I recommend you to look on Denovo. Coding Enthusiast must have probably implement it, it ain't difficult.
The following method contains all the subsequent methods that are called in order to create a private key from an integer of at most bitLen bits, convert to public key and finally get the corresponding address. You can find all those methods in Bitcoin.Net and see what they do. It goes without saying that a key created this way is a weak key.
Code:
public static void CreateWeakAddress(int bitLen, out string comp, out string uncomp)
{
if (bitLen > 256 || bitLen < 1)
throw new ArgumentOutOfRangeException();
// Create a random integer of at most bitLen bits
BigInteger mod = BigInteger.One << bitLen;
byte[] data = new byte[32];
using SharpRandom rng = new();
rng.GetBytes(data);
BigInteger value = new BigInteger(data, true, true) % mod;
// Convert to a private key (will check if in range and could throw ArgumentOutOfRangeException)
using PrivateKey key = new(value);
// Get pubkey and addresses
PublicKey pub = key.ToPublicKey();
comp = Address.GetP2pkh(pub, true);
uncomp = Address.GetP2pkh(pub, false);
// Other address types are possible too
_ = Address.GetP2wpkh(pub, true);
_ = Address.GetP2wpkh(pub, false);
_ = Address.GetP2sh_P2wpkh(pub, true);
_ = Address.GetP2sh_P2wpkh(pub, false);
}
