I would like to encode code in such a way that each compilation
produces "random" code as compared to what the previous
compilation produced, but ultimately the same code is ran each
Basically we can code a function that does a job X in many
different ways. Each way looks different in binary but does the
same job(Same effect). I'd like a way to sort of randomly
sample/generate the different functions that do the same job.
The easiest way to wrap your head around this is to realize that
certain instructions and groups of instructions can be
rearranged, producing a binary that is different but the effect
is the same. Probably, ultimately, that is all that can be
done(certain other tricks could possibly be added to increase the
sampling coverage such as nop like instructions, dummy
The main issue is how to take an actual D function and transform
it in to a new D function, which, when ran, ultimately does the
same thing as the original but is not the same "binary".
Encrypting is a subset of this problem as we can take any string
and use it to encode the code then decrypt it. And this may be
usable, but then the encryption and decryption instructions must
somehow be randomizable, else we are back at square one. It might
be easier though, to use the encryption method to randomize the
original function since the encryption routine is known while the
original function is not(as it could be any function).
I'm not looking for a mathematical solution, just something that
works well in practice. i.e., The most skilled human reading the
disassembly would find it very difficult to interpret what is
going on. He might be able to figure out one encryption routine,
say, but when he sees the "same code"(same effect) he will have
to start from scratch to understand it because its been
The best way I can see how to do this is to have a list of well
known encoding routines that take an arbitrary function, encrypt
it. Each routine can be "randomized" by using various techniques
to disguise it such as those mentioned earlier. This expands the
list of functions tremendously. If there are N functions and M
different ways to alter each of those functions then there are
N*M total functions that we can use to encrypt the original
function. If we further allow function composition of these
functions, then we can get several orders of magnitude of
complexity with such as a few N.
The goal though, is to do this efficiently and effectively in a
way that can be amended. It will be useful in copy protection and
used with other techniques to make it much more effective.
Ultimately the weak point with the encryption techniques is
decryption the functions but by composing encryption routines
makes it stronger.
Any ideas how to achieve this in D nicely?