You can change your keys at any time, but you must change both keys at the same time.
To change your keys, complete the following steps:
Select Add-ons from the Jira Administration icon.
Click Change Keys under Encryption for Jira in the left sidebar.
Enter the old key, then enter a new key, or click Generate to auto-generate a key. Do this for every key you want to change.
If you are creating your own keys instead of using the auto-generate option, please note that keys must be entered in hexadecimal format.