In organizing a conference, a single key has to be used by all program committee members to encrypt and decrypt the message. Assuming this key has to be changed every year, how can you set up such a “session key” using public– private key pairs? Explain clearly.

Question

What will be an ideal response?

Answer 1

The organizer of the conference should generate a public-private key pair for each member and assign the private key to a corresponding member off line or personally. Once the session key needs to be setup or changed, the organizer encrypts the new session key by each member’s public key and sends it to the corresponding member. Each member uses its private key to decrypt the received message and obtain the new session key, which will be the same for all members; but the encrypted session key is different for each user.