You can reset the farm pass phrase easily using the SharePoint 2010 Management Shell.

  1. Run SharePoint 2010 Management Shell using the appropriate credentials.
  2. Type in the following commands:
  3. $passphrase = ConvertTo-SecureString -asPlainText -Force
  4. Input your desired password, it must meet complexity requirements.
  5. Set-SPPassPhrase -PassPhrase $passphrase -Confirm
  6. Confirm by typing your password again.
  7. 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.