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DARPA Delving Into the Black Art of Super Secure Software Obfuscation
coondoggie writes Given enough computer power, desire, brains, and luck, the security of most systems can be broken. But there are cryptographic and algorithmic security techniques, ideas and concepts out there that add a level of algorithmic mystification that could be built into programs that would make them close to unbreakable. That's what the Defense Advanced Research Projects Agency (DARPA) wants for a new program called "Safeware." From DARPA: “The goal of the SafeWare research effort is to drive fundamental advances in the theory of program obfuscation and to develop highly efficient and widely applicable program obfuscation methods with mathematically proven security properties.”
Well, something that is obscure is just something that's hard to read. A password is supposed to be hidden, and not seen at all. "Security through obscurity" is the idea that they'll be able to see your algorithms, just not figure it out.
That is the standard consensus view in the software industry, yes. I'm afraid to tell you though, that it's wrong.
Last year there was a mathematical breakthrough in the field of what is called "indistinguishability obfuscation". This is a mathematical approach to program obfuscation which has sound theoretical foundations. This line of work could in theory yield programs whose functioning cannot be understood no matter how skilled the reverse engineer is.
It is important to note here a few important caveats. The first is that iO (to use the cryptographers name) is presently a theoretical technique. A new paper came out literally 5 days ago that claims to discuss an implementation of the technique but I haven't read it yet. Will do so after posting this comment. Indeed, it seems nobody is quite sure how to make it work with practical performance at this time.
The second caveat is that the most well explored version of it only applies to circuits which can be seen as a kind of pure functional program only. Actually a circuit is closer to a mathematical formula than a real program e.g. you cannot write circuits in C or any other programming language we mortals are familiar with. Researchers are now starting to look at the question of obfuscating "RAM programs" i.e. programs that look like normal imperative programs written in dialects of, say, C. But this work is still quite early.
The third caveat is that because the techniques apply to pure functions only, they cannot do input or output. This makes them somewhat less than useful for obfuscation of the sort of programs that are processed with commercial obfuscators today like video games.
Despite those caveats the technique is very exciting and promising for many reasons, none of which have to do with DRM. For example iO could provide a unifying framework for all kinds of existing cryptographic techniques, and enable cryptographic capabilities that were hereto only conjectured. For example timelock crypto can be implemented using and iO obfuscator and Bitcoin.
Security through obscurity can work to a point. *IF* you make it hard enough.
Take for example Raiden II. That game has only recently (in the past month) been 'cracked'. Even though only sorta. There is no encryption. It is all just bundled into a 'cop' chip.
The point though with their 'security' was not to never be cracked. But just make it a big enough pain in the ass that the bootlegers didnt copy the game for a long time. You could argue it took nearly 20 years to crack. Not bad for security through obscurity.
The entire emulation scene is basically cracking all those systems. To them a badge of honor is to actually accurately emulate the 'security'.
With security it is *never* 100%. It is just a matter of time and money.
Even if I come up with something that 100% provably secure. I am not going to show you how it works. I am not going to make it in any way easier. The obscurity is not for the security. It is mostly to waste your time. If that takes long enough the message may longer be worth decoding.
Fortunately, Merriam Webster is not the final and complete authority on the connotations of words, nor on how they are used within specialized disciplines.
OK, I read the paper.
The money quote is at the end:
Translated into programmer English, a "16 bit point function" is basically a mathematical function that yields either true or false depending on the input. It would correspond to the following C++ function prototype:
bool point_function(short input);
In other words you can hide a 16-bit "password" inside such a function and discover if you got a match or not. Obviously, obfuscating such a function is just a toy to experiment with. "SHA256(x) == y" is also a point function and one that can be implemented in any programming language with ease - short of brute forcing it, there is no way to break such an "obfuscated point function". Thus using this technique doesn't presently make a whole lot of sense. However, it's a great base to build on.
I should note that the reference to AND gates above doesn't mean that the program is an arbitrary circuit - it means that the "program" which is being obfuscated is in fact a boolean formula. Now you can translate boolean circuits into boolean formulas, but often only at great cost. And regular programs can only be translated into circuits at also a great cost. So you can see how far away from practicality we are. Nonetheless, just last year the entire idea that you could do this at all seemed absurd, so to call the progress so far astonishing would be an understatement. Right now the field of iO is developing so fast that the paper's authors note that whilst they were writing it, new optimisations were researched and published, so there are plenty of improvements left open for future work.