#user_controller.rb

class UserController < ApplicationController
  layout "index"

  def register

    @user = User.new(params[:user])

    if request.post?

      if @user.save
        flash[:notice] = "Thanks for registering."
        redirect_to :action => :register
      end
    end

  end

end

# register.rhtml

<h2>Register</h2>

<p>Please choose a user name and password.</p>

<%= start_form_tag :action => "register" %>

	<%= error_messages_for(:user) %>
	<% if @flash[:notice] %><div class="notice"><%= @flash[:notice] %></div><% end %>

	<label>Username:</label> <%= text_field "user", "username" %> <br />
	<label>Password:</label> <%= text_field "user", "password" %> <br />

	<%= submit_tag "Register" %>

<%= end_form_tag %>

# user.rb

require 'digest/sha2'
class User < ActiveRecord::Base
  def password=(pass)
    salt = [Array.new(6){rand(256).chr}.join].pack("m").chomp
    self.password_salt, self.password_hash =
      salt, Digest::SHA256.hexdigest(pass   salt)
  end
end