Questions tagged [addresses]

Addresses are the particulars of names, domains or accounts on the blockchain.

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109
votes
4answers
72k views

How are ethereum addresses generated?

What criteria does a valid ethereum address need to fulfil? Is it just a random number in hexadecimal? Or does it need to be derived in a specific way, according to some cryptographic algorithm? What ...
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?
57
votes
8answers
41k views

How can I check if an Ethereum address is valid?

I've read many times that you should never input an address by hand unless you want to accidentally send Ether into no-mans-land. I'd like to know what those checksums might be. Is there a way to tell ...
51
votes
4answers
13k views

Why don't Ethereum addresses have checksums?

A checksum, similar to its use in Bitcoin addresses, can primarily prevent mistyped or invalid addresses from being used, before a transaction with an invalid address is constructed. Why don't ...
45
votes
3answers
69k views

How to backup mist wallets?

I know I can backup the keystore files from my running ethereum client which holds my accounts. But how can I backup wallets created with mist? Is it enough to write down the public address where the ...
38
votes
2answers
28k views

Is Ethereum wallet address case sensitive?

I sent some amount of ETH to a wallet. I checked the wallets balance on ether chain. I entered the address in the search field and noticed both lowercase and uppercase versions of the address seemed ...
35
votes
3answers
15k views

Get public key of any ethereum account

Can I somehow get the public key of an ethereum account knowing just the corresponding ethereum address (e.g. 0x54dbb737eac5007103e729e9ab7ce64a6850a310)?
27
votes
2answers
9k views

How to encrypt a message with the public-key of an Ethereum address

I am writing some code in nodejs/browser. I have successfully created ethereum-addresses with the secp256k1-library. I was also able to sign and verify messages. Now I want to encrypt/decrypt a ...
26
votes
1answer
8k views

Cannot perform write functions in smart contract - invalid address?

I have the following simple smart contract... contract SimpleStorage { uint storedData; function set(uint x) { storedData = x; } function get() constant returns (uint retVal) ...
25
votes
4answers
5k views

How to detect if an address is a contract?

I'm interested in knowing whether any particular address is a contract address or a standard address. There have been similar questions on the topic, but I'm not looking to detect whether an address ...
23
votes
3answers
16k views

Calling function from deployed contract

I want to know how to instantiate an existing contract deployed on the blockchain using its address. e.g: contract A { function f1() {} } A is deployed on the blockchain, and in contract B I ...
21
votes
2answers
4k views

Is each Ethereum address shared by (theoretically) 2 ** 96 private keys?

Summary This is an extended question to How are ethereum addresses generated?. In Ethereum, a private key is 256-bit long, but an address is only 160-bit long. By "Pigeonhole Principle", it ...
19
votes
3answers
4k views

Account uniqueness guaranteed?

When we create an account in the Ethereum main network, how does the protocol guarantee the unique address of an account? Since even if we are not connected to the network we can create an account, is ...
19
votes
3answers
17k views

How to list transactions from account address?

I have a small service where people can exchange cryptocurrencies. Every user has its own Bitcoin, Litecoin, etc address for balance deposit. Now I want to add Ethereum. So I thought I will create ...
18
votes
3answers
3k views

How does a contract find out if another address is a contract?

Is it possible, from within a contract written in Solidity, to check if a contract is placed on a specific address or if this address does not contain any code?
16
votes
4answers
11k views

Convert address to string

In Solidity, how can I convert the sender address to a string? The comments in How to convert an address to bytes in Solidity? did not provide a working solution
16
votes
4answers
5k views

How do Ethereum clients generate unique addresses?

How do Ethereum clients, like Ethereum Wallet or Eth-Lightwallet, generate unique addresses that haven't been used before, and what is the likelihood that these addresses have been used?
16
votes
1answer
4k views

How Can I Add My Name Next To Address On Etherscan?

I'm wanting to set up a charity and want to use a public wallet for accepting donations with on Etherscan where I can have a displayed name next to the wallet like this: How Can I Add My Name Next To ...
16
votes
2answers
4k views

Is it safe to reuse Ether addresses?

I believe it's viewed as unsafe in Bitcoin because of the way transactions are signed. Is this also true for Ether addresses?
15
votes
1answer
2k views

Getting the wrong address back from ecrecover

When I sign a string using the following code I get back a different address to the one I signed with. The address returned is different for different strings. const util = require('ethereumjs-util') ...
14
votes
4answers
10k views

Can solidity contract arrays receive arrays of addresses as parameters?

This question is related to this one but using address arrays instead of strings. Does solidity support arrays of addresses to be passed as method arguments? contract C { uint256 hexVal = 0xABCD; ...
13
votes
3answers
3k views

Multiple transactions from same address

I would like to create multiple transaction from the same address at the same time. Since every transaction needs nonce (tx count of the sender address) I can ask geth for the current count and create ...
13
votes
3answers
53k views

How to create an Ethereum address?

I know basically zero about Ethereum, block chain etc. I have Augur reps. I have been asked to create an Ethereum address for the sale augur site. I don't have the slightest idea how to generate an ...
13
votes
4answers
8k views

What Hierarchical Deterministic (HD) wallets are available for Ethereum?

A Hierarchical Deterministic (HD) wallet has some nice features such as easier backup (instead of needing to backup multiple keystore files and the passwords for each of them). Are there any ...
12
votes
4answers
16k views

Ethereum Address vs Public Key

I'm creating an ethereum wallet and I'm a bit confused with the concept of public key vs address. I understand that the Address is a hashed version of the public key, but when I'm generating a new ...
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 ...
12
votes
1answer
6k views

Is an Account in MetaMask the same as an Ethereum Account (EOA)?

First, my setup: I use the Azure Ethereum Consortium Template, which creates one transaction node and two mining nodes in my configuration. I use MetaMask Chrome plugin to accept transactions, which I ...
11
votes
2answers
3k views

What's the difference between 'address' and 'address payable'?

I saw a Solidity smart contract where some variables were declared with the type address and some were declared with the type address payable. What are the differences between the two? Do they store ...
11
votes
2answers
5k views

Are there other Vanity Address generators available?

Are there any Ethereum vanity address generators available other than: Vanityreum (python) Vanieth (go) Which is the fastest? Can they be optimized further? What is the use-case of vanity ...
11
votes
1answer
2k views

Can an Ethereum address hold more than Ether?

Let me explain it with examples. On Bitcoin protocol, for example, you have Counterparty. As it uses embedded consensus, every XCP address is linked to a Bitcoin address. So if you hold bitcoins on ...
10
votes
5answers
7k views

How to convert an address to bytes in Solidity?

What is the recommended way to convert an address to bytes in Solidity?
10
votes
2answers
1k views

Programmatically saving the contract address of a submitted contract

I understand how the below web3js code block works, adapted from here: https://github.com/ethereum/wiki/wiki/JavaScript-API#web3ethcontract But how does one save the contract address ...
10
votes
2answers
6k views

How to list all the contracts currently on the blockchain?

I know one way to interact with contracts is, in the geth interface, to use the command: eth.contract(ABI).at(Address) But for this I will need to know the ABI and address of the contract in advance....
8
votes
3answers
6k views

Convert an eth key to a geth key

I need to convert my eth key to a geth key. eth put the key in %appdata%\roaming\Web3\keys, and I see it as a .json file. If I move that to the %appdata%\roaming\Ethereum\keystore directory, geth ...
8
votes
1answer
3k views

Return Token Contract address on truffle deploy

I am trying to figure out how to return the address of a contract when I deploy it with truffle's deployer.deploy. So the goal is that when I deploy a contract that is a custom token, I want to ...
8
votes
1answer
1k views

Why are Ethereum addresses hashes of public keys?

I understand how Ethereum addresses are generated. This thread has a great explanation: How are ethereum addresses generated? However, what this explanation is missing is why a hash is used. There ...
8
votes
1answer
537 views

How could msg.sender != tx.origin AND extcodesize(caller) == 0 be true?

I'm working on a puzzle where msg.sender != tx.origin, so the implication is that the caller needs to be a contract or at least something in between the calling account. But extcodesize(caller) == 0 ...
8
votes
2answers
1k views

Some characters in Ether addresses have changed to capitals after upgrading Mist

I recently upgraded Mist from 0.3.9 to 0.5.0. I have noticed that the capitalisation of some of the characters in my public address have changed. Is this normal?
8
votes
3answers
1k views

What is the Global Registrar?

Some guy on reddit found an address with 235 ETH in his wallet. He was confused about how he managed to get so much ETH. Commentators told him that it is the global registrar object. Here is an ...
7
votes
1answer
8k views

What's a fallback function when using address.send(…)?

This code is in my contract: contract A { address x = 0x1234...; x.send(10); } What would fallback function in the contract at address 0x1234... look like? contract B { ... } ...
7
votes
1answer
3k views

How to get address from private key in java

I use generate a private key in java code HashUtil.sha3("cow".getBytes()) Write to a new private key file: c85ef7d79691fe79573b1a7064c19c1a9819ebdbd1faaab1a8ec92344438aaf4 Then, I use geth account ...
7
votes
1answer
2k views

What is an ICAP address?

It appears ethereum is using plain hexadecimal addresses like 0x0092e965928626f8880629cec353d3fd7ca5974f for now. I noticed, the ethereum C++ implementation outputs so called ICAP addresses, check ...
7
votes
2answers
860 views

What is the ENS-BurnAddress?

I stumbled upon this Ethereum address. Etherscan calls it the ENS-BurnAddress. Currently, the account holds more than $9,000,000 US. My guess is that this is used to impose a cost on each bid so ...
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.
7
votes
1answer
2k views

Should I create a new address for each transaction?

It's my understanding, when using bitcoin, it's advisable to generate a new address for every transaction. Is this also the case for Ethereum, and if so, how do I do this with Mist?
6
votes
3answers
8k views

How to check for valid contract address using web3?

I am simply trying to avoid the error: Error: invalid address web3 throws this error when the address to a contract is not valid. Is there a way to catch this error ? I am using web3 in a nodejs ...
6
votes
2answers
5k views

Are funds returned if one transfers from an exchange to an invalid Ethereum address?

I transferred some ether form an exchange site to an invalid address (invalid in that the correct address was trailed by 6 numbers I accidentally pasted in). Looking for that address on Ethereum ...
6
votes
3answers
3k views

Why are there no change addresses?

What's the concept behind ethereum transactions that allows them not to require change addresses? What's the underlying difference compared to - for example - bitcoin?
6
votes
2answers
2k views

Find address which called the method?

How can a contract method find the address which invoked it? Suppose I have a contract A with method B. I used xyz address to call method B then how can method B see xyz address.
6
votes
3answers
3k views

Why does mist throw 'Uncaught invalid address'?

I'm trying to make a web page that gets a message from a simple "hello world" smart contract. Unfortunately, it isn't working. I'm seeing this in the Mist console. Uncaught invalid address v ...