HP 2530p - EliteBook - Core 2 Duo 2.13 GHz Manuallines - Страница 7

How Preboot BIOS Implements the Password Filter And

Handles Dead Keys

The HP BIOS implements a second level password filter to further prevent the

lock‐out situation.

HP BIOS Preboot and HP Drive Encryption contain the keyboard mappings for

all the supported keyboards listed above. When a user is setting up Preboot

Security with the BIOS Preboot or Drive Encryption levels enabled, or when a

user changes his/her password, the BIOS Preboot and Drive Encryption

receives the Unicode password from the OS. The BIOS is responsible to

guarantee that the keyboard being associated with that user is able to type the

password. Otherwise, the BIOS will reject the password. However, there still

may be an instance where the user changes the keyboard in Windows without

the BIOS's knowledge or when the user is not aware of the keyboard layout

currently in use. To compensate for the situation where the user may not be

able to physically type their password due to these two situations, the BIOS will

automatically provide the user the ability to "click" out her/his password after

failing with the physical keyboard. This is done by showing every character on

the screen that could be typed with the keyboard currently associated with the

user, each of them as buttons and which can be clicked with the mouse to form

the password. This method provides a way for the user to enter the password

without the physical keyboard.

(Please note: When using the "On‐Screen Keyboard" in the BIOS, there are many characters shown and some characters

may look very similar to others on some keyboards. If experiencing trouble using this feature, so please look at all of

the characters before clicking out your password to ensure you are entering the correct characters.)

In the BIOS, the use of Dead Keys has also been added to try to provide the user

with as much keyboard functionality as possible. If for some reason a certain

character is produced on the OS level that cannot be typed in the BIOS, this will

cause the password change to be rejected. Unless rejected, the user should feel

safe and confident in using Dead Keys for passwords associated with the

Preboot Security feature.

This ability of the Preboot Security hinges on its ability to ensure that the

Windows password can always be entered in the Preboot BIOS and Drive

Encryption, and therefore all characters that require special typing methods

that are not common to all keyboards, such as the use of the Kana key or the use

of IME function of Windows, will result in the password change being rejected

from the BIOS, as the BIOS does not contain these advanced typing features.