Bitcoin and the double-spending problem (2013)

blogs.cornell.edu

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> With a powerful botnet engaged in bitcoin mining, this attack becomes more likely

Botnets are irrelevant to Bitcoin mining these days. The datacenters full of ASICs that miners are using now can easily outmine any botnet made of ordinary PCs or servers no matter how large.

I see this article is close to 2 years old. A lot has changed since then.

I agree. Mods/Op should add "(2013)" to the title to avoid confusion (but as others have pointed out, the article is not only old but wrong in important points).

>cracking a SHA256 hash function given to them dependent on the rate at which mining is currently being done. The only known method to accomplish this is to randomly test different prime number pairs in brute force fashion.

Bruteforcing a sha prefix has nothing to do with prime numbers. In the case of bitcoin mining, an arbitrary nonce is included in a block. Different values of this nonce are tested in order to get a resulting hash with the required number of leading zeros.

Yep, I stopped reading there.

The author here demonstrates not only lack of knowledge but lack of imagination, since with the ability to crack SHA (at mining speeds no less) would open up a world of craziness, like being able to mine yourself a Google.com certificate in under ten minutes.

The paper this refers to [1]. Not waiting for confirmation has nothing to do with double spend. Its a probabilistic measure - the original paper show the poisson distribution, based on number of confirms. Beware of noobs with algebra. "As we show in this work, the propagation of double-spending alerts in the network would constitute a first important step towards efficiently detecting doublespending." The bitcoin project is waiting for their pull-request.

[1] http://eprint.iacr.org/2012/248.pdf

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