Only move to quarantine folder action is taking place. No any cryptography algorithms used - very easy to run it again - just from another folder. Normally to quarantine the file mean to move it to special folder and make it nonrecoverable if recovery algorithms are not known to outside-the-product programs - it is much more securely (to damage/cryptography the file) to make it unworkable and save the ability to recover it.
Nowadays I have NIS 2011 with many quarantined files. Like older Norton 2010 and 2009 versions - any malware can execute quarantined (by Norton) files to make them run again.
Screens shows it - how easy to access quarantined files - as so easy to execute them again: non-Symantec "typical" program get access to files and can unpack it and potentially execute:
