Skype Protocol Cracked?

The hugely popular voice-over-IP (VoIP) software, Skype, uses a proprietary protocol that has remained secret. But now a Chinese company has reportedly reversed engineered the protocol for Skype and plans to release compatible software in the near future.

The alleged reverse engineering feat was initially reported by Charlie Paglee, who operates the VOIPWIKI blog. Paglee said that an employee at the unnamed Chinese company contacted him and conducted a test VoIP call to prove that the reverse engineering is taking place.

"At present [the software] only [supports] placing Skype peer-to-peer phone calls and [the company has] not yet implemented presence. They have plans to add presence, instant messaging, and a host of other features. Their end goal is to create a client 100% compatible with Skype," Paglee wrote in his blog entry dated July 13, 2006.

Paglee added that "[The company] developed Skype blocking technology which they claim is fool-proof and extremely effective." The blocking technology could allow anyone to completely prohibited the use of Skype on their networks.

Writing in his independent Skype Journal, Phil Wolff said that in order to reverse engineer the software the Chinese developers had to figure out how to "see and navigate through the Skype cloud, to find a Skype client; publish their own client's profile into the Skype cloud, so a Skype client could find them; and negotiate starting the call session, including encryption"

One major difference between the official Skype software and the technology being developed by the Chinese company is bandwidth utlization. Skype's software includes "super node" functionality, which essentially relies on the networks of Skype users to facilitate calls under certain conditions when Skype users are behind firewalls.

Paglee said the super node technology effective highjacks bandwidth of third parties so that other people can communicate with Skype. The Chinese company's software will not include super node functionality, which could make the software more appealing than Skype's official software. Skype's end user license agreement (EULA) does disclose the possible use of client's processor time and bandwidth. In the EULA it is stated that "You hereby acknowledge that the Skype Software may utilize the processor and bandwidth of the computer (or other applicable device) You are utilizing, for the limited purpose of facilitating the communication between Skype Software users.”

The opening of the Skype protocol will likely lead to many developers, including those from the company's that produce the major instant messaging clients, looking for ways to integrate Skype compatibility into their applications. According to Paglee, three unnamed IM companies have already inquired with the Chinese company about licensing.

Online auction powerhouse eBay acquired Skype in September 2005 for $2.6 billion in up-front cash and eBay stock, plus potential performance-based consideration. A spokesperson for Skype reportedly issued a statement saying, "Skype is aware of the claim made by a small group of Chinese engineers that they have reverse engineered Skype software. We have no evidence to suggest that this is true. Even if it was possible to do this, the software code would lack the feature set and reliability of Skype which is enjoyed by over 100 million users today. Moreover, no amount of reverse engineering would threaten Skype’s cryptographic security or integrity."