fix pdf

config/initializers/hexapdf.rb

@@ -11,6 +11,20 @@ module HexaPDF
         string_algorithm.encrypt(key, str).dup
       end
     end
+
+    module AES
+      module ClassMethods
+        def unpad(data)
+          padding_length = data.getbyte(-1)
+          if !padding_length || padding_length > BLOCK_SIZE || padding_length.zero? ||
+             data[-padding_length, padding_length].each_byte.any? { |byte| byte != padding_length }
+            data
+          else
+            data[0...-padding_length]
+          end
+        end
+      end
+    end
   end
 
   module Type