What security measure prevents unauthorized users from booting an encrypted hard drive?

Requiring entry of a startup password is a robust security measure that ensures only authorized users can access an encrypted hard drive upon booting. This entrance requirement acts as a barrier, preventing unauthorized users from bypassing security protocols and accessing sensitive data stored on the drive. By demanding a password at startup, this method secures the boot process and ensures that even if someone has physical access to the computer, they would not be able to decrypt or utilize the data without the correct password.

In contrast, enabling drive-level encryption alone may not prevent unauthorized access, especially if there are no measures in place to restrict how the system is booted. Disabling external USB devices does not directly affect the encrypted hard drive's boot process, nor does a non-TPM configuration inherently enhance security in this context. The use of a startup password specifically addresses the issue of unauthorized users attempting to access the system during the initial boot phase.