This setup posed challenges for users behind firewalls or Network Address Translation (NAT) because their connections could be used to facilitate calls between other clients.
In 2012, Microsoft transitioned control of supernodes to its data centers to enhance performance and scalability,[5][6] raising privacy concerns[7] that were later highlighted by the PRISM surveillance revelations in 2013.
The code remains closed-source,[12] and parts of the client utilize an open-source socket communication library called Internet Direct (Indy).
While their specific methods are proprietary, some published techniques include Pearson's chi-squared test and stochastic characterization using Naive Bayes classifiers.
The initialization vector (IV) is derived from a combination of the public source and destination IPs and a packet ID, transformed into an RC4 key.
However, EU law allows for reverse engineering for interoperability purposes,[16] and the U.S. Digital Millennium Copyright Act provides similar protections.