Learn Ethereum smart contract programming • Hacker News Board

Re: Learn Ethereum smart contract programming

#111

Post by mbrock » Mon, Jul 24, 2017, 1:23 PM UTC

mkagenius wrote: post #75

mbrock wrote: post #30

Earlier quoted context omitted.

You know Bitcoin is useful. One of the useful things in Bitcoin is that you can make a transaction conditional on a multiparty approval ("multisig"). This is used by many organizations to control funds in a safe way. Ethereum lets you construct even more interesting types of transactions. For example you can easily implement the logic of a crowdfunding (unless X is raised by time Y everyone is refunded). In that cont…

> In that context, "smart contract" is just a way of saying that you're not relying on the promise of a third party to perform the refund—it's automatic What if the code is malicious, and instead of auto refund it steals the money? I mean, not everyone would read the code to see what it really does, so what happens in that case?

There's no good solution for that problem yet. It's still in some sense better than centralized trust, because you can in principle understand the contract code. But we need to develop much better tools for auditing. Fortunately that's a really fun and interesting problem to work on!

Re: Learn Ethereum smart contract programming

#112

Post by throw2016 » Mon, Jul 24, 2017, 1:29 PM UTC

The problem with crypto coins is some have bought in and thus are vested making balanced discussion impossible. We see even with something as trivial as choice of programming language some can become very religious in their support. When money becomes involved expecting rational discussion is perhaps naive.

Money is a social construct that needs societal consent and a framework to manage it that is accountable to the societies rules and regulations. So a random person can't just create money or value out of thin air. There is no value being created here.

They can make a private coin, and convince others to use it between themselves, there were and still exist many such private arrangements in traditional economies, but the value only exists for those who choose to trust this system, and can never hope to replace the main economic currency.

Bitcoin and other coins exists in this space of a private coin based on mutual trust and of no real value to the main economy. Holders of such coins would of course love for it to become a real currency and continue making outlandishly self serving arguments about the economy so they can gain something out of nothing. But that begins to resemble a pyramid scheme powered exclusively by greed and self interest to the exclusion of that society's interests.

Re: Learn Ethereum smart contract programming

#113

Post by mbrock » Mon, Jul 24, 2017, 1:31 PM UTC

mannykannot wrote: post #93

maedha wrote: post #83

Earlier quoted context omitted.

> I mean, not everyone would read the code to see what it really does, so what happens in that case? This is true with real world contracts too, that's why people hire lawyers - they understand the "code" of contract law.

Except that in real-world contract and criminal law, there are various mechanisms that attempt, with some degree of success, to dissuade fraudulent behavior and allow for some form of restitution. Blockchain currencies, on the other hand, have been promoted partly on the premise that they are free of this sort of governmental interference.

Promoters gonna promote. Governments gonna govern.

Re: Learn Ethereum smart contract programming

#114

Post by DalasNoin » Mon, Jul 24, 2017, 1:37 PM UTC

kbody wrote: post #109

The sad reality of Ethereum: 1. Bitcoin is slow and expensive, Ethereum is the future 2. Ethereum software has security hole, gets hacked 3. Ethereum fans say it's an experiment there are lots of things that will transform Ethereum (Casper/PoS, Raiden, zkSNARKs, Enterprise Alliance) 4. Low price getting pumped by Ethereum Foundation & big-holder affiliates 5. Back to #1 We've seen it happen again (DAO) and again (Par…

"but the takeover-the-world echo-chambers of ethereum that don't focus at all on the real tech behind it and ignore everything negative is pretty disappointing" i dont think this is a good representation of the ethereum community, most people on r/ethereum for example are quiet self conscious about the security issues. that is at least my impression from reading the threads there.

Re: Learn Ethereum smart contract programming

#115

Post by Keeeeeeeks » Mon, Jul 24, 2017, 1:38 PM UTC

jesusthatsgreat wrote: post #86

staticelf wrote: post #17

The problem I see with Ethereum is that it is way too complex. I have read perhaps at least 10 times on their home page without even understanding what it does, what problems it solves etc. This is the sole reason why I don't think it will be successful in it's current state. With most successful tech or services or whatever the core idea is often super simple to grasp and you can instantly see the benefit. I don't s…

Maybe if you actually used it you'd see the benefits of it... try transferring any amount of value with Bitcoin.. take note of how much it costs and how long it takes. Then do the same with Ethereum. You'll start to learn pretty quickly what some of the main differences are. Regarding the 'fixed amount of Bitcoins' argument, I'd agree it's a nice simple marketing message but if you look in to what Ethereum is plannin…

At this point, people could convert from btc and use any random shitcoin for value transfer, then convert back to USD

Re: Learn Ethereum smart contract programming

#116

Post by naasking » Mon, Jul 24, 2017, 1:42 PM UTC

staticelf wrote: post #17

The problem I see with Ethereum is that it is way too complex. I have read perhaps at least 10 times on their home page without even understanding what it does, what problems it solves etc. This is the sole reason why I don't think it will be successful in it's current state. With most successful tech or services or whatever the core idea is often super simple to grasp and you can instantly see the benefit. I don't s…

> Smart contracts is probably the key word but I don't understand how it works or how it will benefit me.

I virtually guarantee you don't really understand how the regular monetary system works either, but you can still use it and have some idea of how it benefits you. Ethereum can be used to set up another monetary system whose currency flows are guarded by code-driven contracts that anyone can write.

So imagine the e-bay auction process as a smart contract that's controlled directly by the monetary framework, without involving Paypal or credit card companies, or any other centrally managed financial institutions.

The core idea behind Ethereum is sound and first envisioned a long time ago [1], but the current implementation leaves a lot to be desired. The Ethereum languages are being designed by programmers who try to address the needs one encounters in programming, like delegation patterns and some types of dynamism that makes extension and reuse easier.

Unfortunately, this is often the opposite of what you want for robust contracts, where writing the contract is not the important part, it's understanding all of the possible outcomes and what causes them. The dynamism makes static analysis hard, so understanding the behaviour of the complete system is too difficult, and vulnerabilities proving this point will continue to crop up.

[1] http://erights.org/smart-contracts/index.html

Re: Learn Ethereum smart contract programming

#117

Post by naasking » Mon, Jul 24, 2017, 1:47 PM UTC

runeks wrote: post #62

hexhex wrote: post #33

I didn't have high expectations for Solidity considering the recent vulnerabilities, but even these were disappointed. If some guy writes this kind of code at home, alright, but this as the alleged foundation for our future financial system? Frightening. Just one example: "Our function EndLottery() must be only accessible by the owner of the lottery." [0] function EndLottery() public { if (msg.sender == owner) { ...…

Many issues with Solidity as a contract language were pointed out in a previous HN thread after the Parity multisig-incident: https://news.ycombinator.com/item?id=14810008

I'll do you one better, vulnerabilities directly associated with the dynamism of Solidity were predicted on LtU in 2014:

http://lambda-the-ultimate.org/node/5003

Re: Learn Ethereum smart contract programming

#118

Post by nerdponx » Mon, Jul 24, 2017, 1:48 PM UTC

throwanem wrote: post #107

mannykannot wrote: post #100

Earlier quoted context omitted.

Unless the attacker is careless enough to reveal his identity, or puts his ill-gotten gains at risk of being hacked back, or the victims are Ethereum foundation members, your chances of restoration are slim to none.

So I'm actually at a disadvantage here, compared to plain old contracts.

Yes. If one party makes a mistake, or does something underhanded/surreptitious, you have no recourse. This exact situation (a bug in the DAO contract leading to a malicious actor stealing from the DAO) led to the recent Ethereum fork: https://news.ycombinator.com/item?id=14819268

Re: Learn Ethereum smart contract programming

#119

Post by mbrock » Mon, Jul 24, 2017, 1:49 PM UTC

kbody wrote: post #109

The sad reality of Ethereum: 1. Bitcoin is slow and expensive, Ethereum is the future 2. Ethereum software has security hole, gets hacked 3. Ethereum fans say it's an experiment there are lots of things that will transform Ethereum (Casper/PoS, Raiden, zkSNARKs, Enterprise Alliance) 4. Low price getting pumped by Ethereum Foundation & big-holder affiliates 5. Back to #1 We've seen it happen again (DAO) and again (Par…

The belief that Turing machines aren't amenable to formal verification is a hobgoblin that shows up in every thread like this, but it's not real.

Of course there are limited formalisms that make certain types of verification easier, but proving programs has been possible since, like, the 1960s.

A multisig, for example, has a finite number of states when considered under symbolic execution. A model checker can rip through it and prove whatever properties you want.

Is the Ethereum world right now full of buggy contracts that haven't been proven correct? Yes, absolutely. It's a disaster. But it's a disaster that points the way fairly straightforwardly.

Should Ethereum not have been launched until it had solid methods for auditing and proving? Maybe, but that's not how the world works, typically. Worse is better and all that.

Re: Learn Ethereum smart contract programming

#120

Post by teod » Mon, Jul 24, 2017, 1:52 PM UTC

k__ wrote: post #102

anilshanbhag wrote: post #101

Earlier quoted context omitted.

I would suggest you read the white paper ( https://github.com/ethereum/wiki/wiki/White-Paper ) The short answer is contracts are accounts. Just like your normal ethereum accounts. When you invoke a method marked as payment, you are essentially transferring some ether from your account to the contract. If someone wrote contract from which you can't withdraw and you send ether to it, thats stupidity - even fiat can be…

I see, thank you :) Stupidity? Doesn't Ethereum want to prevent all money getting locked up somewhere?

I believe there are times when it is favorable to "burn" ether or another cryptocurrency, i.e. lock up the money in an unowned account. For example, the decentralized market place OpenBazaar discusses proof-of-burn to establish a user's reputation (https://blog.openbazaar.org/proof-of-burn-and-reputation-ple...). Burning coins allows a user to show they are invested in their reputation on the platform, without being forced to pay money to a central party.