According to CNET: “Skype was the only IM company that said it could not perform a live interception if presented with a wiretap request: "Because of Skype's peer-to-peer architecture and encryption techniques, Skype would not be able to comply with such a request.” Based on my preliminary research, documentation about Skype’s encryption and transport mechanisms appear to be outdated, inaccurate, or, in many cases, simply don't exist.
I suppose one can attribute some of that to the intentions of building a secure protocol (never mind the adage "security through obscurity is not security at all").
I scurried up to my lab and sought to reproduce Dula’s efforts.
The basic requirements for inspecting Skype’s SSL traffic and recording it are as follows: I registered a couple of dummy Skype accounts for testing, sent some traffic through Skype, and reviewed all my Skype packets to find that, in fact, they were encrypted.
To verify that my SSL traffic was in fact re-signed and decrypted by my SSL visibility appliance, I popped over to a few of my favorite test sites, Pay Pal and Facebook – and confirmed that, through the use of the SSL-VA, all SSL traffic was decrypted and sent to the SAP device in the clear.