True or false: "In asymmetric encryption, the sender encrypts with their own private key."

False — the sender encrypts with the receiver's PUBLIC key. The receiver then decrypts with their own private key.

This is a classic mix-up. The correct flow:

Encryption (for confidentiality):

• Alice encrypts with Bob's public key $K_{pub,B}$
• Bob decrypts with his private key $K_{priv,B}$

Signing (for authentication — different operation!):

• Alice signs with her private key $K_{priv,A}$
• Bob verifies with Alice's public key $K_{pub,A}$

The confusion arises because:

• Both operations use asymmetric key pairs
• But the key usage is reversed: encryption uses the receiver's public key, signing uses the sender's private key

Memory aid:

• Encryption = lock for the receiver → use receiver's public key (anyone can lock, only receiver can unlock)
• Signing = personal stamp → use sender's private key (only sender can stamp, anyone can verify)