Improve code style

app/controllers/xrd_controller.rb

@@ -31,9 +31,9 @@ class XrdController < ApplicationController
 
   def pem_to_magic_key(public_key)
     modulus, exponent = [public_key.n, public_key.e].map do |component|
-      result = ""
+      result = ''
 
-      until component == 0 do
+      until component.zero?
         result << [component % 256].pack('C')
         component >>= 8
       end
@@ -41,7 +41,7 @@ class XrdController < ApplicationController
       result.reverse!
     end
 
-    (["RSA"] + [modulus, exponent].map { |n| Base64.urlsafe_encode64(n) }).join('.')
+    (['RSA'] + [modulus, exponent].map { |n| Base64.urlsafe_encode64(n) }).join('.')
   end
 
   def resource_param