Password

A password is a secret word or phrase known only to those who are given knowledge of it, to allow access into certain groups or places that are restricted from access to everyone else. In computer usage, it provides security unto the user to allow only the user access to private information.

Mainstream Smurfs Media
In the comic book version of "King Smurf" and the cartoon show episode "Smurfette's Dancing Shoes", passwords and special phrases were used by the Smurfs to allow only certain Smurfs who knew them into private gatherings.

Empath: The Luckiest Smurf stories
In the EMPATH: The Luckiest Smurf story series, passwords are used by Smurfs for security reasons. In the Smurf Village Imaginarium, Papa Smurf, Empath, and Polaris Psyche are given special access codes that lets them override private fantasy settings that are locked out to everyone else.

Private meetings between Smurfs may require passwords and special phrases known only to the Smurfs who are given them to be able to attend them.