Summary: Cryptography specialists have developed tools to crack PPTP encryption (based on an algorithm from Microsoft), gaining access to Wi-Fi, passwords, corporate networks and data.
This website gives a good description about the Vigenère cipher and techniques for cracking it. It also shows another way we could more easily crack one of these ciphers using Microsoft Excel. Lastly, on the menu on the left side of the page is a link that lets you contact Simon Singh.