4 ms·
AFAIK GPUs are far more cost effective. I've just produced this estimate. 2xAMD 7970 : 8000Mhash/s ~= 2^33 Seconds per year ~= 2^24 Total Hashes ~= 2^57
by notaddicted 14y ago
AFAIK GPUs are far more cost effective. I've just produced this estimate.
2xAMD 7970 : 8000Mhash/s ~= 2^33
Seconds per year ~= 2^24
Total Hashes ~= 2^57
1kW * $0.15/kWh * 1 year ~= $1315
Rig cost (guess) ~= $2000
Total cost ~= $3315
Price for 2^60 hashes in a year:
2^60 / 2^57 * $3155 ~= $25000
If you assume a 6X discount in 2021, then it will be <5k. Still, it takes a year, or more money for machines. Corrections welcome. Trying to run sixteen 7970s for a year straight is probably a total crap shoot.
The hash rate is from http://www.codinghorror.com/blog/2012/04/speed-hashing.html http://www.codinghorror.com/blog/2012/04/speed-hashing.html .
[EDIT: I wouldn't be shocked if FPGAs could do it with 1/10th the power and heat, with the same variable cost (hardware & power) but with an additional fixed cost to build the devices; I'm basing this estimate on bitcoin mining boards like these:
https://en.bitcoin.it/wiki/Mining_hardware_comparison https://en.bitcoin.it/wiki/Mining_hardware_comparison ]
- thechut 14y agoI think this is the correct way to look at. a CPU is vastly slower at performing rainboow attacks than a GPU. Many of the largest bitcoin rigs could probably find a SHA-1 collision in a matter of months.
- notaddicted 14y agoYeah, I haven't made any provision for the other calculations required by the attack, so maybe those take a lot of resources, maybe they don't.
- matthew-wegner 14y agoThe combined network hashrate of Bitcoin is currently right around 20,000Ghash/s: http://bitcoin.sipa.be/ http://bitcoin.sipa.be/ Which is about 2,500X the processing power of an AMD 7970. Bitcoin is hashing SHA256, which is about as computationally expensive as SHA-1 (or maybe even cheaper, according to comments on the linked blog post). Much of the Bitcoin computational power comes from large mining operations controlled by individuals. Their processing power is easily diverted elsewhere, if the profit motive is there...
- kzrdude 14y agoAt current BTC price (~$12/BTC), mining generates 50 BTC every 10 minutes which translates into $1 value per second, or $1 for 20,000 GHash.