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UCLA computer grad constructs “crown jewel of cryptography”

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Re: UCLA computer grad constructs “crown jewel of cryptography”

#51

Post by User23 »

grayhatter wrote: post #28
scarmig wrote: post #18

Earlier quoted context omitted.

Can't finite iteration and recursion just be unrolled? And storage just considered another part of the input?

In theory? Absolutely; unrolling a loop is exactly what it sounds like. Recursion is just a fancy loop. But there's a reason no one does that, and why no compilers emit that as code.

Fancy in the sense of being a loop with an implicit stack. Or maybe just some registers if TCO.

And yet the machines we can actually build are far closer to LBAs than TMs.

Re: UCLA computer grad constructs “crown jewel of cryptography”

#53

Post by yjftsjthsd-h »

Vervious wrote: post #34
hgsgm wrote: post #13

Earlier quoted context omitted.

Obfuscation is itself a malware signature.

I mean, the same argument has been applied to other cryptographic tools. Why encrypt your messages, unless you're sending something sketchy? Why obfuscate programs, unless you're hiding something? Yet I think the utility of encryption is well-demonstrated, and not just theoretical. It can be used by good people to defend against adversarial intent. And it may well be that obfuscation (in its most direct application)…

> I mean, the same argument has been applied to other cryptographic tools. Why encrypt your messages, unless you're sending something sketchy? Why obfuscate programs, unless you're hiding something?

It's easy to argue that everyone has legitimate interest in hiding some things in data, but what would be a legitimate case for hiding things in code?

Re: UCLA computer grad constructs “crown jewel of cryptography”

#54

Post by anonymousDan »

x-complexity wrote: post #41
Animats wrote: post #12

Earlier quoted context omitted.

I'm not sure. It seems to be applied to "circuits", which in this context seems to mean a one-way set of logic gates (such as AND, OR, NOT, NAND) which map a set of boolean inputs to a set of boolean outputs. In theory you can construct any finite digital function that way. It's a useful abstraction, like a Turing machine. Unlike a Turing machine, a circuit is finite. All circuits are "solveable" (given a outputs, co…

IMO: Paranoid about the implications, slightly less worried about it applying in practice. As shown by the DRM schemes used in modern games, this type of obfuscation comes at the cost of performance: Unless you want to compute a sensitive function at the user's end in an obfuscated manner, it'd be much simpler to just run that function on your end and optimize it in terms of running costs & performance. Such a design…

Would it be possible to use this to obfuscate other cryptographic primitives (e.g. a hash function or a simple program that checks whether the hash of some input equals a hardcoded value)?

Re: UCLA computer grad constructs “crown jewel of cryptography”

#55

Post by Retr0id »

Sophistifunk wrote: post #29

If mankind can't stomach 10% overhead to check array bounds and collect unused memory, what makes anybody think they can sell 1,000,000% overhead to make your DRM driver (and viruses) harder to reverse?

We already accept something on the order of 1000% overhead for video DRM (software vs hardware decoding)

Re: UCLA computer grad constructs “crown jewel of cryptography”

#56

Post by Retr0id »

Vervious wrote: post #40
yalogin wrote: post #38

DRM implementations already use code obfuscation heavily. Can someone with knowledge of the math clarify why this is a big deal? Why would it matter that there is mathematical proof that someone cannot figure out what the code is doing? How does it apply to crypto?

The code obfuscation that DRM implementations use is not provably secure. I don't think anyone would (or should) hide a bitcoin secret key inside of an obfuscated program. There's no formal guarantee of security. This work, on the other hand, shows a provably secure construction for obfuscation (assuming that some assumptions about the hardness of various well-studied mathematical problems are true). In other words,…

> I don't think anyone would (or should) hide a bitcoin secret key inside of an obfuscated program.

I can't remember where I read this, or if it was just a hypothetical, but I think I heard of people doing this deliberately as a sort of canary. If the wallet gets drained, then you know someone cracked your obfuscation.

Re: UCLA computer grad constructs “crown jewel of cryptography”

#57

Post by tivert »

dmix wrote: post #31
Animats wrote: post #12

Earlier quoted context omitted.

I'm not sure. It seems to be applied to "circuits", which in this context seems to mean a one-way set of logic gates (such as AND, OR, NOT, NAND) which map a set of boolean inputs to a set of boolean outputs. In theory you can construct any finite digital function that way. It's a useful abstraction, like a Turing machine. Unlike a Turing machine, a circuit is finite. All circuits are "solveable" (given a outputs, co…

The next question is why didn’t the high end shops spending a ton of money and recruiting effort on crypto and state malware like NSA .. or Russia(?) figure this out already or did they

> The next question is why didn’t the high end shops spending a ton of money and recruiting effort on crypto and state malware like NSA .. or Russia(?) figure this out already or did they

There's no way to know. But the NSA (at least) has a documented history of making crypto breakthroughs and keeping them secret (e.g. public key crypto: https://en.wikipedia.org/wiki/Public-key_cryptography#Classi..., differential cryptanalysis: https://en.wikipedia.org/wiki/Differential_cryptanalysis#His...).

Re: UCLA computer grad constructs “crown jewel of cryptography”

#58

Post by anonymousDan »

Vervious wrote: post #40
yalogin wrote: post #38

DRM implementations already use code obfuscation heavily. Can someone with knowledge of the math clarify why this is a big deal? Why would it matter that there is mathematical proof that someone cannot figure out what the code is doing? How does it apply to crypto?

The code obfuscation that DRM implementations use is not provably secure. I don't think anyone would (or should) hide a bitcoin secret key inside of an obfuscated program. There's no formal guarantee of security. This work, on the other hand, shows a provably secure construction for obfuscation (assuming that some assumptions about the hardness of various well-studied mathematical problems are true). In other words,…

How does obfuscating a key differ from encrypting it?

Re: UCLA computer grad constructs “crown jewel of cryptography”

#60

Post by moring »

Vervious wrote: post #34
hgsgm wrote: post #13

Earlier quoted context omitted.

Obfuscation is itself a malware signature.

I mean, the same argument has been applied to other cryptographic tools. Why encrypt your messages, unless you're sending something sketchy? Why obfuscate programs, unless you're hiding something? Yet I think the utility of encryption is well-demonstrated, and not just theoretical. It can be used by good people to defend against adversarial intent. And it may well be that obfuscation (in its most direct application)…

> I mean, the same argument has been applied to other cryptographic tools. Why encrypt your messages, unless you're sending something sketchy? Why obfuscate programs, unless you're hiding something?

There is a huge difference: Encryption is used to hide something from a third party, while obfuscation is used to hide something from the intended recipient.

Or, if you'd like to argue that the intended recipient is the computer, not the user: To turn that computer into a deputy of the sender, while still formally belonging to the recipient.

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