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Question

Difficulty: HardInformation Technology and Cybersecurity

Consider the following statements regarding Public Key Infrastructure (PKI) and digital signature mechanisms:

1. A digital signature ensures non-repudiation and data integrity, but it does not inherently provide message confidentiality.
2. The Online Certificate Status Protocol (OCSP) allows real-time verification of a digital certificate's revocation status without requiring the download of complete Certificate Revocation Lists (CRLs).
3. In asymmetric cryptography, a sender encrypts a message with their own private key to ensure confidentiality for the intended recipient.

Which of the statements given above is/are correct?

  1. 1 and 2 onlyAnswer
  2. B
    1 and 3 only
  3. C
    2 and 3 only
  4. D
    1, 2 and 3

Answer

The statements asserting that digital signatures provide non-repudiation and integrity without inherent confidentiality (Statement 1) and that OCSP enables real-time certificate status verification compared to CRLs (Statement 2) are correct. The statement regarding private key encryption for confidentiality (Statement 3) is incorrect.
Statements 1 and 2 are accurate. A digital signature verifies origin and prevents tampering but does not hide the content from third parties. OCSP provides live, real-time revocation checks per certificate, improving on CRL download overhead. Statement 3 is wrong because recipient confidentiality requires encryption using the recipient's public key.

Step-by-Step Solution

1
Analyze Statement 1 regarding digital signature security services.
Digital signatures are created by hashing data and encrypting the hash with the sender's private key. This guarantees integrity and non-repudiation. However, the plaintext payload remains unencrypted unless symmetric/asymmetric encryption is added.
Verify if confidentiality is an inherent property of digital signatures.
2
Analyze Statement 2 regarding PKI certificate revocation protocols.
CRL requires downloading complete, potentially large lists of revoked certificates periodically. OCSP sends a lightweight request for a single certificate status directly to an OCSP responder in real time, making it faster and less bandwidth-intensive.
Compare CRL and OCSP certificate revocation checking mechanisms.
3
Analyze Statement 3 regarding asymmetric key cryptography for confidentiality.
To achieve confidentiality, data must be encrypted using the recipient's public key, ensuring only the recipient holding the corresponding private key can decrypt it. Encrypting with a sender's private key provides authentication/signature, not confidentiality.
Identify the proper key selection for message encryption.

Key Concept

Public Key Infrastructure, Asymmetric Cryptography Key Usage, and Certificate Revocation Protocols
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Topics

Information Technology and Cybersecurity

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