How to create a asp.net membership provider hashed password manually?

Question

I'm using a website as a frontend and all users are authenticated with the standard ASP.NET Membership-Provider. Passwords are saved "hashed" within a SQL-Database.

Now I want to write a desktop-client with administrative functions. Among other things there should be a method to reset a users password. I can access the database with the saved membership-data, but how can I manually create the password-salt and -hash? Using the System.Web.Membership Namespace seems to be inappropriate so I need to know how to create the salt and hash of the new password manually.

Experts step up! :)

Answer 1

I used reflector to take a look at those methods the .NET-Framework is using internal. Maybe there are public methods available for this but I did not find them - if you know how to query those internal methods as a user please left a comment! :)

Here is the simplified source-code without unnecessary conditions because I only want to encode the password as a SHA1-Hash:

private string GenerateSalt() {
  var buf = new byte[16];
  (new RNGCryptoServiceProvider()).GetBytes(buf);
  return Convert.ToBase64String(buf);
}

private string EncodePassword(string pass, string salt) {
    byte[] bytes = Encoding.Unicode.GetBytes(pass);
    byte[] src = Convert.FromBase64String(salt);
    byte[] dst = new byte[src.Length + bytes.Length];
    byte[] inArray = null;
    Buffer.BlockCopy(src, 0, dst, 0, src.Length);
    Buffer.BlockCopy(bytes, 0, dst, src.Length, bytes.Length);
    HashAlgorithm algorithm = HashAlgorithm.Create("SHA1");
    inArray = algorithm.ComputeHash(dst);
    return Convert.ToBase64String(inArray);
}