Switch from SHA2 to BCrypt (easy Windows compatibility is coming shortly with new compiled gem)

activemodel/CHANGELOG

 *Rails 3.1.0 (unreleased)*
 
-* Added ActiveModel::SecurePassword to encapsulate dead-simple password usage with SHA2 encryption and salting [DHH]
+* Added ActiveModel::SecurePassword to encapsulate dead-simple password usage with BCrypt encryption and salting [DHH]
 
 
 *Rails 3.0.2 (unreleased)*

activemodel/activemodel.gemspec

@@ -22,4 +22,6 @@
   s.add_dependency('activesupport', version)
   s.add_dependency('builder',       '~> 3.0.0')
   s.add_dependency('i18n',          '~> 0.5.0')
+  s.add_dependency('bcrypt-ruby',   '~> 2.1.2')
+  
 end

activemodel/lib/active_model/secure_password.rb

-require 'digest/sha2'
+require 'bcrypt'
 
 module ActiveModel
   module SecurePassword
@@ -44,13 +44,17 @@ def has_secure_password
     module InstanceMethods
       # Returns self if the password is correct, otherwise false.
       def authenticate(unencrypted_password)
-        password_digest == encrypt_password(unencrypted_password) ? self : false
+        if BCrypt::Password.new(password_digest) == (unencrypted_password + salt_for_password)
+          self
+        else
+          false
+        end
       end
 
       # Encrypts the password into the password_digest attribute.
       def password=(unencrypted_password)
         @password = unencrypted_password
-        self.password_digest = encrypt_password(unencrypted_password)
+        self.password_digest = BCrypt::Password.create(unencrypted_password + salt_for_password)
       end
 
       private
@@ -58,10 +62,6 @@ 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

activerecord/CHANGELOG

 *Rails 3.1.0 (unreleased)*
 
-* Added ActiveRecord::Base#has_secure_password (via ActiveModel::SecurePassword) to encapsulate dead-simple password usage with SHA2 encryption and salting [DHH]. Example:
+* Added ActiveRecord::Base#has_secure_password (via ActiveModel::SecurePassword) to encapsulate dead-simple password usage with BCrypt encryption and salting [DHH]. Example:
 
     # Schema: User(name:string, password_digest:string, password_salt:string)
     class User < ActiveRecord::Base