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Difficulty: EasyHardware and Embedded Systems Security

A manufacturer of medical IoT devices wants to permanently disable hardware debug interfaces, such as JTAG, prior to shipping devices to customers. This control must be executed at the silicon level so that hardware debugging cannot be re-enabled through software or firmware modifications. Which of the following hardware security mechanisms should the manufacturer use?

  1. Blowing an electronic fuse (eFuse) on the System-on-Chip during post-manufacturing provisioning.Answer
  2. B
    Setting a bootloader administrative password in the system software configuration settings.
  3. C
    Configuring a Trusted Platform Module to store platform configuration registers for remote attestation.
  4. D
    Encrypting the hardware debug bus communication streams using asymmetric AES-256 keys.

Answer

Blowing an electronic fuse (eFuse) on the System-on-Chip during post-manufacturing provisioning.
Blowing an eFuse provides a permanent, irreversible hardware-level change on the silicon itself. Because blowing a fuse physically breaks electrical traces inside the integrated circuit, it guarantees that debug interfaces such as JTAG cannot be re-enabled through subsequent firmware updates or software attacks.

Step-by-Step Solution

1
Identify the primary constraint specified in the scenario.
The requirement demands a permanent, irreversible silicon-level hardware control that prevents software from re-enabling debug ports.
Software controls or re-programmable memory can be tampered with if firmware is compromised.
2
Evaluate candidate hardware features against the requirement.
Electronic fuses (eFuses) write One-Time Programmable (OTP) bit states by permanently opening an internal electrical circuit on the chip.
Once an eFuse is blown, the physical link is severed forever, preventing any future firmware or software from re-enabling the debug interface.

Key Concept

eFuse and One-Time Programmable (OTP) Hardware Security Controls
Estimated Time:45s
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Topics

Hardware and Embedded Systems Security

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