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'[OT]: Java and C programs reverse engineering'
2002\02\22@145753 by Randy Poon

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Hello,

I heard somebody said, we can get back the source code from a Java executable
program easily by running some reverse engineering software. Is this true? Does
the same apply to the C Language? If so, our C programs will be highly
unprotected, which is something I don't want to see!

Thanks!

Randy



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2002\02\22@151248 by Mitch Miller

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On Fri, 22 Feb 2002, Randy Poon wrote:

> Hello,
>
> I heard somebody said, we can get back the source code from a Java executable
> program easily by running some reverse engineering software. Is this true? Does
> the same apply to the C Language? If so, our C programs will be highly
> unprotected, which is something I don't want to see!

You have to first obtain the object code / binary, but once you have that,
and know the type of processor it was compiled for, it could be reverse
engineered into source code again.  The ones I've seen won't necessarily
have the same code labels as in your original source, since many
(most) compiled binaries don't contain them.  That would not, however,
keep the decompiler from assigning arbitrary labels to points in code it
sees as being "called" or "jmp"ed to.

-- Mitch

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2002\02\22@152125 by Dale Botkin

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On Fri, 22 Feb 2002, Mitch Miller wrote:

> On Fri, 22 Feb 2002, Randy Poon wrote:
>
> > Hello,
> >
> > I heard somebody said, we can get back the source code from a Java executable
> > program easily by running some reverse engineering software. Is this true? Does
> > the same apply to the C Language? If so, our C programs will be highly
> > unprotected, which is something I don't want to see!
>
> You have to first obtain the object code / binary, but once you have that,
> and know the type of processor it was compiled for, it could be reverse
> engineered into source code again.  The ones I've seen won't necessarily
> have the same code labels as in your original source, since many
> (most) compiled binaries don't contain them.  That would not, however,
> keep the decompiler from assigning arbitrary labels to points in code it
> sees as being "called" or "jmp"ed to.

And I think the chances of getting readable, useful C or Java from
de-compiling code would be pretty slim.  There are a hundred different
ways to write the same thing in C...  well, a hundred in Perl, maybe a
dozen in C!  8-)  Disassembling is easy, decompiling would be hard.

Dale

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2002\02\22@153903 by David Koski

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On Fri, 22 Feb 2002 11:54:11 -0800
Randy Poon <spam_OUTrandy9caTakeThisOuTspamYAHOO.COM> wrote:

> Hello,
>
> I heard somebody said, we can get back the source code from a Java executable
> program easily by running some reverse engineering software. Is this true?
Does
> the same apply to the C Language? If so, our C programs will be highly
> unprotected, which is something I don't want to see!

Perhap this is a minor point, but Java does not compile to native code except
for very specialized compilers.  The compiled java code is protable to any
platform that has a virtual machine to run it on.  Of course, C is another
matter.

David

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2002\02\22@154248 by Mitch Miller

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On Fri, 22 Feb 2002, Dale Botkin wrote:

> And I think the chances of getting readable, useful C or Java from
> de-compiling code would be pretty slim.  There are a hundred different
> ways to write the same thing in C...  well, a hundred in Perl, maybe a
> dozen in C!  8-)  Disassembling is easy, decompiling would be hard.

Check this site out ... as ususal, it's someone's PhD thesis.
http://www.itee.uq.edu.au/~csmweb/dcc.html

-- Mitch

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2002\02\22@154254 by Francisco Ares

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I agree with you, Dale, a "decompiler" would produce a different but
working version of the original one.

Francisco


Dale Botkin wrote:

{Quote hidden}

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2002\02\22@155252 by Bob Ammerman

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Useful Java isn't all that hard because the variable and class names are
available in the .CLASS file.

Bob Ammerman
RAm Systems

{Original Message removed}

2002\02\22@155931 by Barry Gershenfeld

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>I heard somebody said, we can get back the source code from a Java executable
>program easily by running some reverse engineering software.

You have to be smart enough to be able to write the thing in the first
place, in order to be able to understand what the decompiler puts out!

>If so, our C programs will be highly
>unprotected, which is something I don't want to see!

It's scarier than that.  Did you know that in some parts of the world
people write programs and then actually give away the source?

;-) Barry

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2002\02\23@075808 by Peter L. Peres

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>I heard somebody said, we can get back the source code from a Java
>executable program easily by running some reverse engineering software.
>Is this true?  Does the same apply to the C Language? If so, our C
>programs will be highly unprotected, which is something I don't want to
>see!

Assuming that a disassembler (called decompiler) matched to the particular
compiler that was used exists (and not any disassembler), it is possible
to reconstruct the C source, or at least its functional equivalent in C,
minus the variable and function names. Evil tongues say that large
compiler manufacturers and/or third parties (not for PIC) have such tools
and somtimes 'recover' the source of concurrent's products.

However once the program is burned into a chip and the protection is set,
the code cannot be read back easily.

Peter

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2002\02\23@145504 by uter van ooijen & floortje hanneman

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> Assuming that a disassembler (called decompiler) matched to the particular
> compiler that was used exists (and not any disassembler), it is possible
> to reconstruct the C source, or at least its functional equivalent in C,
> minus the variable and function names.

If this is possible at all the result would also lack all macro definitions
and invocations, which might well render the result useless (at least it
would for most C programs I write).

Wouter van Ooijen
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