Skype have recently considered legal action against an individual whose team has claimed that they have reverse engineered one of the VoIP giant’s encryption algorithm.

Sean O’Neil, who is known for designing the EnRUPT algorithm, released code on his blog which emulates Skype’s RC4 encryption algorithm, used to protect communication between users on its network.

“We believe that the work being done by Sean O’Neil, who we understand was formerly known as Yaroslav Charnovsky, is directly facilitating spamming attacks against Skype and we are considering our legal remedies,”

This has raised some concerns amongst cryptoanalysts, since reverse engineering security measures is widely practiced in the industry, and has given open sourced algorithms like AES the benefit of a highly robust environment.

“There are seven types of communication encryption in Skype: its servers use AES-256, the supernodes and clients use three types of RC4 encryption – the old TCP RC4, the old UDP RC4 and the new DH-384 based TCP RC4, while the clients also use AES-256 on top of RC4. It all is quite complicated, but we’ve mastered it all,” O’Neil explains.