Part 1 Suppose that Alice signs the message M love you\" and then encrypts it wi

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Part 1 Suppose that Alice signs the message M love you" and then encrypts it with Bob's public key before sending it to Bob. Bob can decrypt this to obtain the signed message and then encrypt the signed message with, say, Charlie's public key and forward the resulting ciphertext to Charlie. When Charlie receives the message he decrypts it and is amazed to see such a message which appears to come from Alice. What really went wrong here? Could Alice prevent this attack" by using symmetric key cryptography? [Hints: Refer to the lecture-9 and tutorial-9] Part Suppose Bob (the sender) wants to send a message m-5432 to Alice (the receiver). However, before sending the message he would like sign the message. When Alice receives the signed message, she would like to verify that the message is indeed from Bob. To facilitate signing and verification Bob generates public and private keys using ElGamal encryption algorithm and sends the public key to Alice. Bob chooses p-9721, g-1909, x-47. How would Bob sign message m-5432? How would Alice verify the signed message from Bob? Note You do not need to generate hash of the message m.]

Explanation / Answer

-->Here Bob and Alice are the transmitters

-->Suppose Bob read the data from Alice then whatever he likes thats only he can do with chunk of information.

-->And this cannot do by anyone and anything.

-->To prevent this one Alice can not do anything

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