Solution

In public key cryptography, both sender and receiver generate a pair of keys - Public key and Private key.

Public keys are known globally.

• Anything that is encrypted using public key of A can be decrypted only using private key of A.
• Anything that is encrypted using private key of A can be decrypted only using public key of A.
• Anything that is encrypted using public key of B can be decrypted only using private key of B.
• Anything that is encrypted using private key of B can be decrypted only using public key of B.

Hence, Sender encrypts using receiver's public key.