How does public key cryptography work?

What will be an ideal response?

Under PK cryptography, each party has a pair of keys. One key is private and must not be shared with anyone, and the other key is public and accessible by anyone. Under PK cryptography, when Alice wants to send a secure message to Bob, she encrypts the message using Bob's public key and sends the encrypted message to Bob. Bob then uses his private key to decrypt the message. On the other hand, when Bob wants to send a secure message to Alice, he encrypts the message using Alice's public key and sends the encrypted message to Alice. Alice also uses her private key to decrypt the message. Even with both public keys and encrypted messages, an eavesdropper cannot decrypt the messages because neither of the private keys is available. Typical key lengths for the RSA key pair-generation algorithm are 1,024 bits. It is not feasible to derive one member of the key pair from the other key.