What does a digital signature provide?

• A. Nonrepudiation and integrity
• B. Confidentiality
• C. Randomization
• D. Public-key discovery

Answer: (A)

Digital signatures primarily provide integrity and nonrepudiation. When the signer uses their private key to generate a signature over a hash of the message, anyone with the signer’s public key can verify that the signature matches the exact content. If the message is altered after signing, the verification will fail, demonstrating that tampering did not occur and preserving integrity. Nonrepudiation comes from the fact that only the signer who holds the private key could create that signature, and a trusted certificate links that key to the signer’s identity, preventing the signer from denying authorship later. Confidentiality, the ability to keep content secret, is not provided by a signature alone and requires encryption. Randomization is not a purpose of digital signatures, and public-key discovery is about obtaining the correct public key for verification, which is a separate step from the signing process.