Exam CISA topic 1 question 45 discussion

A. Send a certificate that can be verified by a certification authority with the public key.

Option B does not verify the authenticity of the sender's public key, leaving the risk that someone using a forged key could send a message, thus requiring the use of certificates from a Certification Authority.

Answer: A

only the recipient could decrypt the message and get the sender's public key. Using the sender's public key, the recipient can reply the message under the same mechnism.

A. Send a certificate that can be verified by a certification authority with the public key. Sending a certificate that can be verified by a certification authority with the public key would be the best approach to prevent one person from using a fictitious key to impersonate someone else in a public-key cryptosystem. Certificates are used to bind a public key to a specific entity, and a certification authority's verification helps ensure the authenticity of the key. This approach establishes trust and prevents unauthorized individuals from using fake keys to impersonate legitimate parties.

Answer: A Since there is no previous connection, the initial link must be established via CA.

A, Sending a certificate that can be verified by a certification authority (CA) with the public key helps establish trust and authenticity.