What is a digital signature primarily used for?

• A. To encrypt keys during transmission
• B. To verify the integrity of a document
• C. To create public and private key pairs
• D. To manage access control in networks

Answer: (B)

A digital signature is primarily used to verify the integrity of a document. When a document is signed digitally, a hash of the document is generated and then encrypted with the sender's private key, creating a unique signature that is attached to the document. This process ensures that if the document is altered in any way after being signed, the hash will not match when it is decrypted and verified using the sender's public key. Thus, recipients can be confident that the document has not been tampered with since it was signed, confirming both its authenticity and integrity.

In contrast, although encryption keys can be involved in the broader context of digital signatures, their primary purpose is not to encrypt keys during transmission. Digital signatures also do not involve the creation of public and private key pairs directly, as this process is distinct and typically associated with asymmetric encryption. Finally, while access control is an important aspect of network security, digital signatures do not play a direct role in managing access control; rather, they focus on ensuring data integrity and authenticity in communications.