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It could be how you're storing data. A common error is to take the blob (a byte[]) and write it to a text file. This won't work correctly, since text files store data differently and the bytes will be encoded incorrectly.
Either use an encoding (the common encoding is base64, for which you can use the ToBase64Transform and FromBase64Transform classes) and write the blob to a binary file (using a FileStream, as opposed to a StreamWriter or a StreamReader for example).
The exception you got is consistent with this type of problem. The cipher block or cipher text is not stored correctly and, therefore, will not decrypt when you read it in.
If this doesn't seem to be the case, please provide more information that may be helpful.
Microsoft MVP, Visual C#
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thanks for your help!
my encryption steps:
(1) create a symmetricalgothrim instance
(2)a.use automatically generated key and IV to encrypt data and then stored
the key and IV and cipher data(use binarywriter) to a file;
OR
b.use a password and salt value (byte[])to generate key (use PasswordDeriveBytes),and then stored the IV and salt and cipher data in file.
(3) encoding all data with base64
my decryption steps:
(1) decodeing all data with base64
(2) a.read the key and IV to decrypt
OR
b.use the same password&salt to generate the key(the key and IV are same with the previous) to decrypt
but the exception throwed when "b" is executed and everything is ok when a is executed
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First of all, you should not store the key and cipherdata together. Where's the security in that? If nothing else, store them in a separate file (binary file if you keep the blob (byte[] array), or base64-encode it for a text file).
Second, off-hand I don't see anything wrong with your approach. Have you actually done a binary comparison of the generated key from the password and salt to see if they're the same?
Microsoft MVP, Visual C#
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once i use the password derived key ,the exception will be throwed,the code listed below:
RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); rng.GetBytes(salt); PasswordDeriveBytes pdb = new PasswordDeriveBytes(password,salt);
byte[] key = pdb.GetBytes(crypter.KeySize/8); crypter.Key = key;
i found that if commented the last sentence,
the program will be ok,but if i use the password derived bytes ,the exception will be throwed ,it is so strange that i don't understand at all~~
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Hi,
Is it possible to make the windows application distributed using IIS. Please sewnd me some info. about the same.
Ravindra
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Depends what you mean. You can always place the exe in an IIS folder and link to it via a normal hyperlink in a webpage or navigate directly to it. There is also the codeBase element of the app config file that can tell were to find assemblies for your app.
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Yes you could by placing the .exe into your web directory however its not the most elegant/safest solution out there. I would recommend using the Updater Application Block pattern for this. This way all of your applications will update from a single central server and all the new updates will be guaranteed to be the ones you have provided because of a cryptographic hash. You can download the code and read about this pattern more here: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/updater.asp
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If you strongly name your assemblies, you would already have a cryptographic hash. There is no excuse not to strongly name your assemblies, and it's incredibly simple to do (even more simple that using the UAB). Fusion - the binding manager for the CLR - will even download updated assemblies automatically and cache them in the temporary assembly cache (or TAC, as I call it, though that doesn't seem to be an "official" acronym).
I developed a large N-tier solution using this approach back in 1.0 beta 2 and it works well without the UAB. The UAB does, however, provide you with the capabilities of a disconnected application that updates itself when connected (if any updates are available).
ClickOnce is like a combination of both techniques and we are looking at it for future deployment when released with .NET 2.0 for the only big advantage that the UAB has as I mentioned above: removing the requirement to be always connected (but for a smart application it's pretty much required without a data cache anyway).
Microsoft MVP, Visual C#
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I have a datatable where I want the top row containing "Time" data to stay at the top when I sort the table by pressing the column headers. The way it is now the "Time" row gets sorted alphabeticly like the other rows.
I have thought of a solution which involves searching for the "Time" row after sorting. When found, remove from place found and insert it at the top. Is there an easier way?
-Atle
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Could you put the "Time" data in the actual column headers instead of the first row of your grid?
If that's not acceptable, you could remove row 0 from your dataset, sort the thing, then insert your time back into the dataset at position 0. It's probably a little faster than searching...
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To put it in the column headers was a good idea. But then I got a new problem. If I import data from a new file (and fill the datatable and set the new table as the grids datasource) and the timedata has changed or now is data for "Depth" or not present at all (the column names has changed), the table is not drawn. I get the row headers, but no columns. I have tried to reset the datatable and set datasources to NULL and a lot of other things to reset the table/grid, but I can't make it work. I can only imort files that have the same timedata as the first file i imported. Or else nothing is drawn. This datagrid/datatable thing is really wierd. It even gets slower and slower to select rows for each file I import.
-Atle
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I have followed the article and project "Customising the header control in a ListView" by Georgi Atanasov, so that I can increase the hight of the header, brilliant. However, if I turn on the XP visual styles with:
Application.EnableVisualStyles();
I no longer get the increase in hight of the header control. Does anyone know how I can use the custom header control of the ListView and also keep the XP visual styles?
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The only way is to define your own window class that functions like a header control and draw the theme parts yourself. This is not a simple task, especially using C# (since there's a lot of native functions and structs you must P/Invoke and define). There are some articles on CodeProject about drawing theme parts, however. I would suggest using the search bar below the logo above to find them, or browse the categories.
Microsoft MVP, Visual C#
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I've written an app in C# - let's call it Foo. Foo creates *.Bar files. I want to enable double click support in Windows for *.Bar files, so Windows automatically opens the file in a running instance of Foo.
I already know how to get Windows to start Foo up when I double click on a .Bar file - simply associate the file type using Windows Explorer (for example), and use the args[] string array argument in the Main(args[]) method of Foo. This acts as a list of files to open when Foo starts up. But what happens when Foo is _already_ running? What pathway does Windows use to send an open-file instruction to Foo? Does it go through the Main() method?
I've written Foo so only one instance of it will run at a time, so I need to be able to get Windows to tell the existing instance of Foo to open a file. Any ideas how this is done?
Thanks
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ok, but how do I get the previous instance then? These examples are all for preventing multiple instances. I think the 2nd one has some useful code that allows me to get the process object for the previous instance, but I can't seen to get the actual instance of the application (a winform object) from that process object, so I'm still kinda stuck. Any ideas?
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There are several approaches you can take
to transmit the command line info(such as
the filename) from the secondary instance of
your app to the primary. You can use sockets,
windows messaging, shared memory etc..
I did an ActiveX Control that uses a page
of the system swap file with a memory mapped
file to do it. It works with just about everything I've tried that can understand
ActiveX.
If you can read Delphi, the source to the
component that the ActiveX Control is derived
from is online. http://www.torry.net
Search on "TellTail" to download the Delphi source. Basically it uses a named mutex to determine if you're in the primary or secondary instance of the app. If in the secondary, it copies command line info to the shared memory page. The primary instance has to periodically check if any info has been put in shared memory then call a method to copy it out.
I'm reworking it now to use the 'Global\'
namespace if in XP for the named kernel objects
but I may also change it to use a system event
to eliminate the polling in the primary app.
When the next revision comes out I'll have to
decide how I'm going to distribute it. But
for now the Delphi source might give you some
ideas how to do it in C#.
Good luck.
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The first article I gave you does exactly what your talking about. All you have to do is examine the source code. There is also an article[^] on MSDN that demonstrates what you want to accomplish. There is a follow up article for that one that fixes a bug in the first article here[^].
RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome
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Sorry, I guess I wasn't being clear enough. Yeah, that article was doing what I wanted. The solution just seemed overly complex, and it was in VB (I'm using C#). Plus I'm writing an open source application, so I have to be careful what code I compile into my app.
At the time I didn't realise it would be so much work to have one instance of an application contact another - I figured it was just a case of getting the instance via its handle, which I now understand is not enough. Thanks for your help ... guess I'll be taking a closer look at that VB code after all.
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I am trying to take a screenshot of a window from its handle.
This is the code that takes the handle and get the image from it.
public Image gdiShot(IntPtr handle)
{
//get dc from handle
IntPtr sourceDC = USER32.GetWindowDC(handle);
//create the copy destination dc
IntPtr destDC = GDI32.CreateCompatibleDC(sourceDC);
//get dimensions of dc
USER32.Rect rect = new USER32.Rect();
USER32.GetWindowRect(handle,ref rect);
int width = rect.x2 - rect.x1;
int height = rect.y2 - rect.y1;
//create bitmap
IntPtr h_myImage = GDI32.CreateCompatibleBitmap(sourceDC,width,height);
//select bitmap object into destination device context
GDI32.SelectObject(destDC,h_myImage);
//time to blit
GDI32.BitBlt(destDC,0,0,width,height,sourceDC,0,0,0x00CC0020);
//cleanup
GDI32.DeleteDC(destDC);
USER32.ReleaseDC(handle,sourceDC);
Image myImage = Image.FromHbitmap(h_myImage);
return myImage;
}
Now this works, IF my windows style is set to the default blue,silver,or olive etc. However, I use a custom skin and I am not the only one. And when I run this code with the custom skin, I always end up having 3 extra lines of pixels on top of the image. In reality the window IS 3 pixels lower on the desktop then reported by GetWindowRect API call. At this point I was about to blame the skin, but I open SnagIt take the shot of the same window with custom skin and what do you know, no extra lines on top. In other words I know it is possible.
I am open to ANY suggestions. For ex: alternative API calls to use, a way to try and get the REAL visible coordinates of a window.
Also worth mentioning:
This only applies to windows with title bars. The device context sees the window as 500x500. In reality pasted into Photoshop its 500x497.
I get the window handle passed on to this functino from a mouse click, then GetWindowFromPoint, and then GetAncestor to get to the handle of the root window.
Any suggestions please, I'm desperate.
I've seen SnagIt do it  now I have to find a way to do it too, because I know its possible.
Anybody know a way to get titlebar height? 
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maybe the style is using regions ?
use GetWindowRgn API to check ..
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Right on target.
I just called that function and with the custom skin the output is 2 with the windows skin the output is 3. Unfortunately I do not know what exactly that means.
This is what MSDN says.
NULLREGION The region is empty.
SIMPLEREGION The region is a single rectangle.
COMPLEXREGION The region is more than one rectangle.
ERROR The specified window does not have a region, or an error occurred while attempting to return the region.
Ok thats nice, but the return type of the function is int. Go figure...
What effect would a region have. Im thinking the window is 500x500 but the reagion that allows to be painted in is smaller (the three pixel rows on top). Am I correct?
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And those are ints:
#define ERROR 0
#define NULLREGION 1
#define SIMPLEREGION 2
#define COMPLEXREGION 3
#define RGN_ERROR ERROR There's the values. In C/C++ pre-proc defs are almost always used in place of hard-coded values because they're much easier to change.
Download the Platform SDK from http://msdn.microsoft.com/platformsdk[^] and you can find these values. If you installed the Platform SDK with Visual Studio (a default option if you install VC++ as well), the headers are already present. These pre-proc defs are found in wingdi.h.
Microsoft MVP, Visual C#
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I just used the GetWindowRgnBox call and it solved my problem. Well you, hspc, solved my problem. Thank you!
Like I said in the previous post the painting region was ofset 3 pixels down from the actual dimensions of the window. I run this call with custom skin it return 3 for top part of the RECT structure. I run it with windows skin its 0. 
Thanks again.
And if you know what the return values for GetWindowRgn mean, please share. Because I suppose there could be more than one painting region, the program has to be able to react appropriately.
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Microsoft wrote:
 Although many of the filters provided with DirectShow support property pages, they are intended for debugging purposes, and are not recommended for application use. In most cases the equivalent functionality is provided through a custom interface on the filter. An application should control these filters programatically, rather than expose their property pages to users
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/directx9_c/directX/htm/introductiontodirectshow.asp
Does anyone know how to "control these filters programatically"? Or where can I find a sample or documentation on the topic?
Very appreciate for any kind of help. Thanks. 
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