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Ethereum is a next-generation cryptocurrency platform

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Re: Ethereum is a next-generation cryptocurrency platform

#51

Post by ogreyonder »

aaron-lebo wrote: post #46
ogreyonder wrote: post #44

Earlier quoted context omitted.

I'm interested in seeing a real explanation of the Dagger algorithm. In brief: the only source I can find (that page) just contains a few sloppy lines of pseudocode. Where is real description and proof of its properties? https://news.ycombinator.com/item?id=7115825

There's been further discussion of Dagger. http://www.reddit.com/r/ethereum/comments/1vh94e/dagger_upda... Not just in this link but in another that I cannot find, the devs seem to be leaning towards a bybrid PoW/PoS system like Peercoin. Edit: Quote was, "We will switch our PoW from Dagger to a hybrid PoW/PoS system to be developed via a bountied competition conducted by our university partners and open to the gener…

A hybrid system sounds reasonable, but I'm more interested in how they think that Dagger is ASIC-proof. I can't tell without a real description of the algorithm, but what is presented doesn't seem hard to parallelize.

Re: Ethereum is a next-generation cryptocurrency platform

#52

Post by oleganza »

nullc wrote: post #50
oleganza wrote: post #16

Earlier quoted context omitted.

OP understands better than many of us why and how Bitcoin works. Script execution is limited by the fee (which is paid upfront). If the contract is paid to take 10 ops and 2 slots, if it uses more than that or takes longer than 10 ops to execute, it will be aborted and money will forever be locked.

But these fees are only paid to miners— not all the other nodes validating the transactions. If only miners validate, what will keep miners honest (e.g. from writing themselves a blank check for more coins).

That's the same argument about non-mining Bitcoin nodes. Those who choose maximum security have to perform thousands of ECDSA checks and store the whole blockchain. For everyone else there's Masterc... mobile app. Your argument is valid, but not (imho) specific to Ethereum.

Re: Ethereum is a next-generation cryptocurrency platform

#53

Post by nullc »

oleganza wrote: post #52
nullc wrote: post #50

Earlier quoted context omitted.

But these fees are only paid to miners— not all the other nodes validating the transactions. If only miners validate, what will keep miners honest (e.g. from writing themselves a blank check for more coins).

That's the same argument about non-mining Bitcoin nodes. Those who choose maximum security have to perform thousands of ECDSA checks and store the whole blockchain. For everyone else there's Masterc... mobile app. Your argument is valid, but not (imho) specific to Ethereum.

The distinction for Bitcoin is that a smartphone can keep up with the maximum possible computation load from validation.

The design is very purposefully limited to keep the validation computation so cheap that it is effectively free, and no amount of fee paying can convince miners to allow more computation since the limits are a property of the system enforced by all nodes just as the supply of coin is limited.

I think it's a less useful mental model to think of what Bitcoin is doing as execution. What a Bitcoin script is really is a witness of an execution that the signer performed— proof that he executed it faithfully— rather than the computation itself. It's just a product of engineering that the simplest (to implement) way to verify execution is to perform it again, but its not intrinsic.

Re: Ethereum is a next-generation cryptocurrency platform

#55

Post by [deleted] »

JulianMorrison wrote: post #35
oleganza wrote: post #30

Earlier quoted context omitted.

Ether scripts are not operating in unrestricted environment. They are turing-complete, but their environment and available memory are very restricted. A bug in the implementation may lead to denial-of-service attacks (just like similar bugs in Bitcoin), but it does not mean there will be ether viruses spreading through the network. At worst, it could be a global DoS issue that can be quickly fixed and the entire hist…

I do not share your optimism. The worst case is autonomous viruses that steal to sustain their transaction fees and escape their jails to wreak havoc via buffer overruns or other similar exploits.

[deleted]

Re: Ethereum is a next-generation cryptocurrency platform

#56

Post by pulgrot »

nhaehnle wrote: post #45
sanxiyn wrote: post #27

Apart from scripting, they came up with a new proof-of-work function, which takes exponentially more memory to compute compared to checking. It is probably of independent interest. http://wiki.ethereum.org/index.php/Dagger

Looking at the very bottom of that page, I do not understand how that function would prevent ASIC mining from being significant. You still need to compute a huge number of (SHA-3) hashes, and speeding these up could still make a significant difference, couldn't it? I guess that in the limit, the speed-up is less relative to Bitcoin-style mining. Still, as long as modern CPUs are not memory-bound during computation of…

Increased memory usage is directly related to the silicon size. ASIC mining could be more efficient, but not orders of magnitude so like with bitcoin.

Re: Ethereum is a next-generation cryptocurrency platform

#57

Post by tromp »

ogreyonder wrote: post #43
sanxiyn wrote: post #28

Earlier quoted context omitted.

Ethereum is designed to be extremely hard to scale for mining. It does not use Bitcoin mining. Go read about it.

http://wiki.ethereum.org/index.php/Dagger#Algorithm_specific... : You sound knowledgeable, so perhaps you could clean up their algorithm for me? There are a number of problems with their description that make it hard for me to evaluate. Having tried designing a memory-hard algorithm, I'd like to see what their key insight was, but there are a number of problems with their article. They use confusing operators, the wr…

Cuckoo Cycle at https://github.com/tromp/cuckoo seems like a better proof-of-work system and comes with a full implementation.

It has the following features:

1) proofs take the form of a length 42 cycle in the Cuckoo graph, so that verification only requires computing 42 hashes.

2) the graph size (number of nodes) can scale from 1x2^10 to 7x2^29 with 4 bytes needed per node, so memory use scales from 4KB to 14GB. Use of 4GB+ should make it somewhat resistent to botnets.

3) running time is roughly linear in memory, at under 1min/GB for the current implementation on high end x86.

4) no time-memory trade-off (TMTO) is known, and memory access patterns are the worst possible, making the algorithm constrained by memory latency.

5) it has a natural notion of difficulty, namely the number of edges in the graph; above about 60% of size, a 42-cycle is almost guaranteed, but below 50% the probability starts to fall sharply.

6) the choice of cycle length allows a tradoff between benefit (algorithmic hardness) and cost (proof size), similar to the choice of the number of rounds in a cryptographic hash or encryption function.

Re: Ethereum is a next-generation cryptocurrency platform

#58

Post by ogreyonder »

tromp wrote: post #57
ogreyonder wrote: post #43

Earlier quoted context omitted.

http://wiki.ethereum.org/index.php/Dagger#Algorithm_specific... : You sound knowledgeable, so perhaps you could clean up their algorithm for me? There are a number of problems with their description that make it hard for me to evaluate. Having tried designing a memory-hard algorithm, I'd like to see what their key insight was, but there are a number of problems with their article. They use confusing operators, the wr…

Cuckoo Cycle at https://github.com/tromp/cuckoo seems like a better proof-of-work system and comes with a full implementation. It has the following features: 1) proofs take the form of a length 42 cycle in the Cuckoo graph, so that verification only requires computing 42 hashes. 2) the graph size (number of nodes) can scale from 1x2^10 to 7x2^29 with 4 bytes needed per node, so memory use scales from 4KB to 14GB. Use…

Thanks! This looks really cool, I'll check it out.

Re: Ethereum is a next-generation cryptocurrency platform

#59

Post by ChuckMcM »

mikeash wrote: post #25
adobriyan wrote: post #20

Earlier quoted context omitted.

Technical term is "Factory". :^)

Well, it depends on context. In Java, they're factories. The more general term seems to be "platform". For the world of cryptocurrencies, I'd propose "mint".

CryptoCurrencyFactoryFactory :-)

Re: Ethereum is a next-generation cryptocurrency platform

#60

Post by wmf »

oleganza wrote: post #14
ansible wrote: post #2

I like that it is mildly inflationary over the long term, as opposed to deflationary.

Just like Bitcoin: https://ip.bitcointalk.org/?u=http%3A%2F%2Fwww.mattwhitlock....

In this context, inflation and deflation are commonly understood to be the ratio between supply and demand of the currency. Assuming significant adoption and any economic growth, demand for BTC will increase faster than supply, hence deflation.
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