|
Hi
I'm doing a RSA project in which I have encrypt and decrypt functions that get a BigInteger value when called and return encrypetd or decrypted BigInteger value. I get the number to encrypt or decrypt from the user (from textbox) and send it to the proper function. This work good when the user entered numeric values in the text box but now I try to make it work for any string that the user gives (numbers, letters and special chars) so I need to convert the input string to a unique BigInteger value so I can decrypt and encrypt it properly. I tried to use UTF8 encoding and Ascii Encoding (convert the string to byte array, the byte array to biginteger and send the biginteger to the proper function). both didn't work well because I couldn't decrypt a message after encrypting it using the methods above and after I converted the bigniteger value back to string it just showed me alot of strange characters ("?" and sqaures). So how can I make it work and what's the best method to convert a string to an unique BigInteger?
(
My program works well when the input is "259327521" for example (I can encrypt and decrypt such inputs), however this doesn't work when the input has letters or special chars "hello this is secret message!" so what I tried to do is to convert this kind of string to the BigInteger (using UTF8 encoding and Ascii encoding) but with no success because I couldn't decrypt properly a cipher after encrypting it and also I got weird chars after trying to convert the BigInteger back to the string
)
thanks alot
|
|
|
|
|
Your process has 3 separate steps
1) Encoding/Decoding of string to byte array
2) Conversion of byte array to BigInteger and vice versa
3) Encryption/Decryption of BigInteger
Your will need to know which step or steps are giving an error to solve this problem.
Certainly ASCII encoding won't be suitable unless the input is restricted to characters codes below 128. UTF8 should be ok, but the test is the round trip conversion from string to byte array and back again.
BigInteger conversion from/to a byte array, presumably via the BigInteger(byte[]) constructor and the ToByteArray method, should be ok as well, but again don't assume anything and perform a few tests.
Do the same for the encrypt/decrypt cycle and then you should be in a much better position to move forward towards a solution.
Alan.
|
|
|
|
|
|
Most public key encryption algorithms work by encrypting a symmetric key (i.e. a large number) by the public key method (e.g. RSA), and then using that symmetric key to encrypt the stream. Encrypting the entire stream content is expensive and unnecessary.
|
|
|
|
|
I have a bunch of different structs that implement IMyType. I also have some more advanced structs that are essentially containers for x number of IMyType instances (they are not lists). They need to be iterated so I am implementing IEnumerable<IMyType>. At the moment I have made a custom enumerator that has a params IMyType[] myTypes parameter in the contructor and using this type of code in the IEnumerable structs:
public IEnumerator<IMyType> GetEnumerator()
{
return new MyTypeEnumerator(
new IMyType[] {
new MyType(...),
new MyTypeOther(...) });
}
This works fine but I've been considering getting rid of the MyTypeEnumerator and using this instead:
public IEnumerator<IMyType> GetEnumerator()
{
IEnumerable<IMyType> collection = new IMyType[] {
new MyType(...),
new MyTypeOther(...) };
return collection.GetEnumerator();
}
Obviously both work just fine and are pretty much identical. Which would you prefer?
Edit: Alternatively, I could just use return new MyTypeEnumerator(this); and let the MyTypeEnumerator take care of it. I don't like that idea - ignore
modified 27-Oct-12 10:19am.
|
|
|
|
|
You'd normally only create a custom enumerator if you want to be able to enumerate the (virtual) collection without holding the whole list in memory all at once. So I don't quite understand the purpose of your implementation. If you can define a list form for your object, why not just expose that?
public IList<IMyType> Items {
get {
IList<IMyType> list = new List<IMyType>();
list.Add(new MyType(...));
list.Add(new MyTypeOther(...));
return list;
}
}
public IEnumerator<IMyType> GetEnumerator() { return Items.GetEnumerator(); }
Actually you don't need to implement IEnumerable at all if you do that, you can put the List property on the interface and users can do foreach(IMyType item in myObject.Items) instead of foreach(IMyType item in myObject).
|
|
|
|
|
There is another class that has a method:
public void Send(IEnumerable<IMyType> collection)
{
foreach(IMyType myType in collection)
{
}
}
This is the only place the IEnumerable is used (no need for any sort of list at all), so that leaves the second method as the prefered, essentially what your list is doing but without the list.
|
|
|
|
|
But the point is you are creating the list anyway (well, an array to be precise, but it's pretty much the same thing). However, implementing only IEnumerable and not IList (or exposing a list) implies that the enumeration can be run without the whole thing being in memory all at once.
It would be cleaner to expose the list and to pass that to Send (i.e. instead of calling Send(myObject), call Send(myObject.Items), to my mind.
|
|
|
|
|
I see where you're coming from. Richard's solution below is the best for this particular situation I think as the array doesn't actually need to be in memory all at once. I can simply create the instances as required using yield return directly.
Thanks for your input though, it has helped clarify some of my thinking in regards to iterators and foreach which will be helpful in future, and encouraged me to dig deeper into the whole thing that I previously just took for granted 
|
|
|
|
|
Another alternative to consider:
public IEnumerator<IMyType> GetEnumerator()
{
yield return new MyType(...);
yield return new MyTypeOther(...);
...
}
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
|
|
|
|
|
Good thinking, much better creating the new IMyTypes as needed. 5d 
|
|
|
|
|
As was said earlier, there is not much reason to create a custom enumerator these days. The reason for an enumerator is to be able to use the ForEach loop. The Yield statement. Then there is also LINQ, Not sure why you are even bothering with an Enumerator given the alternatives avaialable.
|
|
|
|
|
Clifford Nelson wrote: there is not much reason to create a custom enumerator these days
That's why I asked, it felt somewhat unnecessary.
Clifford Nelson wrote: Not sure why you are even bothering with an Enumerator given the alternatives
avaialable
There are many types in the library that are responsible for creating multiple instances of the interface IMyType (the quantity and implementation differs by the type) when required, and all these types need to be able to be passed to one common method so it can iterate over the interface instances - IEnumerable<IMyType> fits this scenario/concept perfectly, what is was designed for IMO.
|
|
|
|
|
hey guys , i hav a dll file and i want to add this dll file in my c#.net project reference . i knw ,i can do this by simple clicking,copying and paste but i want to do this through a program.
pls help me
as i ma newbie.
thanks
|
|
|
|
|
References don't exist at runtime so you're question doesn't make any sense.
Are you talking about using this .DLL as a "plugin"?? You can try reading this[^].
|
|
|
|
|
prani_partner wrote: i hav a dll file and i want to add this dll file in my c#.net project reference . i knw ,i can do this by simple clicking,copying and paste but i want to do this through a program.
You can create macro's in Visual Studio, and yes, you can manipulate the IDE from code. However, when would this type of AddIn execute? Probably when the user initiates it, say, by clicking somewhere.
..or are you referring to the "using" group at the top of the file?
Bastard Programmer from Hell 
if you can't read my code, try converting it here[^]
|
|
|
|
|
|
I just made a very simple app.
Enter some numbers, click a button, program calculates a result.
I tried to build a "release" version.
Ugh.
I want a simple executable file where the user can click and it runs, without going through an installation procedure.
I have searched here and MSDN for...
"BUILDING A C# APPLICATION THAT DOES NOT HAVE TO BE INSTALLED"
... and I'm finding zero and a little bit less.
This is a simple practice program, 24 instructions, 75 lines total, all just click click and it puts a number on the screen.
What did I miss ? Please tell me this can be done. I want to show my boss that I am capable of doing something; if only a simple thing.
|
|
|
|
|
- Code and debug the app.
- Switch the configuration to "Release" and rebuild.
- Give the app's release mode
.exe to your boss to run.
/ravi
|
|
|
|
|
Actually all you have to do is go into the bin\Debug (or what ever folder you want), and pick up the exe from there. The pdb file contains the debug information, and you can actually attach to the process and debug with the pdb containing the symbols.
|
|
|
|
|
C-P-User-3 wrote: What did I miss ? Please tell me this can be done.
All applications have dependencies, and .NET application depend on the correct .NET framework to be installed. We're not talking about native code here that you compile, but some kind of portable executable.
If you target-machine has all the prerequisites (correct .NET framework, various service packs) then you could do a simple xcopy and move the executable, as noted by the others.
Bastard Programmer from Hell
if you can't read my code, try converting it here[^]
|
|
|
|
|
I have been working on a WPF application and looking for the best way to implement the 'Ok' and 'Cancel' button click functionality in the modal dialog boxes.
The question has two parts:
Part -1:
Currently, I am doing it by creating a copy/clone of the actual object whenever we load the dialog. Later, I perform all the operations on the cloned object in the Modal dialog. If user press 'Ok', i'll assign all the values in the clone object to the actual object. If user press 'Cancel, i'll discard the cloned object and set it to null.
For E.g:
Suppose, I have a class Person
<pre lang="c#">
Class Person
{
public string FirstName {get; set;}
public string LastName {get; set;}
}</pre>
I have another class which holds the list of 'Person'
Class PersonContainer
{
public List<Person> Persons{get; set;}
}
We have a Window class 'PersonViewModel' which has all the things with respect to the view. This class has a ObservableCollection which is bound to a Datagrid in my View and properties 'FirstName and LastName' are bound to the columns of the Datagrid.
The view contains button to 'Add/Remove/Modify' the records and 'Ok' and 'Cancel' button.
suppose we have PersonContainer object 'originalContainer' with 2 records. In the load event of the view, we create a copy/clone of PersonContainer with 2 records. Let's call it as clonedContainer. When we perform any operation(Add/Remove/Modify) through the dialog, we do it on clonedContainer. Once, we are done, on press of 'Ok' button, we just update originalContainer with the clonedContainer. On press of 'Cancel', we discard the 'clonedContainer' and set it to null.
Q: what could be the best way to handle 'Ok' and 'Cancel' in a dialog? Is creating a cloned object right way?
Part 2:
I have to implement the undo/redo of all the actions(Add/Remove/Modify the record) that happened on the Dialog. This has been implemented through the ICommand pattern with Execute/Unexecute methods. Whenever, we add a record, we add it the through the Execute method. However, we use the clonedContainer object and not the real one. In the Unexecute, I am using the 'originalContainer' instance and remove the added Person object. Now, if we perform 'Redo', we need to create the removed 'Person' object. By this time, clonedContainer is no more as it has been destroyed once we close the dialog.
Q: How can we implement undo/redo here?
Thanks in advance!!!
Rags
|
|
|
|
|
I don't know why you cloned the object, if the collection keeps the current record, you can save the index of it and if cancel is clicked, remove from the collection and only save when the save button is click, here is a small sample, just play with this and see if it can help you.
1-You need to implement commanding in your project (you are already doing it)
2-in your view
link you button to a command in your viewmodel
Example a Save button:
4-remember your imports, this way you can display on the view the message for the user to answer and don't need to clone.
|
|
|
|
|
Thanks for the response!
Here I have used Person, PersonContainer and PersonViewModel just for representation. In actual scenario, the object is complex which updates many of its properties on Addition/modification of items in the datagrid. So, saving the index won't serve the purpose as we need the actual values.
Can you elaborate more on the 'imports' mentioned on #4? Still, i believe we need to clone the actual object and work on it. Appreciate, if you can help me a little detailed code.
- Rags
|
|
|
|
|
Rags1512 wrote: Q: what could be the best way to handle 'Ok' and 'Cancel' in a dialog? Is creating a cloned object right way?
There is no "right" way, there are only efficient, inefficient and non-compiling implementations. FWIW, I'm doing something similar; I clone the object and throw it in a PropertyEditor. Has a third button that says "reset" that simply clones the original again and uploads it anew in the PropertyEditor. Works well, doesn't have much overhead.
Rags1512 wrote: Q: How can we implement undo/redo here?
An undo/redo is usually limited to the form where one is editing. You'd need the Memento-pattern, saving the internal state of the object every time the user performs an action. Undoing the action is then as simple as fetching the internal state from that point.
Bastard Programmer from Hell 
if you can't read my code, try converting it here[^]
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
