Question 2 (12 marks) (a). A Vigenere cipher with encryption key DELTA has been used to produce the ciphertext ZLPKEDQT. What was the plaintext? The following table is provided for your convenience: A B C D E F G H T j K L M N O P Q R S T U V w X Y Z 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 (bi). Alice wants to digitally sign the message [4,5] with help of RSA. She uses the public key (91, 29) and a private key 5. Compute the signed message. (bii). With the same RSA digital signature as in part (bi), Bob received a signed message [10] from Alice. What was the initial message? (c). Alice and Bob want to create a shared secret numbers with the help of the Diffie-Hellman protocol. Bob receives the triple (127,6, 17) from Alice. Then he chose the private key 3 and sent Alice the number 89. Computes. Question 2 (12 marks) (a). A Vigenere cipher with encryption key DELTA has been used to produce the ciphertext ZLPKEDQT. What was the plaintext? The following table is provided for your convenience: A B C D E F G H T j K L M N O P Q R S T U V w X Y Z 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 (bi). Alice wants to digitally sign the message [4,5] with help of RSA. She uses the public key (91, 29) and a private key 5. Compute the signed message. (bii). With the same RSA digital signature as in part (bi), Bob received a signed message [10] from Alice. What was the initial message? (c). Alice and Bob want to create a shared secret numbers with the help of the Diffie-Hellman protocol. Bob receives the triple (127,6, 17) from Alice. Then he chose the private key 3 and sent Alice the number 89. Computes