P18. Suppose Alice wants to send an e-mail to Bob. Bob has a public-private key
ID: 3622588 • Letter: P
Question
P18. Suppose Alice wants to send an e-mail to Bob. Bob has a public-private key pair, and Alice has Bob’s certificate. But Alice does not have a public, private key pair. Alice and Bob (and the entire world) share the same hash function.a. In this situation, is it possible to design a scheme so that Bob can verify that Alice created the message? If so, show how with a block diagram for Alice and Bob.
b. Is it possible to design a scheme that provides confidentiality for sending the message from Alice to Bob? If so, show how with a block diagram for Alice and Bob.
Explanation / Answer
a) It is not possible to design a scheme,without public-private key pair,Bob cannot verify that Alice's e-mail message. b) It is possible to design a scheme that provides confidentiality for sending the message from Alice to Bob.Alice encrypts the message with Bob's public key and sends the encrypted message to Bob.
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