You can reset the farm pass phrase easily using the SharePoint 2010 Management Shell.
- Run SharePoint 2010 Management Shell using the appropriate credentials.
- Type in the following commands:
- $passphrase = ConvertTo-SecureString -asPlainText -Force
- Input your desired password, it must meet complexity requirements.
- Set-SPPassPhrase -PassPhrase $passphrase -Confirm
- Confirm by typing your password again.
- Confirm your action by pressing, Y and Enter.
There is no need to rejoin any servers to the farm or perform any reboots / IIS resets. The new farm pass phrase will be used when you join more servers to the farm in future.