var coding = 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMabcdefghijklmnopqrstuvwxyzabcdefghijklm';

function rot13(input) {
	if (!input) return '';
	for (var output = '',i=0;i<input.length;i++) {
		character = input.charAt(i);
		position = coding.indexOf(character);
		if (position > -1)
		character = coding.charAt(position + 13);
		output += character;
	}
	return output;
}