Certified Information Systems Auditor (CISA) — Question 1279

Which of the following is a characteristic of a digital signature used for securing email transmissions?

Answer options

• A. The signed message provides confidentiality and availability protection.
• B. The signature on one message can be transferred to another message.
• C. The signature is authentic whether or not it has been encrypted.
• D. The receiver only needs the public key to decrypt the message and verify the signature.

Correct answer: C

Explanation

Option C is correct because a digital signature remains valid and authentic whether it is encrypted or not. Option A is incorrect as digital signatures primarily provide authentication and integrity, not confidentiality and availability. Option B is wrong because signatures are unique to each message and cannot be transferred. Option D is misleading since the public key is used for verification, not decryption of the message itself.