Connect to SQL Server “Reporting Services Configuration Manager” from “All Programs”, provide the instance name and click on “Connect”.
Now click on “Encryption Keys” tab, which is second tab from bottom on left side of the window.
Here click on “Backup”
In the pop up window, we need to choose the file location and provide password for the file. Backup file will be of “.snk” extenstion.
Note: We need to know the password of the encryption key backup file to restore it. Without password encryption Key restore is not possible.
After clicking on “OK” and once backup completes you will see below message in the window: