Encrypting a database compacts the database file, and makes it indecipherable by a utility program or word processor. Encrypting a database doesn't restrict access to objects by users. Decrypting a database reverses the encryption.
You must either be the owner of the database or, if the database is secured, a member of the Admins group with Open Exclusive permission to encrypt or decrypt the database. It is recommended that you save a copy of your original database under a different name, drive, or folder before encrypting it. During the encryption process, Microsoft Access doesn't replace the original database until the encryption has been completed successfully. You must have enough storage space on your disk for both the original and the encrypted versions of the database.
Important You can't encrypt or decrypt a database when it is open.
On the Tools menu, point to Security, and then click Encrypt/Decrypt Database.
Specify the database you want to encrypt or decrypt, and then click OK.
If you use the same name, drive, and folder as the original database, and the database is encrypted or decrypted successfully, Microsoft Access automatically replaces the original file with the encrypted or decrypted version. If an error occurs, Microsoft Access doesn't delete the original file.