4 ms·
"50% easier than theoretically impossible" means it's now 50% possible, doesn't it?
by talaketu 8y ago
"50% easier than theoretically impossible" means it's now 50% possible, doesn't it?
- Dylan16807 8y agoNo more than "half of infinity" is half finite.
- TylerE 8y agoInfinity and "practically infinity" aren't the same thing though. Half of "practically infinity" may end up being practical.
- krferriter 8y agoYes the previous value was not infinity. It was impractical to solve in a human lifetime, but if they keep trimming off a few bits it very quickly becomes practical. If actually "infinity" then dividing it by any finite number would still result in infinity, which is not the case here.
- geofft 8y agoRight, which is why the specific claim here is that 63 is not a problem, not that smaller numbers in general are not a problem. A better way to put this: instead of saying "it reduces the search space by 9 quintillion," say "it reduces 50% of the search space." Sure, that's a lot, but not nearly as much as trimming 8 bits and saying "it reduces 99.6% of the search space."
- saagarjha 8y ago> trimming off a few bits i.e., reduce it by close to practically infinity?
- Dylan16807 8y agoThere should be a very large gap between "theoretically impossible" and "practical". If cutting the search space in half gets you from one to the other, there's probably been an error in definition.
- TylerE 8y agoWho knows what the future would bring? A $32 million (1985 dollars) Cray 2 super computer could do 1.9GFlops. You can now get over 50x that performance for less than a grand in a device that fits in your pocket. I bet those engineers didn't expect that in half a lifetime.
- geofft 8y agoMoore's law was described in 1965 and the experimental evidence lined up for well past the next two decades. If you handwave exactly what it means to "everything is 2x better every 1.5 years," we'd expect a factor of 2^(30 / 1.5) = 1 million by 2015, so having a factor of 100,000x in cost and having it fit in your pocket wasn't actually unexpected. Certainly any cryptosystems designed in 1985 that wanted to encrypt data until today should have taken the most aggressive form of Moore's Law into account.
- dodobirdlord 8y agoThat's rather beside the point. If 63 bits is insecure, then 64 bits is also insecure. If I can brute force 63 bits in a week, I can brute force 64 bits in 2 weeks. If we are worried that 63 bits is a security issue, then the solution isn't increasing to 64 bits, it's increasing to 96 bits, or 128 bits.
- isostatic 8y agoI’ll worry about that next time I issue a 30 year certificate.
- ethbro 8y agoNassim Taleb would probably disagree. ;)
- ClassyJacket 8y agoNope, the chance of success for each attempt went from 1 in 18,000,000,000,000,000,000 to 2 in 18,000,000,000,000,000,000.
- talaketu 8y agothat's from theoretically possible to theoretically possible.
- Spare_account 8y agoWhich is grammatically consistent with the assertion that fundamentally nothing has changed: certificates with a 63-bit serial number are unlikely to be compromised and certificates with a valid 64-bit serial number are also unlikely to be compromised.
- Cthulhu_ 8y agoNot 1 in 18 quintillion to 1 in 9 quintillion? I think you've got your binary math wrong.
- matmg 8y ago2/18000000000000000000 == 1/9000000000000000000
- ClassyJacket 8y ago2/18 and 1/9 are equal.