BitLocker™ Drive Encryption is a data protection feature integrated into Windows Vista™ that provides encryption for the entire O/S volume.
BitLocker provides three modes of operation:
The first two modes require a cryptographic hardware chip called a TPM 1.2 and a compatible BIOS:
Transparent operation mode
This mode leverages the capabilities of the TPM 1.2 hardware to provide for a seamless user experience – the user simply logs onto Windows Vista as normal. The key used for the disk encryption is sealed (encrypted) by the TPM chip and will only be released to the OS loader code if the early boot files appear to be unmodified. The pre-O/S components of BitLocker achieve this by implementing a Static Root of Trust Measurement – a methodology specified by the Trusted Computing Group.
User authentication mode
This mode requires that the user provide some authentication to the pre-boot environment in order to be able to boot the O/S. Two authentication modes are supported – a pre-boot PIN entered by the user or a USB device inserted that contains the required startup key.
The final mode does not require a TPM 1.2 chip:
USB-Key The user must insert a USB device that contains a startup key into the computer to be able to boot the protected O/S. Note that this mode requires that the BIOS on the protected machine supports the reading of USB devices in the pre-O/S environment.
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