Re:1Password GPU brute-force with 3M hash/s
by mtgx on Tuesday April 16, 2013 @05:49PM
(#5561140)
Could the 66 Ghash/s Bitcoin ASIC's be easily repurposed for password cracking? It's something I've been wondering about.
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Re:1Password GPU brute-force with 3M hash/s
by alanctgardner2 on Tuesday April 16, 2013 @05:59PM
(#5561217)
When you get into ASICs (Application Specific Integrated Circuits), the answer to 'can it be repurposed?' is almost universally no. It's basically a purpose built circuit, built into a single package. This is cheap and fast, because you only put in the parts you need, but there's non-trivial engineering effort to design them.
I think initially some miners used FPGAs: these are reprogrammable and offer similar performance, but they're much more expensive.
Re:1Password GPU brute-force with 3M hash/s
by quinndupont on Tuesday April 16, 2013 @06:14PM
(#5561284)
I think ajross is (mostly) right, ASICs can be re-purposed for SHA256 calculations. To what extent they have baked in a whole round of SHA256 is a good question, they may just be developed around very parallel XORs (which is why some GPUs are faster at BTC mining than others—they have built in XOR logic).
I do believe seeing that (the mythical) Butterfly Labs intends on releasing software for all sorts of other parallel high-performance applications (or some kind of driver/API type of thing), but I could be hallucinating.
Re:1Password GPU brute-force with 3M hash/s
by sliverstorm on Tuesday April 16, 2013 @06:16PM
(#5561301)
I think ajross is (mostly) right, ASICs can be re-purposed for SHA256 calculations.
I know what you mean, but I think you should be more specific in your statement. Bitcoin mining ASICs might be re-purposable. Not all ASICs.
Re:1Password GPU brute-force with 3M hash/s
by quinndupont on Tuesday April 16, 2013 @06:18PM
(#5561316)
Good point. An ASIC could be completely non-repurposable. The commonly-available (soon) BTC ASICS should be damn good at SHA256 cracking, maybe other XOR-related applications too.
Re:1Password GPU brute-force with 3M hash/s
by sliverstorm on Tuesday April 16, 2013 @06:15PM
(#5561295)
Re: FPGAs, don't forget their other major downfall for mining- power. An equivalent ASIC uses much less power.
No. The Avalon ASIC only does a double-SHA256, and only attempts to brute force 4 of the 80 bytes in the input data. It cannot do any password cracking at all.
If you want it to, you would have to produce new wafers with a modified chip logic.
Re:1Password GPU brute-force with 3M hash/s
by pavel_lishin on Tuesday April 16, 2013 @05:57PM
(#5561203)
As I understand it, an ASIC is custom hardware to solve a custom problem - so it would probably be easier to build a custom one from scratch than convert a Bitcoin one. (Right?)
Right.
Probably only if the hash is a variant on SHA256, which is what the bitcoin protocol specifies. More complicated key derivation functions likely won't fit the limits of the hardware, and of course scrypt is expressly designed to defeat massively parallel application of digital logic (it scales with storage bandwidth instead).
No. In theory the FPGA boards could be repurposed, in practice no-one's bothered yet.
Re:1Password GPU brute-force with 3M hash/s
by alanctgardner2 on Tuesday April 16, 2013 @06:10PM
(#5561269)
Did a lot of miners buy pre-programmed FPGAs to do mining? If they're passe, they could probably recover a lot of the cost by selling them to students. Or donating them, since they're now rich (technically).