PPTP remains a popular network protocol – especially on Windows computers - and it is one of the oldest protocols still in use. This has been developed by Microsoft to encapsulate another protocol called point-to-point. PPTP uses underlying authentication protocols such as MS-CHAP (Challenge Handshake Authentication Protocol (CHAP))—v1/v2, which are subject to serious security vulnerabilities. PPTP VPN encrypts data using 128-bit encryption, which makes it the fastest, but the weakest in terms of security.