrame()"", which tells us nothing. What error, what messages, what status codes, what exceptions, etc? People reading this cannot guess what happens on your system.
I must get a clever new signature for 2011.
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its a camserver.dll which doesn't give any error numbers or description, just this error....
xxx
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So how exactly do you think anyone can guess what the problem is? I suggest you go to the site or supplier of the DLL and ask them for more information.
I must get a clever new signature for 2011.
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i guess so... i'l try to reach d programmer of this dll or look for another dll..
thanks.
xxx
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In addition tp pravin answer I also suggest you to go there[^] to download a sample application to learn how to capture image using webcam.
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this is a windows application,,, Im looking for ASPX page.
thank you
xxx
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Simple .NET licensing mechanism - how to crack this (assuming exe is obfuscated?)
<br />
class Program<br />
{<br />
static void Main(string[] args)<br />
{<br />
string EncryptedLicense = System.IO.File.ReadAllText("License.txt");<br />
if (LicenseManager.Decrypt(EncryptedLicense))
{<br />
Console.WriteLine("Valid license");<br />
}<br />
else<br />
{<br />
Console.WriteLine("Invalid license");<br />
}<br />
...<br />
}<br />
}<br />
dev
modified on Thursday, March 10, 2011 10:21 PM
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Make a copy of License.txt? 
--edit--
A link to the previous[^] thread would have helped. As is now, it looks like you're trying to breach someone else's protection.
I are Troll 
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lets assume license file is encrypted + contains machine IP address or MAC code with expiration date.
But where'd you store the private decryption key?
dev
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By paying for a license. License mechanisms exist for a reason.
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He's building one, and looking how people would attack it. Ie, is this lock enough on his door to keep the bad guys out? (A typical bad guy would be the average IT-manager who notes that you can re-download the evaluation-version, or to use the key from employee A to install the same product on the PC's of employees B and C)
I are Troll
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There's a serious side to my answer. Suppose I tell him how to crack the application - then I have posted an answer in a forum that is crawled by various web crawlers; at this stage I have told just about any script kiddy out there how to do it as well. Now, this is a simplistic application, but the technique that applies will be similar.
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Pete O'Hanlon wrote: <layer>Suppose I tell him how to crack the application - then I have posted an answer in a forum that is crawled by various web crawlers;
..right
A script kid would merely download a crack, not create one - by your reasoning, we'd be helping hackers simply by reporting leaks in Windows. After all, they are holes in existing systems, and Google would index them
I'm a firm believer that any hole should be pointed out, so that it can be closed.
I are Troll
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That's right, so the only way to be secure and safe is never ever discuss security implications.
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I'm considering buying third party + on top build one myself so two layers.
dev
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Yes but how's that going to solve your problem? If their implementation is on .NET layer... then we might as well code it yourself right?
If on the other hand they patch the binary, I've reviewed one vendor's solution, you'd still end up need to write .NET level permissioning statements such as:
<br />
bool IsAuthorized = ThirdPartyLicensControl("ModuleName");<br />
if(IsAuthorized)<br />
{<br />
Module.IsEnabled = true;<br />
}<br />
dev
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For native executables, placing NOP's in the appropriate locations does the trick. I did this to mine when investigating how hard/easy it would be for them to bypass my licensing mechanism. Now granted, I knew where to look in the executable but it ended up working so I'd say, your wasting your time. I gave up with licensing schemes but still choose to obfuscate as much as is practical.
[modified]
Geez, whoever one voted my comment has obviously never applied the machine instruction 90h (as many times as needed) to an native binary exectuable to manipulate branch statement execution. You might want to look it up in the intel handbooks under "instruction sets" and maybe try manipulating the execution paths in the executable. I think you'll learn a thing or two. Also you might want to read a security book or two about why you shouldn't put any faith in hiding secrets in your code.
Granted the OP was talking about managed code but the concepts are basically the same.
modified on Friday, March 11, 2011 12:20 PM
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yes I hear you (though I dont know assembly programming)
Binary patch is the bottom line - if hacker knows where the code is which makes the comparison
<br />
IsAuthorized = LicenseController.CheckPermission("ModuleName");<br />
if(IsAuthorized)<br />
{<br />
... load the module ..<br />
}<br />
The question is, how hard/easy to spot the line? If code is obfuscated (In machine code it'd be same cmp command but there're still thousands of them hacker would need to try patching them one by one, right? This leads me to thinking dynamically generate millions of comparison operators [which is never on actual runtime execution path of course] in .NET code to further throw the sucker off the trail)
Another question is where to store decryption key?
dev
modified on Saturday, March 12, 2011 7:58 PM
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For native executables, you can attach to the process with a debugger and if the application throws up a message box saying "you don't have a license", you've basically brought them very close to the code path they are looking for. Also, there are various techniques to creating breakpoints that will make the porcess of tracing through much easier since they will be in the vicinity of the code, even if you don't give many hints.
I had a licensing scheme that obfuscated all sensitive string literals, comparison keys, etc... using a blowfish encryption scheme and I dynamically generated the encryption key using a function. All it took to bypass my code was to open the executable in binary mode (using Visual Studio) going to the byte sequence I had narrowed it down to using a simple debug trace of the process, and I replaced the appropriate bytes in the executable with the opcode for "NOP" (0x90) to eliminate the branch statement path that would have exited the application if the license was not correct and saved my settings. I was able to run the executable with it bypassing all my licensing code. All my hard work trying to protect my app was basically useless.
This was with a native app. Someone trying to manipulate your managed code will probably have an easier time backward engineering your efforts (obfuscated or not) and will easily bypass any protective licensing mechanism. Every book I have on security basically states, "don't rely on hiding secrets in your code". I would have to agree with that statement but I would still say it's not a complete waste of time trying to discourage reverse enginerring to some degree. Just don't get too convinced that you'll be able to completely prevent it as it is an exercise in futility, unfortunately.
I'd just hate to see someone else spend too much time on this endeavor since no matter how complicated you make it, it will probably boil down to a simple if/else statement in the end and those are easily manipulated.
Some may scold me for talking about "how to" here as they will say it is giving ammunition to those who want to bypass our code protections but I would argue that every security book considers this "false sense of security 101" and usually talks about this within the first 100 pages anyway. I think we are stuck with this reality, as unfortunate as it is.
Anyway, I would still encourage you to obfuscate to some degree to help protect your intellectual property.
Good luck with your project.
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Many thanks.
I think I'm included to implement *many* licensing checks at different places and dummy if-else (generate a dummy cs file/class with a simple console program) to throw them off the track (security by obscurity yes, but I'm not worried about political correctness)
Also, that "You do not have license" message box should comes from a thread, with variable delay.
dev
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Hello...
i have found some issue during, design my project.
my client request is they want improve system performance to almost max limit.
so i suggest Parallel programming solution to my client.
but how can i run my each multi thread in each core ?
i need each thread to run on each core. ( that base on c# language. )
current system model is running multi thread on multi core, but they can't control one to one structure.
For example, on quad core system model that have three business logic thread and have one monitor thread And they need running one to one.
do you have any solution in this case?
thank for your read.
SungBae.Han
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