Re: FlushFinalBlock problem in my cryptography - C# Discussion Boards

FlushFinalBlock problem in my cryptography

13-Jan-04 5:43

I'm sorry, it is SecureCustomProperties. It probably won't exist in the MSI created from the Windows Installer proejct in VS.NET, so just add it and remember that it is a semi-colon-delimited list.

Mazdak12-Jan-04 10:28

12-Jan-04 10:28

I do an encryption with hashing and now try to check itfor myself so I show output of encyption in my console application ,then I replcae one of characters with another one to check changing the string and my hashing mechanism get it,for example replace 2 with 1.But in this situation I get run time error at the line which I use FlushFinalBlock() for my decryptor stream. Any suggestion?

Mazy

No sig. available now.

Heath Stewart12-Jan-04 10:37

12-Jan-04 10:37

Could you please post the exception text? This would be far more helpful than "run time error". Smile | :)

Mazdak12-Jan-04 22:36

12-Jan-04 22:36

Oh,Sorry,thats the things that I always say to others,now I gorget it myself.

This is an error message: Bad Data

This is an ecryption between web service and a client so I convert bytes to string,and it look like this:

232 121 32 45 23.....

For doing some test I replcae all 2 with 1 programically, but changing cause to this eeror at line I told, I write my IV at the begining of string maybe changing in that cause this,any idea?

Mazy

No sig. available now.

Heath Stewart13-Jan-04 2:50

13-Jan-04 2:50

You should be transfering this data as base64. See the FromBase64Transform and ToBase64Transform. There should also be some sample code in there, too. Basically, the plain text and cipher text is run through these transforms which encodes and decodes the data using base64 transforms. This is what most cryptographic providers use as an encoding when transferring cipher text. Converting bytes to strings like you are is not a standard encoding so the cryptographic transforms won't understand it.

Mazdak13-Jan-04 2:56

13-Jan-04 2:56

Thhanks Heath...Ok,I'll do it. But that error does not happend at regular time,it only happend if I change the some charachters inside my application.

Mazy

No sig. available now.

Heath Stewart13-Jan-04 3:00

13-Jan-04 3:00

If you're changing the cipher text it shouldn't decrypt. What's the point of encryption, then? Throwing an exception is what should be happening in some cases, and "Bad data" sounds about right. I got that once or twice when testing my XML Digital Signatures sample code to make sure that changing the signature digest invalidated the signature.

Mazdak13-Jan-04 4:02

Entering Text on an Image

13-Jan-04 4:02

Fair enough.

Mazy

No sig. available now.

JayTheK12-Jan-04 10:08

JayTheK

12-Jan-04 10:08

I am looking for a way to enter and edit text on an image displayed on a form. Any suggestions

Re: Entering Text on an Image

Niels Penneman12-Jan-04 10:14

Niels Penneman

12-Jan-04 10:14

Create a Graphics object (CreateGraphics) and use DrawString

greetz Wink | ;-)

*Niels Penneman*

Software/Dev Site
Personal Site

Object property with different return types

Articus12-Jan-04 7:13

Articus

12-Jan-04 7:13

I have a control 'MyControl' with a property of type 'MyObject'. MyObject has a property 'MyField' that is a enum type. I want the type of enum to vary depending on a another property of MyObject called 'MyFieldType'. E.g. if MyFieldType = TypeA, MyField returns EnumA. See code below:

public enum FieldTypes
{
TypeA,
TypeB
}

public enum EnumA
{
Big,
Medium,
Small
}

public enum EnumB
{
Short,
Tall,
Squat,
Huge
}

[DefaultProperty("MyFieldType")]
public class MyObject
{
private FieldTypes m_MyFieldType;
private object m_MyField = 0;

public FieldTypes MyFieldType
{
get {return m_MyFieldType;}
set {m_MyFieldType = value;}
}

public object MyField
{
get
{
if (MyFieldType == FieldTypes.TypeA)
{
return (EnumA)m_MyField;
}
else
{
return (EnumB)m_MyField;
}
}
set
{
m_MyField = value;
}
}
}

My problem is that the MyField property is not editable via a dropdown list in the designer. It appears as a greyed-out (read only) string representation of the respective enum (EnumA or EnumB). I've tried writing a TypeConverter (inheriting from EnumConverter) but just ended up going round in circles.

Does anyone have an example of what I'm trying to do or point me in the right direction?

Thanks

Re: Object property with different return types

leppie12-Jan-04 8:16

leppie

12-Jan-04 8:16

It is because you are returning object. That said, if you return an object from an encapsulting class, and apply the ExpandableObjectConverter, you should be able to access the "real" properties.

leppie ::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.

Re: Object property with different return types

Articus12-Jan-04 22:41

Articus

12-Jan-04 22:41

MyObject is already using the ExpandableObjectConverter that's not the problem. It's the MyField property. If I use an ExpandableObjectConverter for this property, the property becomes editable, but as a string not an enum. I think I need to use some kind of EnumConverter and dynamically specify the enum type, but I don't know how.

Re: Object property with different return types

leppie13-Jan-04 6:16

leppie

13-Jan-04 6:16

You wanna make a typeconvertor for the type and apply that. The key methods to override (implement) is SupportValues() and GetSupportedValuesCollection() (the method names are most likely wrong Poke tongue | ;-P

too lazy to look them up). This will automaticaly create an "enum" like convertor, do not implemeted any other methods.

leppie ::AllocCPArticle("Zee blog");
Seen on my Campus BBS: Linux is free...coz no-one wants to pay for it.

Refresh TreeView in Place

webdudeIA12-Jan-04 5:24

webdudeIA

12-Jan-04 5:24

What is the best way to update a treeview node in place?

I have a tree view that exposes the nodes to an XML editor. When the value of this node changes [in the XML editor], I' like to update the tree to show the new value.

Coding in the heartland

Re: Refresh TreeView in Place

Heath Stewart12-Jan-04 8:48

Re: Refresh TreeView in Place

12-Jan-04 8:48

There is no direct binding support such as this (though you could add support). Instead, watch the XML fragment/file for changes and update the node text. There are so many ways of doing this, however, that it'd be difficult to list them all here.

You could, for example, watch for any changes in your editor (like for a multi-line TextBox handle the TextChanged event). When it changes, rebuild your tree from the XML information in the TextBox. To update just the node who's representation has changed in the XML fragment/file, it would be much more difficult. You could construct a path by recursing up the parent elements and pre-pending the text each time, using the TreeView.PathSeparator to separate each node. Then use that to find the node in the tree and update only that TreeNode. This would get increasingly difficult for added and removed nodes because you would also have to take state into account. Most implementations I've seen simply refresh the tree, which is apparent for larger XML hierarchies.

webdudeIA12-Jan-04 10:17

webdudeIA

12-Jan-04 10:17

Thanks Heath.

Fortunately, for this application I won't have to worry about too many added or removed nodes.

I continued to play around with the functionality I was looking for. The combination of events that gives me the functionality I'm looking for is both KeyUp and Leave. But, I see that TextChanged would work just as well. Thanks.

I set a flag to manage the dirty state of my text box and this seems to work well even when I have a 6mb XML file loaded in the tree.

I was looking for the method that I use to update just a single node in place. As you said, "simply... refresh the tree". Thanks. That works fine.

Coding in the Heartland

Enumerations

Anonymous12-Jan-04 4:10

Anonymous

12-Jan-04 4:10

Hopefully one of you guys could help me with this query about enumerations.

Heres a simple enumeration :

public enum e {Val1=1, Val2=2 }

This allocates Val1 as int 1, Val2 as int 2 and so on, so if i do :

int x = (int) e.Val2;

x is given the value of 2

Now heres the thing, I want to allocate four int values, now I know this code isnt right but it gives an idea of the effect I am after :

public enum e {Val1="1,2,3,4", Val2="5,6,7,8"};

So if I use the following code :

int[] x = (int[])e.Val2

Which would populate the int array X with the values 5,6,7,8

Re: Enumerations

Colin Angus Mackay12-Jan-04 5:56

Colin Angus Mackay

12-Jan-04 5:56

Anonymous wrote:
public enum e {Val1="1,2,3,4", Val2="5,6,7,8"};

The reason this does not work is because enum is intrinsically an int.

Anonymous wrote:
int[] x = (int[])e.Val2

Even if e.Val2 returned a string this code would not work because it is not possible to directly convert a string to an array of ints.

An idea might be to set up an array of arrays that map to the enum:

public enum e{Val1 = 0, Val2=1}

// Maps to some array

int[] x = (int[])myArray[(int)e];

--Colin Mackay--

EuroCPian Spring 2004 Get Together[^]

Re: Enumerations

Niels Penneman12-Jan-04 5:58

Niels Penneman

12-Jan-04 5:58

That is absolutely not supported! No arrays, no strings, ... you'd get the following error:

Type byte, sbyte, short, ushort, int, uint, long, or ulong expected

Hmm however you can combine 2 int16s into an int32 and find the values by doing some bit manipulation (in a function you call to calculate the values based on the int32 of the enum) I think, but that is way too complicated...

Why would you want to do such thing anyway?

greetz Wink | ;-)

*Niels Penneman*

Software/Dev Site
Personal Site

Re: Enumerations

Heath Stewart12-Jan-04 8:38