15 questions linked to/from What is a replay attack?
How does the Ethereum ETH accounting system work and prevent double-spends?
In Bitcoin, the BTC accounting system is based on UTXOs (Unspent Transaction Outputs), which prevents the same BTC from being spent multiple times. I heard that Ethereum has a simpler account balance ...
How to prevent a replay attack between two competing chains?
After the recent hardfork we have a winning chain and a much shorter losing chain left. However, if you are pro or agains the fork, you could still mine and use one chain or the other. Now, there is ...
I've sent ether from testnet to mainnet but didn't receive anything. Why?
A few days ago I made a transaction at an address known to me (tx made from testnet to global main net). The transaction took place and received over 6 confirmations. The next day this transaction was ...
How to withdraw from live.ether.camp?
So last week I went on live.ether.camp and clicked the "Get Address" button then entered a seed phrase which I saved and still know. Then it told me my address was ready. I then bought 78 ethers on ...
What is the difference between account nonce and block nonce?
Block and accounts both use a value called "nonce" but they seem to represent something very different. For account I understand that the nonce is an integer quantity indicating the number of ...
Transaction receipts, blocks and confirmations
In Bitcoin, there is a best practice to wait between three to six block confirmations before accepting an transaction. This is to avoid double spending. Are there similar rules of thumb in Ethereum? ...
EIP155. How chainId works?
I know signed transaction got v=37. now I am wondering how 'v=37' is used to check that the transaction is right one. nodes check v of every transaction they received?
Post the DAO-fork, is there a double-spending problem?
If an account had ETH before the DAO-fork does the ETH now not exist on both the ETH and the ETC chains? A Poloniex notice says "All users who had an Ethereum balance at the moment of the fork now ...
Ethereum Hard Fork: what happened to legacy Ether?
I currently run Forked Ethereum via Parity. I'm assuming my Ether from before the fork is available on this chain. However, does it also still exist on the Ethereum Classic chain? I tried researching ...
Blockchain sync lost after restarting geth?
I'm new to mining ethereum so this may be a very basic question. I ran geth in attempt to sync the blockchain on my machine as follows geth --rpc --fast --cache=2048 After letting it spin for about ...
“txHash: undefined” error using web3.js
Can anyone help me fix this problem? I get 'txHash: undefined' error in terminal var Tx = require('ethereumjs-tx').Transaction const Web3 = require('web3') const web3 = new Web3('https://ropsten....
What various components are needed to trigger an Ethereum contract?
From what I understand, you must provide Ether so there's an incentive for miners to run the contract, but what else is provided? Must you sign cryptographically (to make sure an unrelated party ...
How does Ethereum know that I have enough ETH to spend?
Ethereum uses account-based model. It means that if account A has 50 ETH and sends 10 ETH to account B, transaction will look like "send 10 ETH from A to B" (no inputs and outputs as in UTXO). With ...
Is it bad security to use the same private keys and/or keyfiles across production, testnet, and dev?
I'd like to understand the security implications of re-using keys across a privatenet, the public testnet, and the production network. If this is bad, why so? Are there advantages or disadvantages to ...
Ethereum Mist wallet 0.8.0 won't receive any payments anymore
Mist would not receive any payments. I have not updated after 0.8.0. Is the reason because I have not done anything to choose which chain I will use?