A particular bank is using the following encryption scheme to transfer money from a user's account:...

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A particular bank is using the following encryption scheme to transfer money from a user's account: IV . (5 pts) First, give the equations for both encryption and encryption. . (10 pts) In more detail, when Alice is logged in and wants to transfer an amount to Bob, the bank creates an encrypted that when message the decrypted has form <Destination Account Amount>. For example, "100 Bob" would transfer 100KD to Bob's account. Assume the previous method is used to encrypt the message and each part is 1 block long. Further assume that Eve knows that Alice intents to transfer the money to Bob's account. Describe how Eve could construct a ciphertext C that when decrypted by the bank would transfer the money to her account. How about bankrupting Alice, i.e. transferring 10000KD to Bob's account? Notice that Eve does not have access to the secret key K used nor she can pick the IV. C₁ C₂ . K->> E R₁ P₁- K- E R₂--- P₂-0 (10 pts) Now suppose that in addition to C, the hash of P, is also transmitted, i.e the pair < Ci, Hash(P))> is sent for all i = 1, 2... In such a case, what is the check the receiver must perform upon decryption before accepting the message? Is this new method CCA2 secure? Proye your answer formally. A particular bank is using the following encryption scheme to transfer money from a user's account: IV . (5 pts) First, give the equations for both encryption and encryption. . (10 pts) In more detail, when Alice is logged in and wants to transfer an amount to Bob, the bank creates an encrypted that when message the decrypted has form <Destination Account Amount>. For example, "100 Bob" would transfer 100KD to Bob's account. Assume the previous method is used to encrypt the message and each part is 1 block long. Further assume that Eve knows that Alice intents to transfer the money to Bob's account. Describe how Eve could construct a ciphertext C that when decrypted by the bank would transfer the money to her account. How about bankrupting Alice, i.e. transferring 10000KD to Bob's account? Notice that Eve does not have access to the secret key K used nor she can pick the IV. C₁ C₂ . K->> E R₁ P₁- K- E R₂--- P₂-0 (10 pts) Now suppose that in addition to C, the hash of P, is also transmitted, i.e the pair < Ci, Hash(P))> is sent for all i = 1, 2... In such a case, what is the check the receiver must perform upon decryption before accepting the message? Is this new method CCA2 secure? Proye your answer formally.

Answer rating: 100% (QA)

Support my answer The encryption scheme you have described seems to be a simplified block cipher model The information provided and address your quest... View the full answer