ISC2 CISSP (Certified Information Systems Security Professional)Security Architecture and EngineeringMedium
A manufacturing facility is upgrading its Industrial Control Systems (ICS) and is concerned about supply chain attacks compromising firmware before deployment. They need a mechanism to cryptographically verify the authenticity and integrity of firmware updates received from vendors. Which cryptographic method is essential for achieving this goal?
- AOne-Time Pad for ultimate secrecy.
- BDigital Signatures for code signing.
- CSymmetric Key Exchange protocols.
- DStream Ciphers for fast encryption.
Show answer & explanationAnswer & explanation
Correct answer: B. Digital Signatures for code signing.
Digital signatures are crucial for verifying the authenticity and integrity of firmware updates. The vendor signs the firmware with their private key, and the ICS system uses the vendor's public key to verify the signature, ensuring the update came from a legitimate source and hasn't been tampered with.
Why the other options are wrong
- A. One-Time Pad is for perfect secrecy of messages, impractical for firmware updates and doesn't provide authenticity.
- C. Symmetric key exchange establishes shared secrets but doesn't provide non-repudiation or integrity for arbitrary files.
- D. Stream ciphers are for confidentiality of data streams, not integrity/authenticity of files.
Digital Signatures
A mathematical scheme for demonstrating the authenticity and integrity of digital messages or documents.
- Uses asymmetric cryptography: sender signs with private key, receiver verifies with public key.
- Provides authenticity (origin), integrity (not altered), and non-repudiation (sender cannot deny).
- Essential for code signing, secure software updates, and legal electronic documents.
Memory trick: Firmware needs a digital signature, like a trusted stamp.