3 ms·

I don't understand what is so hard to get right about the RNGs of these machines. Any of-the-shelf cryptographically secure random number generator should chea

I don't understand what is so hard to get right about the RNGs of these machines. Any of-the-shelf cryptographically secure random number generator should cheaply and efficiently do the trick. Seeding? Combine the current time from the RTC with a machine specific key programmed at the factory, and/or use a hardware RNG. Linux+openSSL does the job. In fact, my i386 from the 90's could do an adequate job. That's of the top of my head, without doing any research. Using an algorithm from Knuth for these things would be completely irresponsible. I must be missing something here, they can't be this grossly incompetent while gambling millions.

nonsince 7y ago
Presumably the fact that they video the machine shortly before using it means that they’re relying on the fact that the hardware randomness is low. They implied that it wasn’t 100% effective, simply effective enough to make their odds better than the house’s. In cryptography, `/dev/random` is preferred to urandom since it blocks when one doesn’t have enough randomness. The machine doesn’t have randomness sourced from user input between the videoing and the attack, so all it has is relatively-low-entropy randomness (at least, within a small timeframe) such as ambient heat. I could definitely believe that this is very hard to defend against without a dedicated hardware randomness source or blocking when entropy is low.
Traster 7y ago
While it's not difficult to use a good RNG it's quite likely that none of these machines have been significantly updated since they were first designed and when they were first designed they probably weren't thinking about attack vectors. The exploit isn't being able to crack incredibly well designed RNGs, the exploit is being able to crack crap RNG based machines without the casino or machine manufacturer noticing. Slot machines are a huge industry and no one thinks of them as an attack vector, so these guys can probably milk quite a bit of cash out of them without anyone ever noticing. Meanwhile the cost of fixing these machines is high - they're not going to be set up for OTA updates, so the manufacturer now has to spend probably 2 days changing the RNG, and the next 6 months delivering updates to all their customers and explaining to them that their slot machines were probably costing them several hundred thousand dollars.

nonsince 7y ago

Presumably the fact that they video the machine shortly before using it means that they’re relying on the fact that the hardware randomness is low. They implied that it wasn’t 100% effective, simply effective enough to make their odds better than the house’s. In cryptography, `/dev/random` is preferred to urandom since it blocks when one doesn’t have enough randomness. The machine doesn’t have randomness sourced from user input between the videoing and the attack, so all it has is relatively-low-entropy randomness (at least, within a small timeframe) such as ambient heat. I could definitely believe that this is very hard to defend against without a dedicated hardware randomness source or blocking when entropy is low.

Traster 7y ago

While it's not difficult to use a good RNG it's quite likely that none of these machines have been significantly updated since they were first designed and when they were first designed they probably weren't thinking about attack vectors. The exploit isn't being able to crack incredibly well designed RNGs, the exploit is being able to crack crap RNG based machines without the casino or machine manufacturer noticing. Slot machines are a huge industry and no one thinks of them as an attack vector, so these guys can probably milk quite a bit of cash out of them without anyone ever noticing. Meanwhile the cost of fixing these machines is high - they're not going to be set up for OTA updates, so the manufacturer now has to spend probably 2 days changing the RNG, and the next 6 months delivering updates to all their customers and explaining to them that their slot machines were probably costing them several hundred thousand dollars.