If you turn on content protection of master encryption keys, BlackBerry® devices use grand master keys to encrypt the master encryption keys that are stored in flash memory, and the BlackBerry devices store the decrypted grand master keys in RAM.

When you, a user, or the password timeout locks a BlackBerry device, the BlackBerry device continues to receive data and does not free the memory that is associated with the grand master key. If the BlackBerry device is locked and receives data that is encrypted with a master encryption key, the BlackBerry device uses the decrypted grand master key to decrypt the required master encryption key that is stored in flash memory and receive the data.