Ethereum address genеration and keccаk256

Question

I'm trying to generate eth address on PHP. Having issue with keccak256.

I'm using this class: https://github.com/kornrunner/php-keccak

It works good, I checked many times on https://emn178.github.io/online-tools/keccak_256.html

Priv/pub keys are generated right, checked many times, but there is something with keccak256, and I get different address from myetherwallet and other tools.

Where is a mistake?

Here is my code:

include('./keccak.php');
use BitWasp\BitcoinLib\BitcoinLib;
require_once(__DIR__. '/vendor/autoload.php');
$priv = '17d08f5fe8c77af811caa0c9a187e668ce3b74a99acc3f6d976f075fa8e0be55';
echo 'priv key: '.$priv;
echo "\r\n";
$pub=substr(BitcoinLib::private_key_to_public_key($priv),2); // deleting '04' padding from left side
echo 'pub key: '.$pub;
echo "\r\n";
$adr = \nmsps\Keccak::hash($pub, 256);
echo 'keccak256: '.$adr;
echo "\r\n";
echo 'ETH address:'.substr($adr,-40); // last 40
exit;

output:

priv key: 17d08f5fe8c77af811caa0c9a187e668ce3b74a99acc3f6d976f075fa8e0be55

pub key: 689268c0ff57a20cd299fa60d3fb374862aff565b20b5f1767906a99e6e09f3ff04ca2b2a5cd22f62941db103c0356df1a8ed20ce322cab2483db67685afd124

keccak256: c39d3fed9ca154a48cad5238a063d2fa1937d32fec5166ce0a27c6e6f94c95c8

ETH address: a063d2fa1937d32fec5166ce0a27c6e6f94c95c8 // should be 0x26d1eC50B4e62c1d1a40D16E7cacc6A6580757d5

Answer 1

The correct Keccak256 Hash for your public key should be

de77577a693274e6d5e229c326d1ec50b4e62c1d1a40d16e7cacc6a6580757d5

The reason it being c39d3fed9ca154a48cad5238a063d2fa1937d32fec5166ce0a27c6e6f94c95c8 is because the public key is treated as a string, instead of a byte array.

To illustrate this, it's best to compare the results between treating '689268c0ff57a20cd299fa60d3fb374862aff565b20b5f1767906a99e6e09f3ff04ca2b2a5cd22f62941db103c0356df1a8ed20ce322cab2483db67685afd124' as

• a string
• a byte array

I am not sure how to feed a byte array into the website in the question. So I am using python3 instead.

As string

python3
from Crypto.Hash import keccak
keccak_hash = keccak.new(digest_bits=256)
s='689268c0ff57a20cd299fa60d3fb374862aff565b20b5f1767906a99e6e09f3ff04ca2b2a5cd22f62941db103c0356df1a8ed20ce322cab2483db67685afd124
pub=bytearray()
pub.extend(map(ord, s))
keccak_hash.update(bytes(pub))
print(keccak_hash.hexdigest())

The output is

c39d3fed9ca154a48cad5238a063d2fa1937d32fec5166ce0a27c6e6f94c95c8

which matches your result

As byte array

python3
from Crypto.Hash import keccak
keccak_hash = keccak.new(digest_bits=256)
pub=bytearray.fromhex('689268c0ff57a20cd299fa60d3fb374862aff565b20b5f1767906a99e6e09f3ff04ca2b2a5cd22f62941db103c0356df1a8ed20ce322cab2483db67685afd124')
keccak_hash.update(bytes(pub))
print(keccak_hash.hexdigest())

This outputs

de77577a693274e6d5e229c326d1ec50b4e62c1d1a40d16e7cacc6a6580757d5

Verifying the 'As byte array' output

To verify the hash, we calculate the Ethereum address from this output.

echo de77577a693274e6d5e229c326d1ec50b4e62c1d1a40d16e7cacc6a6580757d5 | cut -c 25-

This outputs 26d1ec50b4e62c1d1a40d16e7cacc6a6580757d5

Now we import the private key using geth, which will print out the address according to its own calculation

cd $(mktemp -d)
echo 17d08f5fe8c77af811caa0c9a187e668ce3b74a99acc3f6d976f075fa8e0be55 > key.txt
geth --datadir . account import key.txt

Geth will ask for setting a password. Afterwards, it should output

Address: {26d1ec50b4e62c1d1a40d16e7cacc6a6580757d5}

which matches our calculation, thus proving the 'As byte array' approach is correct.