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 communic

Encrypting with John's own public key would mean only John could decrypt it with his private key, making it unreadable by Marie.

PGP uses asymmetric key cryptography where the sender encrypts the message with the recipient's (Marie's) public key. Only Marie's corresponding private key can decrypt it, ensuring confidentiality even on an untrusted network. This is the fundamental asymmetric encryption workflow - public key encrypts, private key decrypts.

A private key in asymmetric cryptography is used for decryption (and digital signing), not for encrypting messages intended for another party.

Marie's private key must remain secret and is never shared; John would have no access to it, and using it for encryption would break the confidentiality model entirely.