Support PBKDF2 using SHA512 [updated]

lib/devise/encryptable/encryptable.rb

@@ -18,11 +18,12 @@ module Encryptors
       autoload :AuthlogicSha512, 'devise/encryptable/encryptors/authlogic_sha512'
       autoload :Base, 'devise/encryptable/encryptors/base'
       autoload :ClearanceSha1, 'devise/encryptable/encryptors/clearance_sha1'
+      autoload :Pbkdf2, 'devise/encryptable/encryptors/pbkdf2'
       autoload :RestfulAuthenticationSha1, 'devise/encryptable/encryptors/restful_authentication_sha1'
       autoload :Sha1, 'devise/encryptable/encryptors/sha1'
       autoload :Sha512, 'devise/encryptable/encryptors/sha512'
     end
   end
 end
 
-Devise.add_module(:encryptable, :model => 'devise/encryptable/model')
+Devise.add_module(:encryptable, :model => 'devise/encryptable/model')

lib/devise/encryptable/encryptors/pbkdf2.rb

@@ -0,0 +1,25 @@
+begin
+  module Devise
+    module Encryptable
+      module Encryptors
+        class Pbkdf2 < Base
+          def self.compare(encrypted_password, password, stretches, salt, pepper)
+            value_to_test = self.digest(password, stretches, salt, pepper)
+            Devise.secure_compare(encrypted_password, value_to_test)
+          end
+
+          def self.digest(password, stretches, salt, pepper)
+            hash = OpenSSL::Digest.new('SHA512').new
+            OpenSSL::KDF.pbkdf2_hmac(
+              password.to_s,
+              salt: "#{[salt].pack('H*')}#{pepper}",
+              iterations: stretches,
+              hash: hash,
+              length: hash.digest_length,
+            ).unpack1('H*')
+          end
+        end
+      end
+    end
+  end
+end