account.rb

require 'digest/sha1'

class Account
  include MongoMapper::Document
  attr_accessor :password

  # Keys
  key :name,             String
  key :surname,          String
  key :email,            String
  key :crypted_password, String
  key :salt,             String
  key :role,             String

  # Validations
  validates_presence_of     :email, :role
  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       :email,    :within => 3..100
  validates_uniqueness_of   :email,    :case_sensitive => false
  validates_format_of       :email,    :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i
  validates_format_of       :role,     :with => /[A-Za-z]/

  # Callbacks
  before_save :generate_password

  ##
  # This method is for authentication purpose
  #
  def self.authenticate(email, password)
    account = first(:email => email) if email.present?
    account && account.verify_password(password) ? account : nil
  end
  
   def verify_password(password)
     hash_password(password, self.salt) == self.crypted_password
  end


  private
    def generate_password
      return if password.blank?
      self.salt = Digest::SHA1.hexdigest("--#{Time.now.to_s}--#{email}--") if new_record?
      self.crypted_password = hash_password(password, self.salt)
    end

    def password_required
      crypted_password.blank? || !password.blank?
    end

    def hash_password(password, salt)
      Digest::SHA512.hexdigest("#{password}:#{salt}")
    end    

end