Re: C# decompilation - C# Discussion Boards

peterchen12-Apr-07 5:05

peterchen

12-Apr-07 5:05

Original variable names are still required for reflection to work, Additionally, all (non-private/internal) entity names are required for the way the CLR finds external references. The one thing that could be "removed" are scope-local variables, but that won#t help a lot, andobfuscatorsa can do this.

I fully understand your concern, I need to keep this in mind permanently when deciding which technology for which product. But that's a tradeoff that in most cases makes sense.

There are two main ways to deal with code to protect:

* use an obfuscator
* move critical code to an unmanaged binary
* Reflection.Emit

All are not "complete": obfuscators seem a delicate balance between making the code unreadable and breaking it. External binaries, beisdes the old "find that DLL" problem, would still isolate the critical part and make reverse engineering the easier. Reflection.Emit could be used as addiitonal "obfuscation of ideas", but doesn't protect the code from being copypasted.

IIRC upcoming Authenticode features are supposed to provide a new mechanism that gives you control over who sees what. (I am not sure though, how well it is received or protects, as it sounds to much like DRM)

But keep in mind that every binary is reverse engineerable, it's just a quesiton of skill and patience.

We are a big screwed up dysfunctional psychotic happy family - some more screwed up, others more happy, but everybody's psychotic joint venture definition of CP
My first real C# project | Linkify!|FoldWithUs! | sighist

Christian Graus12-Apr-07 0:47

12-Apr-07 0:47

There's a number of reasons for this. At the core, the fact is that most people are targetting markets that do not contain people likely to decompile code. Having your code compile on the target machine opens the door to things like a version of the framework that optimises for new processors, such as dual cores or 64 bit. It also means that in theory the framework can target multiple architectures.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

Ed.Poore12-Apr-07 0:54

Ed.Poore

12-Apr-07 0:54

Christian Graus wrote:
It also means that in theory the framework can target multiple architectures.

What do you mean in theory? What about Mono? Poke tongue | ;-P

Doesn't that run on most Linux systems which run on most processors?

Christian Graus12-Apr-07 1:24

12-Apr-07 1:24

Isn't Mono not allowed to impliment the Windows.Forms classes ?

Ed.Poore12-Apr-07 1:30

Ed.Poore

12-Apr-07 1:30

From what I understand they are allowed but things at the moment are so tied down to Microsoft's way of things that they implemented stuff on GTK because a it was easier and b provided more flexibility (GTK was more established on different platforms and had more flexibility I think). I've got a feeling that they may have simply mapped the critical Windows.Forms to the GTK namespace.

You can from what I remember of my experimentations run most Windows.Forms apps on Mono without any adjustment but there are a few classes etc which are deeply tied into MSs way of things that they don't run. (Yet again) from what I remember the comments were that yes there are some problems with simply copying and pasting code across but there are some quite straightforward workarounds which will work in both Mono & MSs implementation so as long as you know of these before hand you should be OK.

Of couse most people writing for Mono use the GTK etc implementations because they're more used to coding to those in C++ etc and they're stuck in their ways.

But as far as I know there isn't a legal reason why Mono can't implement the Windows.Forms classes.

hairy_hats12-Apr-07 1:33

hairy_hats

12-Apr-07 1:33

I understand that, but for a release build to contain the original variable names is just daft. Why not do a compile-time replacement of the names with the shortest possible names to at least obfuscate your code and make the IL version as short as possible?

Christian Graus12-Apr-07 1:52

12-Apr-07 1:52

to create work for people writing obsfucators, of course.

Decompilation is very useful, for example, if you need to see what the framework is doing. You don't get the source like you did for MFC, but with a decompiler, you do.

hairy_hats12-Apr-07 3:02

hairy_hats

12-Apr-07 3:02

Christian Graus wrote:
to create work for people writing obsfucators, of course.

Not only does it let you see what the framework is doing, it also lets your customers see what you are doing. Suppose you are charging for the interface software to some proprietary hardware - with C# your customers can see exactly how the interface works and write their own for free. Goodbye revenue stream!

This has put me off using C# for any serious work that I will be sending to customers. I think I will be sticking with C++ and MFC for the foreseeable. Sigh | :sigh:

Pete O'Hanlon12-Apr-07 4:09

Pete O'Hanlon

12-Apr-07 4:09

Steve_Harris wrote:
This has put me off using C# for any serious work that I will be sending to customers. I think I will be sticking with C++ and MFC for the foreseeable.

Why? Unless you are doing serious reflection, there are ways round this using tools like Obfuscators.

Deja View - the feeling that you've seen this post before.

hairy_hats12-Apr-07 5:18

hairy_hats

12-Apr-07 5:18

Why should I have to buy one just to protect my IP? If I compile a C++ program it is immediately pretty well protected.

Pete O'Hanlon12-Apr-07 9:17

Pete O'Hanlon

12-Apr-07 9:17

Steve_Harris wrote:
Why should I have to buy one just to protect my IP? If I compile a C++ program it is immediately pretty well protected.

But not bulletproof. While it is protected better, it still isn't totally foolproof. All code is capable of being reversed.

Deja View - the feeling that you've seen this post before.

Christian Graus12-Apr-07 10:38

12-Apr-07 10:38

Steve_Harris wrote:
it also lets your customers see what you are doing

Sure, if you have the sort of customers who would be inclined to look.

Steve_Harris wrote:
I think I will be sticking with C++ and MFC for the foreseeable

The obvious alternative is to write C++ DLLs that hide your proprietary stuff and call them from C#.

AlwiNus14-Apr-07 12:34

AlwiNus

14-Apr-07 12:34

Christian Graus wrote:
The obvious alternative is to write C++ DLLs that hide your proprietary stuff and call them from C#.

What about C++/CLI? Isn't that managed and unmanaged code in the same assembly?

(Just curious... Big Grin | :-D

)

-alwinus

Christian Graus14-Apr-07 13:39

14-Apr-07 13:39

C++/CLI is managed code, so it also can be decompiled. It can be a combo of both, but the unmanaged part is the only way to write stuff that can't be decompiled.

BindingList

mark_w_11-Apr-07 23:43

mark_w_

11-Apr-07 23:43

I have 2 binding lists (say A and B), i need to compare the contents of A to B to see if they conatin the same items.

How can i do this?

Re: BindingList

Jaiprakash M Bankolli12-Apr-07 0:35

Jaiprakash M Bankolli

12-Apr-07 0:35

You will find good number of information on the following site

http://www.thescripts.com/forum/thread231103.html

Regards,
Jaiprakash M Bankolli
jaiprakash.bankolli@gmail.com
http://jaiprakash.blog.com/

Xml file [modified]

7111-Apr-07 23:17

11-Apr-07 23:17

hi,
I am saving some content in an XML file and and i am passign a XMl file name as a parameter to some function..

if i give normal file name it is creating a XML file.

but if I give some extra charcters like this in a file name &,",' it is giving error like below

"The & character,hexadecimal vale 0x26 can't be included i a filename"

is there any way to handle extra chracters.
pls help me.

-- modified at 5:22 Thursday 12th April, 2007

Christian Graus11-Apr-07 23:32

11-Apr-07 23:32

71 wrote:
The & character,hexadecimal vale 0x26 can't be included i a filename"

The error is correct. Try to create a file with that name in the file system and you'll find it's a limitation of windows. In fact, that's a good way to get a list of characters you need to remove or not allow in your filenames.

blackjack215011-Apr-07 23:59

blackjack2150

11-Apr-07 23:59

Well, actually '&' is a legal character in a Windows filename.
Illegal characters are: '/', '\', ':', '*', '?', '"', '<', '>' and '|'.

7112-Apr-07 0:06

12-Apr-07 0:06

hi,

but how can I handle those extra chracters like

if & replace with &
if " replace with "

help me pls

7112-Apr-07 0:46

12-Apr-07 0:46

hi,
foreach (char c in FileName)
{
switch (c)
{
case '&':
FileName = FileName.Replace("&", "&");
//"<","&"
break;
case '>':
FileName = FileName.Replace(">", ">");
break;
case '<':
FileName = FileName.Replace("<", "<");

break;
case '"':
FileName = FileName.Replace("\"", """);
break;
case ' ':
FileName = FileName.Replace(" ", " ");
break;
case '@':
FileName = FileName.Replace("@", "@at");
break;

see the code i am replacing the exttra charcters like this but still i am gettign error.

Christian Graus12-Apr-07 0:51

12-Apr-07 0:51

This code is way too messy, the string.Replace method will do this much nicer.

What's the error you're getting, and what's the filename ?

7112-Apr-07 0:59

12-Apr-07 0:59

hi,

i am giving file name as G&avi this is in somevariable var1;

forexch(char c in var1)
{
switch(c)
{
strifn newname="";
case '&':
newname=var1.replace("&","&");
break;

}

}
(i am replacing a & with @amp;)
)

Christian Graus12-Apr-07 1:48

12-Apr-07 1:48

71 wrote:
forexch(char c in var1)
{
switch(c)
{
strifn newname="";
case '&':
newname=var1.replace("&","&");
break;

This is ridiculous. All you need is the replace statement ( although this particular one does nothing, it replaces & with &.