You may know about Punycode, a way to represent Unicode strings with only ASCII characters. It is used to encode domain names, for example “münchen.de” becomes “xn--mnchen-3ya.de”. Punycode, specified in RFC 3492, is technically just a set of parameters for a more general algorithm called Bootstring, which is specified in the same document. In this post, I will explain how Bootstring works and how to use it to decode an encoded string.
