See here:
Mithun and Chetan explain it in their posts:
https://www-secure.symantec.com/connect/forums/what-exactly-recovery-key#comment-8687571
https://www-secure.symantec.com/connect/forums/what-exactly-recovery-key#comment-8750101
Contents of the Symantec Endpoint Protection 12.1 recovery file
http://www.symantec.com/docs/TECH162311