simple mongoid auth

user.rb

require 'digest/sha1'

class User
  include Mongoid::Document

  attr_accessor :password, :password_confirmation

  field :email, type: String
  field :hashed_password, type: String
  field :salt, type: String

  before_validation :set_hashed_password

  def has_password?(pass)
    hashed_password == encrypt_password(pass, salt)
  end

  private

    def set_hashed_password
      self.salt ||= generate_salt
      self.hashed_password = encrypt_password(password, salt)
    end
    
    def generate_salt
      random_string = (0..25).map{ ('a'..'z').to_a[rand(26)] }.join
      Digest::SHA1.hexdigest(random_string)
    end
    
    def encrypt_password(password, salt)
      Digest::SHA1.hexdigest(password + salt)
    end

  class << self
    def authenticate(email, password)
      user = User.where(email: email).first
      return false unless user
      user.has_password?(password)
    end
  end
end


###################

u = User.create(email: 'test@example.com', password: 'password', password_confirmation: 'password')
=> #<User _id: 540ca2fe4d61722071000000, email: "test@example.com", hashed_password: "14f763e4ea4ba2bc38c6ba3f7c60de99a978dcd5", salt: "acf19b17ec24f70e5f4818b8899db480cba539b1">
u.has_password?('password')
=> true
User.authenticate('test@example.com','password')
=> true