Which property does a digital signature primarily provide to prove authorship and prevent denial of authorship?

Which property does a digital signature primarily provide to prove authorship and prevent denial of authorship?

• A. Non-repudiation
• B. Integrity
• C. Confidentiality
• D. Availability

Answer: (A)

Non-repudiation is what a digital signature primarily provides to prove authorship and prevent denial of authorship. When a signer creates a signature, they use their private key to sign a hash of the message. This binds the content to that specific key. Anyone who trusts the signer's public key (typically via a certificate in a PKI) can verify the signature and confirm it was created with the corresponding private key, which is assumed to belong to the signer. Because only the signer should hold that private key, they cannot credibly deny having signed the message later, establishing non-repudiation and accountability. The signature also ensures integrity—tampering with the message would produce a mismatch during verification—but the primary attribute described here is non-repudiation. Confidentiality and availability are not the primary purpose of a digital signature: confidentiality comes from encryption to keep content secret, and availability concerns system access and uptime rather than signing.

Non-repudiation is what a digital signature primarily provides to prove authorship and prevent denial of authorship. When a signer creates a signature, they use their private key to sign a hash of the message. This binds the content to that specific key. Anyone who trusts the signer's public key (typically via a certificate in a PKI) can verify the signature and confirm it was created with the corresponding private key, which is assumed to belong to the signer. Because only the signer should hold that private key, they cannot credibly deny having signed the message later, establishing non-repudiation and accountability.

The signature also ensures integrity—tampering with the message would produce a mismatch during verification—but the primary attribute described here is non-repudiation. Confidentiality and availability are not the primary purpose of a digital signature: confidentiality comes from encryption to keep content secret, and availability concerns system access and uptime rather than signing.