When you compress a database to an archive file you have the option of encrypting it with a password. You have to enter your password twice to avoid typos. The filename has the ending CBZ.
After you create an encrypted archive, the original database files are physically deleted! ChessBase asks you to confirm this, because the files can never be recovered. The program overwrites them with random characters before deleting them, to ensures that they cannot be reconstructed with disk utilities. So make sure you type in and remember the password correctly. Otherwise your database will be irrevocably lost.
ChessBase encrypts files using a powerful DES algorithm. There is also no secret master password or back door, and we cannot help you to retrieve files if anything goes wrong. So if you forget the password, your work is gone forever.