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5
votes
1answer
377 views

How can we conserve disk space or compress the blockchain?

The blockchain is eating into my macs disk space. Will there be a way in the future to compress it or redirect to an external hard drive?
24
votes
3answers
7k views

Which database(s) do the ethereum clients use and why?

Ethereum clients (such as geth, eth, pyethapp, ethereumj, and ethereumH) download the Ethereum blockchain from their peers and then store a copy of it locally, presumably indexed within some sort of ...
13
votes
2answers
766 views

What is the way to make Ethereum available to users for free?

As the web is mostly free today (I mean the old web, the one < 3), most people won't agree in beeing asked for fuel to run sites, apps, even if the gain in terms of safety and trust are so much ...
46
votes
1answer
46k views

Which TCP and UDP ports are required to run an Ethereum client?

The geth CLI options suggest that per default the client listens on TCP port 30303. This page, additionally suggests that UDP port 30301 is used for node discovery. Is this all that is required or ...
4
votes
1answer
829 views

Who are the main developers of Ethereum?

Bitcoin has a handful of core developers like Gavin, Mike Hern, and etc that are the gatekeepers to implementing core features depending on community feedback. Who are the core devs in Ethereum and ...
4
votes
3answers
602 views

Can a smart contract code be used to generate a bitcoin public/private key pair address?

Seeing that a smart contract is just code. How would it be possible to make a smart contract generate a Bitcoin public/private key pair and send it to a user without anyone knowing the pair.
6
votes
1answer
614 views

Can you do a POST to an external webform using a Ethereum smart contract?

Can you do POST or submit a form from an external site using a smart contract? And how can this be done? Are there any examples of live code out there?
6
votes
3answers
1k views

Can you copy or fork someone else's smart contract? Is it open source code?

Is it possible to just copy someone else's smart contract? Say if someone has a profitable smart contract, what stops someone from just copying it to get a piece of the profit pie?
11
votes
2answers
513 views

Can I send gas to another user?

Gas is purchased using Ether, does that mean I can send gas as a separate coin?
5
votes
2answers
418 views

Which competing technologies are similar to Ethereum?

Ethereum is widely known for its smart contract system, but which other competing technologies are also out there that does something similar. Just like in the early days of Bitcoin, many clone coins ...
16
votes
1answer
6k views

How much does it cost to use a contract?

Still new to ethereum and would like to know the price for a contract.
1
vote
0answers
2k views

As of Feb 2016, how big is the ethereum blockchain size and its monthly growth rate? [duplicate]

As of Feb 2016, how big is the ethereum blockchain size and its monthly growth rate? Does the blockchain implement anything with pruning to reduce its size in the near future?
3
votes
1answer
322 views

Example of embedding arbitrary data / text into a contract to be sent to another account?

Since users can create smart contracts, can't someone just embed plain text into the smart contract and then have that sent to another user in effect making it a messaging system? and how much would ...
4
votes
3answers
3k views

Which trustworthy sites can I generate a brain wallet for ethereum?

I'm looking to generate a brain wallet for ethereum. Which sites are trustworthy to do this without my coins being stolen?
4
votes
1answer
409 views

Live demo of parsing data from external API's like twitter into an Ethereum smart contract

I'm looking to make a simple ethereum smart contract to just monitor a twitter weather feed for the word "sunny". And if its sunny, it would send coins to some account I specify. Are there any live ...
21
votes
2answers
2k views

What are best practices for serving a DApp over HTTPS, connecting to an Ethereum node using JSON RPC / web3.js, which by default uses HTTP?

Summary: we're serving an Ethereum DApp from a webserver through HTTPS. The DApp connects to an Ethereum node through JSON RPC using web3.js, which uses HTTP (not HTTPS). How to deal with this in a ...
2
votes
1answer
752 views

How to use contracts deployed by embark on the server side of a meteor app?

I have created my example using embark meteor_demo and then changed my configuration on embark.yml to output the contract on the server folder instead of the client. From that point i started getting ...
9
votes
1answer
298 views

What is the utilisation level on the Ethereum blockchain? [duplicate]

How many transactions are currently executed on the Ethereum blockchain and how does this compare to other blockchains?
3
votes
1answer
257 views

Is it possible to launch the C++ eth client without unlocking the accounts?

Each time I run eth it requests my master password. I don't feel comforatble with permanently running a node with unlocked accounts. Is it possible to launch the C++ eth (or alethzero) client without ...
4
votes
1answer
254 views

Is it possible to check which RPC APIs are available?

Is it possible for a decentralized application to get details about the offered JSON-RPC APIs from the local ethereum node? I want to check the following specs in the following order using web3.js: ...
20
votes
4answers
11k views

Does Web3.js have the functionality to create new accounts and unlock an account for a period of time for a series of transactions?

I want to create new accounts through my Dapp web interface and unlock a specific account so that transactions can be processed. I didn't see it in the web3.js documentation so wonder if that's on the ...
7
votes
2answers
1k views

web3.sha3 dealing with hex in both geth and web3.js

in both geth and web3.js, when we call > web3.sha3("0x536f6d6520415343494920737472696e6720746f20626520686173686564") we get: requirement of using web3.fromAscii before sha3 is deprecated new ...
11
votes
2answers
648 views

I bought ether in the presale. Is there a time limit to claim that ether?

There is no mention in the documentation about whether I have to claim ether before a particular date. Is there a time-limit on claiming ether? I've also heard that the mining algorithm will change at ...
143
votes
2answers
27k views

What is the difference between a transaction and a call?

What is the difference between a transaction and a call? In some interfaces, I can interact with contracts via calls or via transactions. What is the difference between the two, and can contracts also ...
31
votes
2answers
4k views

Do contracts also have a nonce?

Do contracts also have a nonce and if so how is it calculated? Usual accounts have a nonce that is increased with every transaction. However, contracts can't make transactions, they can only make ...
5
votes
1answer
388 views

Do Ethereum and Bitshares have similar concepts or technology?

In the Bitshares official website they're explaining the functionality of the tool and in general look like Ethereum. What makes Ethereum different of Bitshares?
75
votes
5answers
23k views

How is the address of an Ethereum contract computed?

How is the address of an Ethereum contract computed? What use cases are there for knowing a contract's address in advance?
1
vote
0answers
139 views

How to sign anything with my ethereum private key and verify with public key? [duplicate]

How can I use the private key of my eth.accounts[0] to sign a file from outside Ethereum, so people can verify that the file belongs to that account with the public key?
13
votes
2answers
1k views

If someone gets my geth keystore files, can they spend my ETH without knowing my password(s)?

I always assumed so, since geth requires a new password for every account, but just want to be sure.
8
votes
2answers
4k views

Getting more Ether on a private test net

I setup a local testnet using geth following these instructions. I was able to mine my initial Ether and all was working. After deploying some contracts I quickly spent all the Ether I had. Now it ...
12
votes
3answers
1k views

How to build an AST for Solidity?

I'm trying to build a parser for Solidity, and it would help if I could build a working version off of the existing parser. I've tried looking at the source code on the official git, but I haven't ...
-1
votes
1answer
325 views

What capacity is ethereum using recently?

What capacity is ethereum using recently? How many more people can use ethereum now? What is current blocksize, and what are all the data being broadcasted between nodes? I read that ethereum just ...
4
votes
1answer
262 views

What is the web3 filter.watch() scope?

If I create a nested filter.watch filter_a.watch( filter_b.watch(); ); If I call filter_a.stopWatching(); does filter_b.watch() go out of scope for web3.js? Does geth keeps sending filter_b....
7
votes
2answers
3k views

How to manipulate data in a Solidity smart contract?

I have a smart contract with some members which should get modified on certain events. For simplicity, let's imagine we have a greeter contract. If I call greeter.greet() in the JavaScript console, ...
9
votes
2answers
333 views

Why do I get serialization errors in calling events?

I have put some events in my contracts like this event TokenTransfer(address indexed sender,address indexed receiver,uint32 indexed num_tokens); event ExceptionEvent(uint16 indexed retcode,address ...
2
votes
2answers
2k views

Attaching an address for a contract to call another contract

I am writing code where I want to call other contracts within my current contract. Bank.sol contract Bank { address owner; mapping (address => uint) balances; function init() ...
34
votes
5answers
21k views

How to concatenate strings in solidity?

I'm trying to concatenate two strings in solidity. I tried with + or . but neither option works. There is not much documentation on string concatenation yet. Is it even possible? If not, can I ...
3
votes
1answer
244 views

What is an 'uDApp'?

The online solidity compiler offers an output of smart contracts labelled uDApp, for example the greeter uDApp looks like that: [{"name":"greeter","interface":"[{\"constant\":false,\"inputs\":[],\"...
5
votes
4answers
1k views

How to design a legal smart contract?

In Ethereum the terms "Contract" or "Smart Contract" are loosly used; "Smart Agent" might have been a better name [citation-needed]. Most smart contracts are certainly not legal contracts. Now for a ...
2
votes
1answer
898 views

Is it possible to *write* (not print) a paper wallet without having to copy a big JSON?

In Bitcoin, you can store a paper wallet by merely writing down the private key of an address, which is very small. You can also write ~20 words generated from that address, if you want. In Ethereum, ...
4
votes
2answers
671 views

Why isn't my contract getting a msg.sender? (solc 0.2.0-1)

TL;DR: Second's msg.sender isn't being set when it should. Consider these two contracts: First.sol: import "Second.sol"; contract First { address public second; function First() { } ...
12
votes
2answers
2k views

What's the difference between developer mode and testnet?

I just tried running geth in developer mode on testnet. ~ $ geth --dev --testnet F0127 21:07:16.947591 6407 flags.go:467] dev and testnet are mutually exclusive I wasn't aware of the actual ...
3
votes
1answer
2k views

How to connect mist to a testnet client?

I'm running a geth instance on the consensys testnet. I started it with the following command: geth --testnet --networkid=2 --bootnodes=enode://...
13
votes
1answer
138 views

Are there any barriers to implementing an ethereum node as a chrome or firefox extension?

Is it possible to create a Firefox or Chrome extension which ran either a full node or light node?
23
votes
1answer
8k views

How can I verify a cryptographic signature that was produced by an Ethereum address key pair

If I have a cryptographic signature from an Ethereum address key pair, how can I verify that signature?
20
votes
5answers
26k views

How do you stop a running geth node?

I can not figure out how to stop a running geth node without killing the process. I tried to lookup geth help but there is no mention of stopping, halting or any shutdown command. How to shutdown ...
3
votes
1answer
449 views

'symbol lookup error: /usr/lib/libdevcrypto.so' when running eth or mix?

I am getting the following error when running eth or mix: symbol lookup error: /usr/lib/libdevcrypto.so: undefined symbol: ...
3
votes
1answer
319 views

How to integrate Ethereum support into CoinSpace?

CoinSpace is a fork of the Hive Bitcoin Wallet and is in active development at github. I'm am interested in adding Ethereum to the wallet in the same way Litecoin is supported. I'm looking for any ...
29
votes
7answers
21k views

What are the differences between Bitcoin blockchain and Ethereum blockchain?

Ethereum has been debated in the bitcoin ecosystem and was criticized. In order to understand better both projects, what are the main differences between BTC and ETH regarding the blockchain ...
23
votes
1answer
2k views

How does the solidity optimizer work?

The compiler for solidity supports the flag --optimize which performs some set of optimizations to the compiled solidity code, typically resulting in a reduction of gas costs. How does the optimizer ...

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