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Zorluk: ZorCryptographic Concepts and Algorithms

A DevOps security architect is establishing an automated firmware distribution pipeline for remote edge devices operating on untrusted networks. The security baseline mandates a mechanism that guarantees payload data integrity, authenticates the vendor build system as the source, and provides non-repudiation so the authoring system cannot deny issuing a specific release. Which of the following cryptographic controls should the architect implement?

  1. A
    Symmetric payload encryption using AES-256 in Galois/Counter Mode (AES-256-GCM)
  2. Digital signatures created using the vendor build system's asymmetric private key over a SHA-256 digestCevap
  3. C
    Keyed-Hash Message Authentication Code (HMAC-SHA256) utilizing a global shared secret key distributed to all edge devices
  4. D
    Generation and attachment of a Certificate Signing Request (CSR) to each compiled firmware binary release

Cevap

Digital signatures created using the vendor build system's asymmetric private key over a SHA-256 digest
A digital signature is created by computing a cryptographic hash of the message (such as SHA-256) and encrypting that hash value using the sender's asymmetric private key. Recipients verify the signature using the corresponding public key. Because only the build server controls the private key, valid signatures provide proof of origin, data integrity, and non-repudiation.

Adım Adım Çözüm

1
Identify the required cryptographic properties from the scenario
The requirements explicitly call for data integrity, source authentication, and non-repudiation.
Non-repudiation requires a mechanism where only one specific entity possesses the private key used to sign the data.
2
Evaluate symmetric vs. asymmetric cryptographic mechanisms
Symmetric keys (such as AES-GCM or HMAC shared keys) are shared between sender and recipient, meaning recipient systems could forge payloads, which invalidates non-repudiation.
Asymmetric cryptography provides asymmetric key pairs (private/public), ensuring only the private key holder can create valid signatures.
3
Select the proper asymmetric implementation for firmware integrity and non-repudiation
Hashing the firmware with SHA-256 and encrypting the digest with the build server's private key forms a digital signature that edge devices verify using the public key.
This guarantees integrity (via SHA-256), source origin authentication, and non-repudiation (only the build server holds the private key).

Anahtar Kavram

Digital Signatures and Non-Repudiation
Tahmini Süre:2m 0s
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Cryptographic Concepts and Algorithms

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