From bcf4e4f2b02157cecc1f1727a95cdf5bfa471771 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Sat, 18 Dec 2010 13:38:05 -0800
Subject: Added ActiveRecord::Base#has_secure_password (via
 ActiveModel::SecurePassword) to encapsulate dead-simple password usage with
 SHA2 encryption and salting

---
 activemodel/lib/active_model.rb                 |  1 +
 activemodel/lib/active_model/secure_password.rb | 73 +++++++++++++++++++++++++
 2 files changed, 74 insertions(+)
 create mode 100644 activemodel/lib/active_model/secure_password.rb

(limited to 'activemodel/lib')

diff --git a/activemodel/lib/active_model.rb b/activemodel/lib/active_model.rb
index be0f24ff92..dd6ee058cc 100644
--- a/activemodel/lib/active_model.rb
+++ b/activemodel/lib/active_model.rb
@@ -42,6 +42,7 @@ module ActiveModel
   autoload :Naming
   autoload :Observer, 'active_model/observing'
   autoload :Observing
+  autoload :SecurePassword
   autoload :Serialization
   autoload :TestCase
   autoload :Translation
diff --git a/activemodel/lib/active_model/secure_password.rb b/activemodel/lib/active_model/secure_password.rb
new file mode 100644
index 0000000000..0599ce6865
--- /dev/null
+++ b/activemodel/lib/active_model/secure_password.rb
@@ -0,0 +1,73 @@
+require 'digest/sha2'
+
+module ActiveModel
+  module SecurePassword
+    extend ActiveSupport::Concern
+
+    module ClassMethods
+      # Adds methods to set and authenticate against a SHA2-encrypted and salted password.
+      # This mechanism requires you to have password_digest and password_salt attributes.
+      # 
+      # Validations for presence of password, confirmation of password (using a "password_confirmation" attribute),
+      # and strength of password (at least 6 chars, not "password") are automatically added.
+      # You can add more validations by hand if need be.
+      #
+      # Example using Active Record (which automatically includes ActiveModel::SecurePassword):
+      #
+      #   # Schema: User(name:string, password_digest:string, password_salt:string)
+      #   class User < ActiveRecord::Base
+      #     has_secure_password
+      #   end
+      #
+      #   user = User.new(:name => "david", :password => "secret", :password_confirmation => "nomatch")
+      #   user.save                                                      # => false, password not long enough
+      #   user.password = "mUc3m00RsqyRe"                                
+      #   user.save                                                      # => false, confirmation doesn't match
+      #   user.password_confirmation = "mUc3m00RsqyRe"                   
+      #   user.save                                                      # => true
+      #   user.authenticate("notright")                                  # => false
+      #   user.authenticate("mUc3m00RsqyRe")                             # => user
+      #   User.find_by_name("david").try(:authenticate, "notright")      # => nil
+      #   User.find_by_name("david").try(:authenticate, "mUc3m00RsqyRe") # => user
+      def has_secure_password
+        attr_reader   :password
+        attr_accessor :password_confirmation
+
+        attr_protected(:password_digest, :password_salt) if respond_to?(:attr_protected)
+
+        validates_confirmation_of :password
+        validates_presence_of     :password_digest
+        validate                  :password_must_be_strong
+      end
+    end
+
+    module InstanceMethods
+      # Returns self if the password is correct, otherwise false.
+      def authenticate(unencrypted_password)
+        password_digest == encrypt_password(unencrypted_password) ? self : false
+      end
+
+      # Encrypts the password into the password_digest attribute.
+      def password=(unencrypted_password)
+        @password = unencrypted_password
+        self.password_digest = encrypt_password(unencrypted_password)
+      end
+
+      private
+        def salt_for_password
+          self.password_salt ||= self.object_id.to_s + rand.to_s
+        end
+
+        def encrypt_password(unencrypted_password)
+          Digest::SHA2.hexdigest(unencrypted_password + salt_for_password)
+        end
+        
+        def password_must_be_strong
+          if @password.present?
+            errors.add(:password, "must be longer than 6 characters") unless @password.size > 6
+            errors.add(:password, "can't be 'password'") if @password == "password"
+          end
+        end
+    end
+  end
+end
\ No newline at end of file
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