Quote from: MikesMechanix on June 29, 2011, 02:17:14 PM

Quote from: BubbleBoy on June 29, 2011, 12:39:18 PM

A single 5970 can try 10.000 keys per second of the 100.000 iteration variety, so it can break a 40 bit entropy password in about 100 days. If you can rent a 5970 for a few $/day, than you can break many wallets for a few hundred dollars each. You know from the start what wallet is worth cracking from those you managed to stole, since the public key thus the amount enclosed are stored in plain text. It would be cost effective to crack allinvain's wallet even if he uses a 50bit entropy password, which let's face it not many users do.

How did you come to these numbers?

@40 bits of entropy the average time to crack a password, given 10000 trials per second, is
2^40/10000/60/60/24/2 = 636 days

And, FWIW, a 8 character all-lowercase random alphanumeric is typically more than 40 bits entropy.

@50 bits
2^50/10000/60/60/24/2 = 651562 days

Hard to see the cost effectiveness of a 1000 5970s blasting out keys for a year or two. And that's still only an 8 character alphanumeric with one special character.

The 10k passwords/sec seems is a bit off. I've seen that on a few different forums. I think that was for cracking zip files or something.

A single 5870 can do 4.2 MD5 ghash/sec in whitepixel. A 5970 probably like 7 (in an x4 rig, they got 28.6 Ghash/sec).

At 40 bits that would be:

2^40/7000000000/60/2 = 1.3 minutes on average.

At 50 bits:

2^50/7000000000/60/60/2 = 22.3 hours on average.

Okay that can't be right. Would somebody please tell me what I'm assuming that is wrong? (Whitepixel data)