What types of executables can be decompiled?

Question

I think that java executables (jar files) are trivial to decompile and get the source code.

What about other languages? .net and all?

Which all languages can

Answer 1

Most languages can be decompiled but some are easier to decompile than others. .Net and Java put more information about the original program in the executables (method names, variable names etc.) so you get more of your original information back.

C++ for example will translate variables and functions etc. to memory adresses (yeah I know this is a gross simplification) so the decompiler won't know what stuff was called. But you can still get some of the structure of the program back though.

Answer 2

VB6 if compiled to pcode is also possible to decompile to almost full source using P32Dasm, Flash (or actionscript) is also possible to decompile to full source using something like Flare

Answer 3

In general, languages like Java, C#, and VB.NET are relatively easy to decompile because they are compiled to an intermediary language, not pure machine language. In their IL form, they retain more metadata than C code does when compiled to machine language.

Technically you aren't getting the original source code out, but a variation on the source code that, when compiled, will give you the compiled code back. It isn't identical to the source code, as things like comments, annotations, and compiler directives usually aren't carried forward into the compiled code.

Answer 4

Managed languages can be easily decompiled because executable must contain a lot of metadata to support reflection.
Languages like C++ can be compiled to native code. Program structure can be totally changed during compilation\translation processes.
Compiler can easily replace\merge\delete parts of your code. There is no 1 to 1 relationship between original and compiled (native) code.

Answer 5

.NET is very easy to decompile. The best tool to do that would be the .NET reflector recently acquired by RedGate.