Retrive Public key from a Bitcoin Private Key

Question

How i can get Bitcoin Address from a Bitcoin Private Key .

I understand the whole method except the first one where , the public key and its x and y cord comes from the hash/private key .

If i can get a code example in php it would be more helpful for me .

Answer 1

Well for starters use the following library:

https://github.com/RobKohr/PHP-Bitcoin-Address-Creator

optionally you could use a backend of vanitygen and generate addresses via exec(), shell_exec(), or even better escapeshellarg(). other than these two methods, your options would be to setup an rpc with a bitcoind server.

of course there are more complex solutions, such as what is located here(coinbit.tk, a splitkey vanity address generator that generates the private key in javascript)

https://github.com/RobKohr/PHP-Bitcoin-Address-Creator

if you still have trouble, see the following topic(s).

https://bitcoin.stackexchange.com/questions/2289/php-script-to-create-private-key-public-address

https://bitcointalk.org/index.php?topic=81626.0

Answer 2

Here's a NodeJS script to go from WIF -> Private Key -> Public Key -> Binary Address -> Human Readable Address

// EXAMPLE: node wif_details.js 5JuHN27YsJktraQYGgLeihxZ2bwQbFANFdpc8gtDgqyyJsZJQB6

const ecc = require('eosjs-ecc');
const base58 = require('bs58');
const ripemd160 = require('ripemd160')

const wif = process.argv[2];
console.log("WIF: ", wif);

const privkey = ecc.PrivateKey.fromString(wif);
console.log("Private Key: ", privkey.toBuffer().toString('hex'));

const compressed_pubkey = privkey.toPublic();
const uncompressed_pubkey = compressed_pubkey.toUncompressed();
console.log("Public key (compressed): ", compressed_pubkey.toHex());
console.log("Public key: ", uncompressed_pubkey.toHex());

const hash1 = ecc.sha256(compressed_pubkey.toBuffer());
const hash2 = new ripemd160().update(Buffer.from(hash1, 'hex')).digest('hex');
const hash3 = ecc.sha256(uncompressed_pubkey.toBuffer());
const hash4 = new ripemd160().update(Buffer.from(hash3, 'hex')).digest('hex');
const with_prefix_compressed = '00' + hash2;
const with_prefix_uncompressed = '00' + hash4;

const hash5 = ecc.sha256(Buffer.from(with_prefix_compressed, 'hex'));
const hash6 = ecc.sha256(Buffer.from(hash5, 'hex'));
const hash7 = ecc.sha256(Buffer.from(with_prefix_uncompressed, 'hex'));
const hash8 = ecc.sha256(Buffer.from(hash7, 'hex'));
const binary_address_compressed = with_prefix_compressed + hash6.slice(0,8);
const binary_address_uncompressed = with_prefix_uncompressed + hash8.slice(0,8);
console.log("Binary address (compressed): ", binary_address_compressed);
console.log("Binary address: ", binary_address_uncompressed);

const bitcoin_address_compressed = base58.encode(Buffer.from(binary_address_compressed, 'hex'));
const bitcoin_address_uncompressed = base58.encode(Buffer.from(binary_address_uncompressed, 'hex'));
console.log("Bitcoin address (compressed): ", bitcoin_address_compressed);
console.log("Bitcoin address: ", bitcoin_address_uncompressed);

Answer 3

This is not really what you are looking for, since you start from a specific private key. But if you just want to generate a private and public key, you might want to look into vanitygen, which generates both.