John wants to send Marie an email that includes sensitive information, and he does not trust the network that he is connected to. Marie gives him the idea of using PGP. What should John do to…

Question

Options

• AUse his own public key to encrypt the message.
• BUse Marie's public key to encrypt the message.
• CUse his own private key to encrypt the message.
• DUse Marie's private key to encrypt the message.

• A
  2% (1)
• B
  86% (50)
• C
  3% (2)
• D
  9% (5)

Explanation

Using PGP (Pretty Good Privacy) encryption, John must encrypt the message with Marie's public key because only Marie possesses the corresponding private key needed to decrypt it - ensuring that only the intended recipient can read the sensitive content.

Why the distractors are wrong:

• A (John's public key): John's public key is meant for others to send John encrypted messages, not for John to send messages to Marie.
• C (John's private key): Using John's private key would create a digital signature (proving the message came from John), not encrypt the message for confidentiality - and anyone with John's public key could decrypt it, defeating the purpose.
• D (Marie's private key): Marie's private key is her secret and should never be shared; John would have no legitimate access to it.

Memory tip: Think of a public key as a padlock that anyone can use to lock (encrypt) a message, but only the owner of the matching private key can unlock (decrypt) it - so always encrypt with the recipient's public key.

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