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Bitcoin is "Worse is Better"

gwern.net

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Re: Bitcoin is "Worse is Better"

#31

Post by stygianguest »

gwern wrote: post #5
stygianguest wrote: post #3

Worse is better does not apply to bitcoin as a cryptographic system, only as a monetary system. As a cryptographic system it makes a clear choice for more features over simplicity. Make no mistake, bitcoin is a very complicated system. Not for a piece of software, but for a cryptographic system. One that aims to replace the fundaments of our economic system. With such ambition, "it seems to work," is not good enough.…

> As someone who has spend some time hacking the bitcoin code, I would say I have little confidence. There are a lot of differing opinions on this. I quoted Kaminsky at length as someone with major security credentials who is saying the opposite of you.

Sorry, missed that. Very interesting and indeed, his opinion easily trumps mine. However, I would like to see some evidence rather than the word of an expect (if only to learn). For example he says that "This code has the mark of having been audited by People Like Us", what marks would that be?

Re: Bitcoin is "Worse is Better"

#32

Post by gwern »

asdfaoeu wrote: post #30
gwern wrote: post #26

Earlier quoted context omitted.

I'm afraid you're going to have to be explicit, because the idea of using Bcrypt for that reason makes perfect sense to me - the logic that makes Bcrypt better than SHA-256 for passwords seems to apply nicely to Bitcoin. Hardware optimization privileges the few who can invest in the hardware over the many who are able to run more commodity hardware, and is exactly contrary to the P2P Bitcoin ethos. (A similar point a…

Bcrypt isn't specifically harder to compute on GPUs. It just has an adjustable amount of work it has to do which increases the load. Bitcoin effectively has the same thing with the difficulty.

...Not really. The point is not that you can make it harder, as you say both Bcrypt and zero-finding in SHA hashes can be adjusted and made harder. The point is that the constant factor speedups available from specialty hardware are greater for SHA than they are for Bcrypt.

Re: Bitcoin is "Worse is Better"

#33

Post by wnight »

tptacek wrote: post #21
browep wrote: post #17

Earlier quoted context omitted.

i'm not really worried about the intrinsic value of bitcoin, it goes up, it goes down, it doesn't matter. You don't have to store your wealth in bitcoin, USD goes in USD goes out when you want it to at usually 0.5% transaction cost ( or less some places ). And there's no reason Flitcoin can't succeed in the same places. I'm not sure why that would have anything to do with intrinsic value or why intrinsic value is of…

In other words, you're content to ride out the "greater fool" theory, confident that you'll be able to jump out before the market spirals down to zero. And that's fine, but it doesn't address the question that roots this thread.

In other words, you're ignoring all problems about value transfer systems like gold and cash while assigning basic problems like that nobody trades food for gold when starving to BTC alone.

Gold for instance, seems to be a fool's buy, because there are few truly-useful non-technical things to do with it (you can't eat it) but actually works well as a basis for some value transfers. In a crash your bitcoins would depreciate wildly because nobody would part with anything of value for some bits - or a piece of paper - or some shiny metal.

This is just inherent in trading - there has to be a difference in value or the trade wouldn't happen, and if there's a difference in value the values may not relatively correspond at all points.

To some people, at some times, a token may be a useful marker in trade, as cash is now. With World of Warcraft healthy, there can be a good market in magic swords. With a healthy world economy, cash can be useful. When either fails, current holders will suffer. Gold will suffer differently, it won't be counterfeit or lost, but it won't be liquid. Ditto for BTC, they just become irrelevant relative to food.

Gold is anonymous, but can't practically be traded that way in large quantities. Cash is only pseudonymous like BTC as usually used - bills are scanned when dispensed and deposited. It's not globally visible, just to the most likely and well funded enemy - your own government.

It really seems like you should be harshing on representational value systems in general, or something.

Re: Bitcoin is "Worse is Better"

#34

Post by tptacek »

gwern wrote: post #32
asdfaoeu wrote: post #30

Earlier quoted context omitted.

Bcrypt isn't specifically harder to compute on GPUs. It just has an adjustable amount of work it has to do which increases the load. Bitcoin effectively has the same thing with the difficulty.

...Not really. The point is not that you can make it harder, as you say both Bcrypt and zero-finding in SHA hashes can be adjusted and made harder. The point is that the constant factor speedups available from specialty hardware are greater for SHA than they are for Bcrypt.

First, I don't think your specific point is true. Second, and more importantly, the benefit of hardware isn't that it changes the constant factors; it's that it parallelizes the search. The whole point of scrypt is to create a state explosion that prevents that parallelization.

Re: Bitcoin is "Worse is Better"

#35

Post by tptacek »

stygianguest wrote: post #31
gwern wrote: post #5

Earlier quoted context omitted.

> As someone who has spend some time hacking the bitcoin code, I would say I have little confidence. There are a lot of differing opinions on this. I quoted Kaminsky at length as someone with major security credentials who is saying the opposite of you.

Sorry, missed that. Very interesting and indeed, his opinion easily trumps mine. However, I would like to see some evidence rather than the word of an expect (if only to learn). For example he says that "This code has the mark of having been audited by People Like Us", what marks would that be?

I have no idea what he means by that.

Re: Bitcoin is "Worse is Better"

#36

Post by gwern »

tptacek wrote: post #34
gwern wrote: post #32

Earlier quoted context omitted.

...Not really. The point is not that you can make it harder, as you say both Bcrypt and zero-finding in SHA hashes can be adjusted and made harder. The point is that the constant factor speedups available from specialty hardware are greater for SHA than they are for Bcrypt.

First, I don't think your specific point is true. Second, and more importantly, the benefit of hardware isn't that it changes the constant factors; it's that it parallelizes the search. The whole point of scrypt is to create a state explosion that prevents that parallelization.

Parallelization is a constant factor. If you have 1000 processors, you get a constant-factor one-time speedup of 1000x (or less). No complexity class changes.
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