http://www.washingtonpost.com/busine...W_story_1.html

Skype’s resistance to government monitoring, part of the company ethos when European engineers founded it in 2003, resulted from both uncommonly strong encryption and a key technical feature: Skype calls connected computers directly rather than routing data through central servers, as many other Internet-based communication systems do. That makes it more difficult for law enforcement to intercept the call.

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Industry officials said the resulting push for the creation of so-called “supernodes,” which routed some data through centralized servers, made greater cooperation with law enforcement authorities possible.