The Magento Encryption Key
You can find out the Magento Encryption Key during the installation. This key will be use for the storage and encryption of the most sensitive data in the database of scripts.This encryption key is kept in the file local.xml that reside in app/etc/local.xml. we can easily open this file using cPanel-> FileManager.
The encryption key code will be look like
Magento Encryption Key
The ENCRYPTION_KEY is the constant string that will replaced by the actual encryption key.
This key is very useful and will be use when you will like to move your store data to a new magento site. This key is used to recover all the encrypted data of magento site. Whenever you like to move your database content to new magento installation, you will need that key for new installation, written in local.xml file in new website. So you need to save this key otherwise old data will be lose.
You can find out more related article to magento here