public async Task <User> Register(User user, string password)
        {
            byte[] passwordHash, passwordSalt;
            HashPassword(password, out passwordHash, out passwordSalt);

            user.PasswordHash = passwordHash;
            user.PasswordSalt = passwordSalt;

            await dataContext.Users.AddAsync(user);

            await dataContext.SaveChangesAsync();

            return(user);
        }