So, according to some information coming from China, Skype can indeed be cloned.
In a previous post and in a column for the Wall Street Journal Europe in March I mentioned research done by Philippe Biondi and Fabrice Desclaux at EADS in France. The two scientists had reverse-engineered Skype -- the popular voice-over-IP service that lets you "phone" for free or near-free over the Internet -- and written a piece of software that "can assemble Skype packets and speak Skype": in other words, they could create an embryonic Skype clone that could interoperate with it (see for more their slides in PDF).
That was a first. Now, Charlie Paglee at VoipWiki reports that a Chinese company has also reverse-engineered Skype and cracked its protocols, creating a clone that allows for peer-to-peer phone calls. Paglee says that using his Skype client he could call twice with a friend who was using the "clone". He adds that the Chinese plan to create a client software 100 percent compatible with Skype (supporting presence info, instant messaging, etc).
Hard to say whether all this is authentic. But let's assume it is, since Biondi and Desclaux showed that it was possible: why does it matter? Because Skype has so far done all it could to keep the working of its protocols secret and opaque (Biondi and Desclaux call it "a total blackbox") and to hinder interoperability with other VoIP and IM clients. Its success (300 million downloads, 100 million users, bought by eBay last year for 2.6 billion USD - a figure that still has many people scratching their heads) is built on the closed system approach, and a clone - or an army of clones - could tear that open.
The Chinese clone apparently has another attribute: it does not support Skype's "supernode" architecture. To participate in the Skype network users have to accept to let Skype, if needed, turn their computer into a "supernode", holding portions of the database that contains the list of users and/or routing some traffic. That's the essence of Skype's "peer-to-peer" design (I've explained it in more details in another post). This is one of the main reasons why organizations such as CERN (the birthplace of the Web) have banned the use of Skype.
Now, if the Chinese have indeed figured out a way for users to take advantage of the Skype network without sharing computer power and connectivity, it could mean that the number of users "taking" could grow exponentially, while the number of those "giving" may shrink - a sort of parasitic use that could slow down or even disrupt the entire Skype network.
Skype may try legal actions, or release a new version of it software to strengthen its platform even more (for now they have just issued a statement saying that "no amount of reverse engineering would threaten Skype’s cryptographic security or integrity" - a very silly claim). Or it may decide to finally open up to interoperability. A reader on GigaOm called it "forcefully open source".