Question

Why do PGP and S/MIME need public key cryptography?

A) Public keys are necessary to determine whether
the e-mail is encrypted.
B) The public key is necessary to encrypt the
symmetric key.
C) The public key unlocks the password to the email.
D) The public key is useless and gives a false sense of
privacy.

Answer 1

PGP and S/MIME use public key cryptography to safely exchange a symmetric key, which is then used to encrypt the message content, ensuring that only the intended recipient can decrypt and read the message.

Step-by-step explanation:

PGP (Pretty Good Privacy) and S/MIME (Secure/Multipurpose Internet Mail Extensions) are protocols used to provide secure email communication. These protocols utilize public key cryptography because it enables users to exchange a symmetric key securely over an insecure medium.

The public key is used to encrypt this symmetric key, which is then used to encrypt the actual message content. Only the private key corresponding to the public key can decrypt the symmetric key, ensuring that only the intended recipient can read the message.

This system helps in maintaining privacy and security for personal, financial, and medical information, and it aids businesses and governments in keeping their operations and national security secrets safe.