## user excerpt

require 'digest/sha1'

class User < ActiveRecord::Base

  # Virtual attribute for the unencrypted password
  attr_accessor :password

  validates_presence_of     :firstname, :lastname
  validates_presence_of     :login, :email
  validates_presence_of     :password,                   :if => :password_required?
  validates_presence_of     :password_confirmation,      :if => :password_required?
  validates_length_of       :password, :within => 4..40, :if => :password_required?
  validates_confirmation_of :password,                   :if => :password_required?
  validates_length_of       :login,    :within => 2..40
  validates_length_of       :email,    :within => 3..100
  validates_uniqueness_of   :login, :email, :case_sensitive => false
  validates_email_format_of :email
  validates_presence_of     :locale
  before_save :encrypt_password
  before_create :make_activation_code

   attr_accessible :title, :firstname, :lastname, :login, :email, :password, :password_confirmation, :locale

  # Activates the user in the database.
  def activate
    @activated = true
    self.activated_at = Time.now.utc
    self.activation_code = nil
    save(false)
  end

  # Locks this user by setting its deleted-attribute to the current time.
  def lock
    self.deleted = Time.now
    save(false)
  end

  # Unlocks this user.
  def unlock
    self.deleted = nil
    save(false)
  end

  # Checks if this user has been activated yet.
  def active?
    # the existence of an activation code means they have not activated yet
    activation_code.nil?
  end

  # Authenticates a user by their login name and unencrypted password.  Returns the user or nil.
  def self.authenticate(login, password)
    u = find :first, :conditions => ['login = ? and activated_at IS NOT NULL and deleted IS NULL', login] # need to get the salt
    u && u.authenticated?(password) ? u : nil
  end

  # Encrypts some data with the salt.
  def self.encrypt(password, salt)
    Digest::SHA1.hexdigest("--#{salt}--#{password}--")
  end

  # Encrypts the password with the user salt
  def encrypt(password)
    self.class.encrypt(password, salt)
  end

  # Checks if the given password matches either the normal password or the
  # temporary password and returns true, otherwise false.
  def authenticated?(password)
    epw = encrypt(password)
    case epw
      when temp_crypted_password
        self.crypted_password = temp_crypted_password
        self.temp_crypted_password = nil
        save(false)
        true
      when crypted_password
        unless temp_crypted_password.nil?
          self.temp_crypted_password = nil
          save(false)
        end
        true
      else
        false
    end
  end

  # Generates a password with eight characters from the current time, the user's
  # login and some random values.
  def gen_temp_password
    temp_password = random_password
    self.temp_crypted_password = encrypt(temp_password)
    save(false)
    temp_password
  end

  def random_password
    Digest::SHA1.hexdigest("--#{Time.now.to_s}--#{rand.to_s}--#{login}--")[0...8]
  end
....
end

## controller


  # Renders newpw.html.erb
  def newpw
  end

  # Generates a temporary password and sends it to the user's email-address.
  def createnewpw
    @user = User.find_by_login(params[:login])

    if @user
      temp_password = @user.gen_temp_password
      UserMailer.deliver_temp_password(@user, temp_password)
      flash[:notice] = 'A new password was mailed to your mail address.'.t
    else
      flash[:notice] = 'No such user!'.t
    end
    redirect_to(login_url)
  end