Google Cloud Professional Cloud Architect — Question 20

You are designing a mobile chat application. You want to ensure people cannot spoof chat messages, by providing a message were sent by a specific user.
What should you do?

Answer options

• A. Tag messages client side with the originating user identifier and the destination user.
• B. Encrypt the message client side using block-based encryption with a shared key.
• C. Use public key infrastructure (PKI) to encrypt the message client side using the originating user's private key.
• D. Use a trusted certificate authority to enable SSL connectivity between the client application and the server.

Correct answer: C

Explanation

The correct answer is C because using public key infrastructure (PKI) and encrypting the message with the originating user's private key ensures that only that user could have sent the message, preventing spoofing. Option A does not provide sufficient security as client-side tagging can be easily manipulated. Option B, while it encrypts the message, does not authenticate the sender. Option D is focused on secure communication but does not address message authenticity.