CFPropertyList: Format error! (CFFormatError)

error_dump

[15:18:01] bcw$ ~/Desktop/foo.rb 
/Library/Ruby/Gems/2.0.0/gems/CFPropertyList-2.2.5/lib/rbREXMLParser.rb:101:in `block in import_xml': Format error! (CFFormatError)
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rexml/element.rb:905:in `block in each'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rexml/xpath.rb:67:in `each'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rexml/xpath.rb:67:in `each'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rexml/element.rb:905:in `each'
	from /Library/Ruby/Gems/2.0.0/gems/CFPropertyList-2.2.5/lib/rbREXMLParser.rb:93:in `import_xml'
	from /Library/Ruby/Gems/2.0.0/gems/CFPropertyList-2.2.5/lib/rbREXMLParser.rb:102:in `block in import_xml'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rexml/element.rb:905:in `block in each'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rexml/xpath.rb:67:in `each'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rexml/xpath.rb:67:in `each'
	from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rexml/element.rb:905:in `each'
	from /Library/Ruby/Gems/2.0.0/gems/CFPropertyList-2.2.5/lib/rbREXMLParser.rb:93:in `import_xml'
	from /Library/Ruby/Gems/2.0.0/gems/CFPropertyList-2.2.5/lib/rbREXMLParser.rb:23:in `load'
	from /Library/Ruby/Gems/2.0.0/gems/CFPropertyList-2.2.5/lib/rbCFPropertyList.rb:347:in `load'
	from /Library/Ruby/Gems/2.0.0/gems/CFPropertyList-2.2.5/lib/rbCFPropertyList.rb:247:in `initialize'
	from /Users/bcw/Desktop/foo.rb:8:in `new'
	from /Users/bcw/Desktop/foo.rb:8:in `<main>'

foo.rb

#!/usr/bin/ruby
require 'rubygems'
require 'cfpropertylist'

file = '/System/Library/Security/authorization.plist'

plist = CFPropertyList::List.new(:file => file)
CFPropertyList.native_types(plist.value)