Facebook is working on implementing a security measure that would would make eavesdropping on your encrypted traffic with the website extremely difficult. Facebook uses encryption keys with a length of only 1024 bits with HTTPS connection and now planning to change the length of the keys on all of its SSL certificates to 2048 bits. The change in key length makes it much harder for an attacker to use known methods to break the key. The new technique is an advanced form of HTTPS that throws away the master key and essentially makes a new key every time someone connects.
Source: https://thehackernews.com/2013/06/facebook-implementing-advanced-https-to.html