Certified Ethical Hacker (CEH v11) — Question 158

What is correct about digital signatures?

Answer options

• A. A digital signature cannot be moved from one signed document to another because it is the hash of the original document encrypted with the private key of the signing party.
• B. Digital signatures may be used in different documents of the same type.
• C. A digital signature cannot be moved from one signed document to another because it is a plain hash of the document content.
• D. Digital signatures are issued once for each user and can be used everywhere until they expire.

Correct answer: A

Explanation

The correct answer is A, as a digital signature is uniquely tied to the specific document it signs, involving the hashing of the document and encryption with the private key, making it non-transferable. Option B is incorrect because while digital signatures can be used across documents of the same type, they are still document-specific. Option C is wrong since it incorrectly describes a digital signature as merely a plain hash, ignoring the encryption aspect. Option D is misleading as digital signatures are not universally valid; they are bound to the document they sign and may have expiration conditions.