Set the proper S3 header for encryption.

lib/paperclip/storage/s3.rb

@@ -137,8 +137,8 @@ module Paperclip
           end
 
           @s3_headers[:storage_class] = @options[:s3_storage_class] if @options[:s3_storage_class]
-
-          @s3_server_side_encryption = @options[:s3_server_side_encryption]
+          @s3_headers['x-amz-server-side-encryption'] = @options[:s3_server_side_encryption].to_s.upcase if
+            @options[:s3_server_side_encryption]
 
           unless @options[:url].to_s.match(/^:s3.*url$/) || @options[:url] == ":asset_host"
             @options[:path] = @options[:path].gsub(/:url/, @options[:url]).gsub(/^:rails_root\/public\/system/, '')
@@ -302,9 +302,6 @@ module Paperclip
               :acl => acl
             }
             write_options[:metadata] = @s3_metadata unless @s3_metadata.empty?
-            unless @s3_server_side_encryption.blank?
-              write_options[:server_side_encryption] = @s3_server_side_encryption
-            end
             write_options.merge!(@s3_headers)
             s3_object(style).write(file, write_options)
           rescue AWS::S3::Errors::NoSuchBucket => e

test/storage/s3_test.rb

@@ -884,7 +884,7 @@ class S3Test < Test::Unit::TestCase
           object.expects(:write).with(anything,
                                       :content_type => "image/png",
                                       :acl => :public_read,
-                                      :server_side_encryption => :aes256)
+                                      'x-amz-server-side-encryption' => 'AES256')
           @dummy.save
         end