Discuss the functionality of S/MIME.

The basic functionalities of S/MIME are :

Enveloped Data:

• Think of it like putting your message in a sealed envelope.
• The message is encrypted, and the encryption key is also enclosed, but this key is itself encrypted using the receiver’s public key.
• Only the recipient with the right key can open the envelope and read the message.

Signed Data:

• Imagine signing a letter with your unique signature.
• The message digest (a kind of summary) is encrypted with your private key, creating a digital signature.
• Only those with S/MIME capability can open and read the signed message, ensuring it’s from you.

Clear-Signed Data:

• Similar to signed data, but this time the message content is visible without needing S/MIME.
• Anyone can read the message, but they can’t verify the signature without S/MIME capability.

Signed and Enveloped Data:

• Combines the sealed envelope and the signature.
• The message is both encrypted and signed, providing a secure and verified communication.
• Allows flexibility by nesting signed-only and encrypted-only elements.