.NET provides various cryptographic methods to securely encrypt passwords. For .htpasswd files, the BCrypt algorithm is often recommended. This example uses the BCrypt.Net-Next library for password hashing.

First, ensure you have installed the BCrypt.Net-Next NuGet package:

Install-Package BCrypt.Net-Next
            

Use the following C# script to create a new .htpasswd file with a username and a hashed password:

using System.IO;
using BCrypt.Net;

var username = "myUsername"; // Replace with your username
var password = "myPassword"; // Replace with your password

var hashedPassword = BCrypt.Net.BCrypt.HashPassword(password);
var htpasswdContent = $"{username}:{hashedPassword}";

File.WriteAllText(".htpasswd", htpasswdContent);
            

To add a new user to an existing .htpasswd file, append the username and hashed password to the file:

using System.IO;
using BCrypt.Net;

var username = "newUser"; // Replace with the new username
var password = "newPassword"; // Replace with the new password

var hashedPassword = BCrypt.Net.BCrypt.HashPassword(password);
var htpasswdContent = $"\n{username}:{hashedPassword}";

File.AppendAllText(".htpasswd", htpasswdContent);