ruby on rails simple auth

rails_simple_auth_model.rb

# == Schema Information
#
# Table name: admins
#
#  id                 :integer          not null, primary key
#  username           :string(255)      not null
#  encrypted_password :string(255)      not null
#  salt               :string(255)      not null
#  created_at         :datetime
#  updated_at         :datetime
#

require 'digest/sha1'

class Admin < ActiveRecord::Base

  validates :username, :presence => true, :uniqueness => true, :length => { :in => 3..20 }
  validates_presence_of :encrypted_password, :on => :create
  validates_presence_of :salt, :on => :create

  def self.create_one(username, password)
    salt = Digest::SHA1.hexdigest("# We add #{username} as unique value and #{Time.now} as random value.")
    encrypted_password= Digest::SHA1.hexdigest("Adding #{salt} to #{password}")
    self.create(username: username, encrypted_password: encrypted_password, salt: salt)
  end

  def self.auth(username, password)
    admin = Admin.find_by(username: username)
    encrypted = Digest::SHA1.hexdigest("Adding #{admin.salt} to #{password}")
    if admin.encrypted_password == encrypted
      return admin.id
    end
end