[Ethereum] Generate ethereum address in C#

addresseskeccak

I'm following the instructions here to generate a valid ethereum address from scratch. I'm using BouncyCastle's secp256k1 to do the privkey –> pubkey, but I don't know where to get a proper implementation of keccak for C# to do the final step pubkey –> address. Can anyone help me with this?

The BouncyCastle KeccakDigest does not return the same result as in the instructions for the same pubkey.

Best Answer

BouncyCastle KeccakDigest does seem to work : https://github.com/Nethereum/Nethereum/blob/master/src/Nethereum.Util/Sha3Keccack.cs

public byte[] CalculateHash(byte[] value)
        {
            var digest = new KeccakDigest(256);
            var output = new byte[digest.GetDigestSize()];
            digest.BlockUpdate(value, 0, value.Length);
            digest.DoFinal(output, 0);
            return output;
}

The complete process of generating an address can be understood by the code in https://github.com/Nethereum/Nethereum/blob/master/src/Nethereum.Signer/EthECKey.cs, especially

public string GetPublicAddress()
{
            var initaddr = new Sha3Keccack().CalculateHash(GetPubKeyNoPrefix());
            var addr = new byte[initaddr.Length - 12];
            Array.Copy(initaddr, 12, addr, 0, initaddr.Length - 12);
            return new AddressUtil().ConvertToChecksumAddress(addr.ToHex());
}

Related Solutions

[Ethereum] How does keccak256 concatenate values inside a Solidity smart contract

The arguments are expressed as bytes, left-padded with zeroes to the maximum length of the data type you've passed in, and concatenated without any kind of delimiter.

In Python, given two hex-encoded bytes32s prepended with a 0x called first and second, it looks something like:

# keccak, change before upgrading pysha >= 3.10
from sha3 import sha3_256 
from rlp.utils import decode_hex

my_hash = "0x" + sha3_256(
   decode_hex(first[2:].zfill(64)) + 
   decode_hex(second[2:].zfill(64))
).hexdigest()

The decode_hex there is turning hex into an array of bytes.

PS the modern versions of Solidity and pysha, and probably the relevant library in whatever language you're using, now have versions of keccak called keccak or keccak256, so it's probably better to standardize on those.

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

Enter your address in https://etherscan.io/ and copy the uppercase/lowercase checksummed version and paste it into your solidity code.

contract Sample {
  address constant public myAddress = 0xE0f5206BBD039e7b0592d8918820024e2a7437b9;
  uint public vari;
  function setVari(uint a) {
    if(msg.sender == myAddress) {
      vari = a;
    }
  }  
}

And the warning message will disappear. The compiler checks the checksummed address for validity.

But I just checked your code with the checksummed address in Remix and I get a new warning message:

Untitled4:4:39: Warning: Initial value for constant variable has to be compile-time constant. This will fail to compile with the next breaking version change.
  address constant public myAddress = 0xE0f5206BBD039e7b0592d8918820024e2a7437b9;
                                      ^----------------------------------------^

This second error will disappear if you remove the constant modifier.

Best Answer

Related Solutions

[Ethereum] How does keccak256 concatenate values inside a Solidity smart contract

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

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