FileVault recovery key
A recovery key is a combination of numbers and letters that you must record and keep track of yourself. Keep a copy of this key somewhere other than your encrypted startup disk. If you write the key down, be sure to copy the letters and numbers exactly as they’re shown, and keep it somewhere safe that you’ll remember.
Important: Don’t keep the recovery key with your Mac where it can be discovered by others.
If you see the message “A recovery key has been set by your company, school, or institution,” the administrator for your organization has created a recovery key for this Mac. If you forget your password and need to unlock your encrypted Mac, ask your administrator to unlock it with the recovery key, then reset your password.