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12
votes
1answer
5k views

How to write my first Solidity “Hello World” smart contract?

I have never written a smart contract before because there is a lot attached to it getting it working. But I finally want to learn it now. I want to write a simple mininmal working smart contract ...
22
votes
1answer
2k views

What would be needed to store the blockchain as a IPFS object?

In Christian Lundkvists blog post about possible uses for IPFS, he suggests that storing the Ethereum blockchain as an IPFS object could potentially decrease the size of the chain: We see the ...
2
votes
1answer
470 views

What's involved in making a private chain become a sidechain of Ethereum?

"A private Ethereum-based network that had a linkage allowing ether to be securely moved from the public Ethereum main chain onto it and back would be considered to be a sidechain of the public ...
2
votes
1answer
54 views

What are common pitfalls when coding in Serpent?

Some pitfalls for coding in Solidity are here and what kind of pitfalls are there in Serpent? (This is not related to Python, which is covered here)
20
votes
2answers
6k views

Why aren't Solidity sha3 hashes not matching what other sha3 libraries produce?

Solidity has a function named sha3 and I tested it with an empty string input. It is not matching what other sha3 libraries produce. I see contracts written by others using the same sha3 function ...
9
votes
1answer
433 views

Are there any plans to switch Ethereum's primary hash algorithm from Keccak-256 to SHA3?

The Ethereum project was started before the SHA3 standard was finalised, and currently uses an earlier version of Keccak-256 which does not precisely match the FIPS-202 standard for SHA. Are there ...
2
votes
6answers
6k views

Are there any blockchain/transaction APIs for the Ethereum network?

In the Bitcoin world there are a number of APIs such as: blockchain.info blockr.io blockcypher.com etc. which allow a web application to access block and transaction data from the blockchain, as ...
17
votes
1answer
1k views

How does Casper solve the “Nothing at Stake” issue?

One of the criticisms of proof of stake is that stakers can vote for multiple blockchain forks with only a trivial cost. I believe NXT solves this by not giving out a mining reward, so that the ...
9
votes
1answer
707 views

How to avoid/detect multiple internal transaction out-of-gas side effects?

Following an issue I opened in github, this bothers me. The operation described in the issue, which happened during following avsa's tutorial on creating a DAO, generated two internals transactions as ...
88
votes
2answers
50k views

Which cryptographic hash function does Ethereum use?

Many sources refer to the use of the "SHA3" cryptographic hash function within Ethereum, but the Ethereum project began before the SHA3 standard was finalised, and there was some confusion/controversy ...
7
votes
1answer
778 views

How does Ethereum avoid mining pool centralization?

As a proof-of-work (PoW) based blockchain, how does Ethereum combat mining pool centralization, which can lead to an entity controlling the majority of hashing power?
8
votes
1answer
7k views

Security measures to overcome 51% attack

I was reading During a 51% attack, What Can the Attacker Actually Accomplish? from there, i understand the after-effects are something serious, so what are the security measures which ethereum have ...
16
votes
2answers
2k views

During a 51% attack, What Can the Attacker Actually Accomplish?

During an attack on the network, where the attacker has more than 51% of hashing power (or the equivalent of Ether in PoS), what can the attacker do and not do to the chain and the contracts on it? ...
4
votes
1answer
268 views

Security of PoS if/when Assets (Tracked or Native) to Ethereum exceed the total Value of Ether

Given that Ethereum naturally allows for the creation of arbitrary tokens that can either have value themselves or track a real-world asset, can Ethereum be secured by PoW/PoS when the total assets on ...
21
votes
2answers
1k views

What type of operations have negative gas costs?

I understand that some operations cost negative gas because they free up space on the blockchain, such as selfdestructs. What are all the operations that can have negative gas? Does this only occur ...
7
votes
1answer
4k views

JavaScript Code Required to Generate an Ethereum Address?

I am aware of several tools and websites that generate addresses for you, but I'm looking for an actual JavaScript code snippet to demonstrate the steps plainly.
11
votes
2answers
5k views

Do I need to encrypt the keystore file(s)?

When I run cat on one of the files in the keystore directory I see things like id, mac, etc. but I do not see private key. Is it safe to send the keystore file unencrypted over the internet? If the ...
9
votes
1answer
3k views

How to send ether to a cold storage account?

Is it possible to do the following: Back up the keystore on a usb drive. Format the computer used to generate the keystore. Send ether to a public address in the keystore. Reinstall geth (or other ...
21
votes
1answer
3k views

This image claims you can build “decentralized apps”, and each computer “contributes a little to process it”. Is that claim correct?

This image claims that you can put decentralized apps (say, a messaging program) on the Ethereum network. It also claims that each computer on the network contributes a little bit to the processing of ...
15
votes
1answer
4k views

What does it mean to “run code on the blockchain”? Wouldn't blockchain become huge?

More technically speaking, what does it mean to "run code on the blockchain"? Does it mean that we store the source code and then every full node runs that source code several times? If, for ...
24
votes
3answers
8k views

Are there any public/free nodes to connect a Dapp front end?

I have a small Dapp written in Meteor (client only) that reads some contract and account info from the blockchain. I can deploy my front-end code for free on meteor.com (or a variety of other places),...
8
votes
1answer
431 views

How hard is it for Ethereum clients to get on the new fork in case of an attack?

Vitalik Buterin writes: Assuming ~20% participation in PoS and current prices, you could stall or break the network at a cost of ~$7 million. However, unlike PoW, recovery is simpler: Ethereum just ...
21
votes
2answers
23k views

Why is geth always returning a 0 balance?

I installed geth on a remote server (Ubuntu 14.04) and created an account. I transferred 0.01 eth to the account. From my local machine (OS X), I can view the transaction and account balance ...
3
votes
2answers
274 views

Should we patent Dapps with new technology or processes?

I understand in the decentralized space patenting anything is generally frowned upon. Having said that, doesn't this expose Dapp developers to patent trolls, such as the Bank of America, from ...
12
votes
2answers
8k views

Should I always put 0x at the start of Ethereum addresses?

Should I always put 0x at the start of Ethereum addresses? Sending ether to addresses without 0x seem to work perfectly fine. when sending to an address, do you include the "0x" before the rest of ...
5
votes
1answer
3k views

What is the 0x I see around Ethereum? For example I see addresses that start with 0x

I see a number of things in Ethereum start with 0x, for example addresses. Other examples are in the Geth console, JSON-RPC, web3.js. What is the 0x and what is its purpose?
1
vote
1answer
61 views

From a technical perspective, is MultiSigna a decentralized exchange utilizing ethereum?

Does anyone know how we would be able to either view the Ethereum blockchain or inspect the code from Multisigna to confirm if it is a true ethereum decentralized exchange? Source: https://www....
5
votes
2answers
350 views

How do I add my Dapp to https://www.stateofthedapps.com/?

If I create a Dapp or start development on an Ethereum Dapp, what's the easiest way to get my Dapp listed on https://www.stateofthedapps.com/?
14
votes
3answers
3k views

What are State Channels and use case/code examples?

A previous Reddit post gave some indication: It's basically Lightning-network style payment channels but for arbitrary state updates. Participants in the Dapp send messages with transactions to ...
5
votes
1answer
216 views

How do remote nodes fit into a Dapp architecture?

The eth-lightwallet describes "remote nodes" in its implementation. This allows you to have full control over your private keys while still connecting to a remote node to relay signed ...
5
votes
2answers
1k views

What are the roles of ETHDEV, ETHCORE and the Ethereum Foundation?

I am trying to understand the institutional setup of Ethereum. I could identify the following institutions: (1) The Ethereum foundation, (2) ETHDEV and (3) ETHCORE. The foundation (1) is apparently ...
56
votes
6answers
189k views

How to import a plain private key into geth or Mist?

This is such a basic question, but I can not figure out how to import a plain, unencrypted private key into geth or mist? I tried geth account import 7[......]bla but it seems this command is always ...
4
votes
1answer
989 views

Deploying Meteor Dapps

What are currently the best architectural and deployment options for building and deploying a Dapp built with Meteor/Web3? For building the Dapp, a few Meteor packages are currently available : "...
8
votes
3answers
1k views

Ethereum conferences?

This is a similar question like the Statistics Conferences question at CrossValidated What are the most significant annual Ethereum conferences? Rules: Include a link to the conference Please ...
16
votes
5answers
3k views

What is a blockchain? What is the concept behind it? [closed]

I have been going through some docs, and I understand that BlockChains are mostly like the building blocks in an Ethereum network. So, can someone give a dumbed down explanation/definition about what ...
7
votes
5answers
2k views

Can I use Ethereum on my mobile phone?

What are the options to use Ethereum on my mobile (Android) smartphone? Is there a "mist for mobile"?
48
votes
4answers
11k views

Is there anything stopping me from using the ethereum blockchain as data storage?

As I understand it, smart contracts are currently immortal by default. Does this mean that I could create a contract that happened to contain an encoded form of baby photos and have it stored forever? ...
79
votes
6answers
159k views

What is the total supply of Ether?

In Bitcoin, the total supply is capped at 21 million BTC. Is the total supply of Ether capped? How much will be mined before the Proof of Stake (POS) transition, and how will POS affect the issuance ...
13
votes
4answers
616 views

What is the Identity function and what are its uses?

The contract at address 0x04 is the identity function. What is it and what are use cases for it?
35
votes
2answers
3k views

What's a precompiled contract and how are they different from native opcodes?

The Yellow Paper states: These are four so-called ‘precompiled’ contracts, meant as a preliminary piece of architecture that may later become native extensions. The four contracts in addresses ...
25
votes
3answers
85k views

What is the current DAG size? When do we expect to hit GPU limits?

I have two mining rigs running, one with 2GB GPUs and one with 8GB cards. Recently, the rig with the 2GB cards failed due to the inability to upload the DAG to the GPU. What's the current DAG size ...
6
votes
2answers
1k views

What does “resistance” mean in the context of a cryptocurrency exchange?

I was reading Where can I buy Ether? and they mention "least resistance" as a criterion for an exchange: Where are the best places to buy ether with the least resistance and lowest fees? What does ...
8
votes
3answers
7k views

What are digital tokens? How are various tokens generated on Ethereum?

I've heard in various talks, Ethereum can generate any token (besides ether), representing anything from bitcoin (through btc-relay), litecoin, dogecoin, digital assets, shares, ownership ...
25
votes
1answer
4k views

When can BLOCKHASH be safely used for a random number? When would it be unsafe?

I've seen more complicated ways for a contract to generate a random number. But the Ethereum Yellow Paper itself suggests a "trivial solution" using the BLOCKHASH opcode (see below, bold is mine). ...
10
votes
1answer
726 views

Why are contracts limited to only the previous 256 block hashes?

Why are contracts limited to only the previous 256 block hashes using the BLOCKHASH opcode (and corresponding functions in Solidity and Serpent)? Why does another contract, such as this, need to be ...
9
votes
1answer
1k views

What are the critiques of Ethereum made by Bitcoin experts? And which ones do not apply to Bitcoin?

Ethereum has been discussed by Bitcoin experts, for example on IRC such as #bitcoin-wizards. What are the critiques of Ethereum made by Bitcoin experts? Which ones apply and do not apply to Bitcoin?
7
votes
1answer
262 views

Ethereum walk-through

Would the following story line be a fair approximation of how Ethereum would work in this simplistic scenario? Simple network with just three nodes: N1, N2 and N3 N1 writes a contract that initiates ...
25
votes
3answers
6k views

Can a contract safely rely on block.timestamp?

How safe is it to use block.timestamp as contract expiration time? If a miner provides an incorrect timestamp in a block header, how much can it be off before it is rejected by other nodes? Is there a ...
10
votes
4answers
3k views

How can I configure Mist to use a non-default IPC path?

When using Mist, it always uses the default IPC path to my OS (In this case of OSX this is /Users/me/Library/Ethereum/geth.ipc). Is there a way to configure or specify a non-default IPC path for Mist? ...
13
votes
6answers
5k views

Is there any public Ethereum communication forums or Slack?

A lot of open source and blockchain projects are using Slack for communication and keeping communities together. Is there any public slack for Ethereum specifically (not DApps)?

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