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Difficulty: HardCIA Triad & Core Security Concepts

An enterprise network security administrator is establishing a secure procedure for receiving automated network device configuration updates from third-party vendor systems over an open network. The security policy dictates that the system must guarantee the configuration payload has not been modified during transmission and must also ensure that the vendor cannot deny having created and sent the specific configuration update. Which of the following mechanisms best fulfills both of these security requirements?

  1. Digitally signing the configuration payload using the vendor's private keyAnswer
  2. B
    Encrypting the configuration payload using a pre-shared AES-256 symmetric key
  3. C
    Generating a Hash-based Message Authentication Code (HMAC-SHA256) with a shared secret
  4. D
    Transporting the payload over standard TLS 1.3 with server-only certificate validation

Answer

Digitally signing the configuration payload using the vendor's private key
Digital signatures rely on asymmetric public key infrastructure (PKI). By hashing the configuration payload and signing the digest with the vendor's private key, the system ensures data integrity (any modification breaks the hash verification) and non-repudiation (only the owner of the private key could have signed it).

Step-by-Step Solution

1
Identify the required core security principles
The requirements are data integrity (verifying payload was not altered) and non-repudiation (preventing the sender from denying origin).
The scenario explicitly requests verification of payload contents and indisputable sender origin.
2
Evaluate symmetric key mechanisms against non-repudiation
Symmetric keys (such as AES-256 or HMAC pre-shared secrets) are shared between two endpoints. Since either party can create or alter the encrypted data/digest, neither mechanism satisfies non-repudiation.
Non-repudiation strictly requires asymmetric cryptography where only one unique entity possesses the private signing key.
3
Evaluate asymmetric digital signatures
The sender generates a hash digest of the configuration payload and encrypts it using their private key. The recipient validates integrity by computing the hash and decrypting the signature using the sender's public key.
Only the holder of the private key could have produced the signature, satisfying both integrity and non-repudiation.

Key Concept

Non-repudiation & Integrity in Security Architecture
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Topics

CIA Triad & Core Security Concepts

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