About encrypting data in the device memory
When encryption for the device memory is turned on, your BlackBerry® device uses a private key to encrypt data as it is stored on your device, including data that your device receives when it is locked. Your device decrypts data as you access it.
You can set encryption to include or exclude your contacts. If you turn on encryption for contacts and you receive a call when your device is locked, the caller name does not appear on the screen.
If you use a smart card certificate for authentication, depending on the smart card, you might also be able to use one of your smart card certificates to provide two-factor encryption. In order to access the encrypted content, you must provide your device password and also connect your device to your smart card reader.
When you lock your device, an open lock indicator appears at the top of the screen to indicate that your device is in the process of securing your data, which includes deleting a copy of the private key from the temporary device memory. A lock indicator appears at the top of the screen when your device has deleted the key.