Questions tagged [addresses]

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

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115 votes
6 answers
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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?
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143 votes
6 answers
109k views

How are ethereum addresses generated?

What criteria does a valid Ethereum address need to fulfill? Is it just a random number in hexadecimal? Or does it need to be derived in a specific way, according to some cryptographic algorithms? ...
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59 votes
5 answers
42k 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)?
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44 votes
3 answers
72k 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 ...
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32 votes
2 answers
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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 ...
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34 votes
2 answers
16k 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 ...
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22 votes
3 answers
21k 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 ...
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16 votes
1 answer
3k 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') ...
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79 votes
9 answers
85k 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 ...
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  • 2,485
28 votes
4 answers
28k 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 ...
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  • 970
22 votes
3 answers
6k 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 ...
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17 votes
6 answers
17k views

How to convert an address to bytes in Solidity?

What is the recommended way to convert an address to bytes in Solidity?
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30 votes
5 answers
18k 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?
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49 votes
3 answers
28k 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 ...
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15 votes
3 answers
11k views

Ethereum Vanity Address generators

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 ...
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55 votes
4 answers
17k 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 ...
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70 votes
3 answers
67k 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 ...
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32 votes
5 answers
17k 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 ...
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  • 433
21 votes
2 answers
8k 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?
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  • 261
9 votes
3 answers
7k 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 ...
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  • 93
8 votes
1 answer
3k 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 ...
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27 votes
1 answer
9k 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) ...
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29 votes
5 answers
32k 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
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19 votes
4 answers
30k 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 ...
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14 votes
4 answers
9k 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 ...
19 votes
1 answer
7k 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 ...
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10 votes
1 answer
14k 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 { ... } ...
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11 votes
2 answers
9k 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....
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1 vote
2 answers
245 views

How (without libraries) can I get the public address from a private key?

I want to know a way to know the public address used for funds transfer from the private key. (As myetherwallet do when you get your wallet info by entering your private key) I don't care with wich ...
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  • 111
2 votes
1 answer
4k views

Why does the transaction exceed block gas limit? [closed]

When I try sending ether to another account, I keep getting the message "Exceeds block gas limit". I changed the gas amount from 5,000 to 100,000 but nothing else happened. Why does the transaction ...
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  • 1,858
14 votes
3 answers
71k 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 ...
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  • 141
8 votes
1 answer
8k 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?
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12 votes
2 answers
6k views

Is address(this) a valid address in a contract's constructor?

When does a smart contract's address first become valid? Is the address during the execution of the contract, or only after it's been fully instantiated and initialized? In other words, is a contract'...
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11 votes
1 answer
2k views

How to generate a vanity address for a smart contract to be deployed on?

I am aware of the possibility to generate vanity addresses for normal accounts. However, how is possible to generate vanity addresses for external owned accounts (which host smart contracts)? I'm ...
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6 votes
4 answers
3k views

Get address from public key in Solidity

The address is the last 20 bytes of sha3(publicKey) In Solidity, using assembly if needed, how could I splice the first 12 bytes from sha3(publicKey) and get the address? What I came up with runs out ...
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  • 159
13 votes
2 answers
13k 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 ...
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6 votes
2 answers
6k 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 ...
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  • 2,008
5 votes
3 answers
904 views

Relationship between Ethereum Address and public key

Understand ethereum Address is a hash of a public key. We still need to encrypt message with public key to be verified with private key. What is the use of the Ethereum address in the first place?
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3 votes
3 answers
13k views

Reinstalled MetaMask, account lost?

I had 3 accounts under my MetaMask Chrome extension. One of them had some small deposit. I have reinstalled the extension and used seed phrase to get access again. However, I can see only one account (...
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0 votes
3 answers
5k views

Unused function parameter. Remove or comment out the variable name to silence this warning

I have a smart contact which have 2 owner address and 3 functions. my set functions is set a users with msg.sender and my getUser functions is returns name,surname and age and I want to add a admin ...
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5 votes
4 answers
32k views

How to transfer Ether between accounts in Solidity?

I'd like get ether balance of account in solidity. I tried the following, but it didn't work. Could you tell me how to do it? contract MultiplyContract{ address public buyer; address public ...
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  • 2,237
5 votes
2 answers
1k views

Common Gas Wallet for ERC20 Wallets?

We have a wallet structure where users send tokens to individual user wallet addresses generated for them, we then sweep all the funds in the user's wallets to a centralized pool. The individual ...
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3 votes
2 answers
1k views

Receive payments in Ethereum ERC-20 tokens in web-services

I want to receive payments in my web-service in Ethereum tokens, for example, EOS or REP. And, of course, I must provide each user with different addresses for payment to determine who is the payer, ...
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  • 31
7 votes
1 answer
5k 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.
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  • 917
2 votes
1 answer
2k views

Are addresses between different networks (testnet) interchangeable?

I am designing user interface having both Ethereum mainnet and testnet addresses. Is it possible for the user to accidentally give testnet address when withdrawing in mainnet and vice versa? How can ...
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11 votes
1 answer
17k views

Solidity: How to specify a (hard-coded) address as a literal

I am defining a contract and I want to ensure a particular member variable can only be modified by me. So, specifically I want to ensure that if someone else deploys one of my contracts, then they ...
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  • 246
8 votes
3 answers
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 ...
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  • 31.4k
7 votes
2 answers
12k views

How to generate an Ethereum address using Web3.js using a string of text or brain wallet?

I want to implement a brain wallet like address generator using web3.js -- I basically have a string of text and want to convert this into an Ethereum address. How can this be done?
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5 votes
2 answers
4k views

Generating an address from a public key

Been learning about generating wallets in Ethereum and things have been smooth until the point where I turn a public key into an actual address. Multiple sources say to use Keccak to hash the public ...
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  • 178
3 votes
1 answer
6k views

Generate new address in Ethereum node using Json-RPC

Well, first of all, I am very new to Ethereum and maybe I am asking something stupid but my question is the following. I feel comfortable using json-rpc commands and I want to know how can I create a ...
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