PPTP is a generic protocol that will support any encryption. However, he said he was unaware of some of Microsoft's NT 4.0 updates when he ran his tests. With relative ease, intruders can exploit the flaws, Schneier said, which he summarizes as weak authentication and poor encryption implementation. It's kindergarten cryptography. PPTP secures the packets sent via the Internet by encapsulating them in other packets.
Encryption is used to further secure the data contained in the packets.
It is the scheme Microsoft uses for this encryption that Schneier says is flawed. Confidential data is therefore compromised, he said. The nature of the flaws varied, but Schneier identified five primary ones. This is really surprising. Microsoft has good cryptographers in their employ.