View source for LuaTeX/Encrypt your document using ROT13

The following PlainTeX code example uses the ligaturing callback to "encrypt" the document using ROT13-"encryption".


  %&luatex
  
  % Notes:
  % 
  % -	Hyphenation is applied before rotating.
  % -	Ligaturing is performed after rotating.
  
  \pdfoutput=1
  \begingroup
  \catcode`\%=12
  \directlua0{
  	callback.register('ligaturing', function(head)
  		for v in node.traverse_id(33, head) do
  			if v.subtype == 1 then
  				local c = v.char
  				if c >= 65 and c <= 90 then
  					v.char = (c - 65 + 13) % 26 + 65
  				elseif c >= 97 and c <= 122 then
  					v.char = (c - 97 + 13) % 26 + 97
  				end
  			end
  		end
  		node.ligaturing(head)
  	end)
  }
  \endgroup
  
  % Hello World; fi -- fl -- ffl -- ffi -- enough with the ligatures!
  % Better do some kerning instead: AV
  
  Uryyb Jbeyq; sv -- sy -- ssy -- ssv -- rabhtu jvgu gur yvtngherf!
  Orggre qb fbzr xreavat vafgrnq: NI
  
  
  \bye


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