Bitcoin Wiki - User contributions [en]

Talk:Myths

2011-04-23T17:57:17Z

Shrewdwatson: /* Bitcoin mining is a waste of energy and harmful for ecology */ new section

= Terrorism =
From the linked Wikipedia page:
:The USA PATRIOT Act defines terrorism activities as "activities that (A) involve acts dangerous to human life that are a violation of the criminal laws of the U.S. or of any state, that (B) appear to be intended (i) to intimidate or coerce a civilian population, (ii) to influence the policy of a government by intimidation or coercion, or (iii) to affect the conduct of a government by mass destruction, assassination, or kidnapping, and (C) occur primarily within the territorial jurisdiction of the U.S."

This definition is broad enough that it could probably be applied to the Bitcoin system. IANAL but I imagine lawyers could pretty easily demonstrate that Bitcoin is 'dangerous to human life' because the Four Horsemen can use it for evil [drug-dealers, money-launderers, terrorists, and pedophiles.] It can 'influence the policy of a government by coercion' by removing options such as Federal Reserve dollars. (C) might be tricky to prove.
[[User:PLATO|PLATO]] 22:34, 23 March 2011 (GMT)

: besides the one attorney general that made a snide remark about terrorism in the LibertyDollar case, i don't think that this is in any way a 'common misconception', so i'd question whether we need to have the 'terrorism' section at all.--[[User:Nanotube|Nanotube]] 04:02, 24 March 2011 (GMT)

I agree. All yes for removing terrorist stuff? [[User:EvanR|EvanR]] 00:10, 30 March 2011 (GMT)

== Bitcoin mining is a waste of energy and harmful for ecology ==

IMHO this chapter is superficial. Compare Bitcoin to electronic fiat currencies. --[[User:Shrewdwatson|Shrewdwatson]] 17:57, 23 April 2011 (GMT)

Talk:Block

2011-04-23T13:49:21Z

Shrewdwatson:

== What if I'm 1% towards calculating a block and...? ==

"There's no such thing as being 1% towards solving a block. You don't make progress towards solving it."

Is this true? I don't know if there's a nonce which will solve any given block, but for a block that is solvable, it's possible to be 1% of the way towards finding it. Supposing it takes 10 million attempts to 'solve' a block, then after 100,000 attempts you could say you were 1% towards solving it. You're certainly closer to solving it than you were before those 100,000 failed attempts, aren't you? [[User:Dooglus|Dooglus]] 05:05, 15 January 2011 (GMT)
:No one can know how many tries it will take to solve the block. After the fact you might say that at some point you had finished 1% of the necessary calculation for that block, but this was not really "progress".

:If you go back in time after completing a block and don't generate for one of the days that you did originally, then you could actually end up getting the block ''sooner'', as the work required is random. [[User:Theymos|theymos]] 11:06, 15 January 2011 (GMT)

Probabilistically speaking, one can make a "best guess" for how long it will take to solve a block. A problem with probabilistic estimation, for example, is that it may say it will take 10 hours to solve the block, with a standard deviation of 15 hours. How much more work do you have when you've worked on it for 10 hours? The answer is that you have ~10 hours more work :).

But assuming all incorrect hashes are exhausted first, the maximal number of tries needed to solve the block is ~2<sup>256</sup>. So, there exists an upper limit (albeit, it is an obscenely large one!) on the amount of work you can do. Progress is made, just very slowly. --[[User:Dlo|Dlo]] 20:28, 11 April 2011 (GMT)
:That's not the maximum. You can't predict the hash outcome, so you could try forever and still get values above the target. You'd get repeat hash values from the same input. [[User:Theymos|theymos]] 03:47, 18 April 2011 (GMT)
::I can predict the hash outcome by calculating SHA-256 with my mighty x86 processor. :) IMO "predicting" is irrelevant here. Dlo is assuming that the hash function is injective, therefore the number of incomes (giving outcome above the target) <= 2^256. But the hash function is not injective (by the cardinality argument: the set of incomes is infinite and the set of outcomes is finite). --[[User:Shrewdwatson|Shrewdwatson]] 13:49, 23 April 2011 (GMT)

Talk:Block

2011-04-23T13:48:58Z

Shrewdwatson:

Talk:How bitcoin works

2011-04-23T11:41:50Z

Shrewdwatson: predict a cryptographic hash function

== predict a cryptographic hash function ==

"Both the chaining, and the difficulty, are achieved via the SHA256 cryptographic hash function. The hash function essentially takes a block of data, and transforms it, in an effectively-impossible to reverse or to predict way, into a large integer. Making the slightest change to a block of data changes its hash unpredictably"

IMO the words "predict", "unpredictably" is misleading. The SHA256 cryptographic hash function is deterministic, so its result can be predicted by... the same function. :)

The key property is that the reverse function is costly, that's all.