Question: a. Let ?? = 111... ... 111 be the DES key consisting of all 1s. Show that if ?? K (P) = C, then ??

a. Let ?? = 111... ... 111 be the DES key consisting of all 1s. Show that if ??_K(P) = C, then ??_K(C) = P, meaning encrypting twice with this key returns the plaintext.

Note: ??_K denotes Encryption function parameterized by a key, ??. ?? denotes plaintext and ?? denotes ciphertext.

[15 marks]

b. Find another key that has the same property as ?? in part (a).

[5 marks]

Step by Step Solution

There are 3 Steps involved in it

1 Expert Approved Answer

Step: 1 Unlock blur-text-image

Question Has Been Solved by an Expert!

Get step-by-step solutions from verified subject matter experts

Step: 2 Unlock

Step: 3 Unlock

Students Have Also Explored These Related Databases Questions!

Let K = 1 1 1 . . . 1 1 1 be the DES key consisting of all 1 s . Show that if EK ( P ) = C , then EK ( C ) = P , so encryption twice with this key returns the plaintext. ( Hint: The round keys are...

Eve captures Alice's affine cipher machine. She tries a chosen plaintext attack. She finds that the plaintext "NEW" encrypts to "UTV". Find both the encryption and decryption functions used by...

Question 3 Let K 11. 111 be the DES key consisting of all 1s. Show that if ER(P) C, then ER(C)P, so encryption twice with this key returns the plaintext

a. Let K = 111... ... 111 be the DES key consisting of all 1's. Show that if Ex(P) = C, then = EK(C) P, meaning encrypting twice with this key returns the plaintext. Note: Ex denotes Encryption...

a. Let K 111... 111 be the DES key consisting of all 1's. Show that if Ex(P)C, then Ex(C) P, meaning encrypting twice with this key returns the plaintext. Note: Ex denotes Encryption function...

HW2.doc 2.pdf This set of homework is for the contents covered in Chapter 3 Data Encryption Standard. 1. Answer the following concept questions about DES 1) What are the block size and key length? 2)...

4. What is the output LRi of the first round of the DES algorithm when the plaintext is a block of 1010 1010" (alternate one-zeros) and the key is "l 1 1 1 1 1 1 1" (all ones)? Please make sure that...

4. What is the output LRi of the first round of the DES algorithm when the plaintext is a block of 1010 1010" (alternate one-zeros) and the key is 1 1 1 1 1 1 1 1" (all ones)? Please make sure that...

5. For a bit string A, let A denote the complementary string obtained by changing all the 1s to 0s and all the 0s to 1s (equivalently, A = A 11111...). Show that if the DES key K encrypts x to y,...

Question 1 Suppose we define an encryption scheme as follows. The key will be four elements k 1, k 2, k 3, and k 4 in Z26. The message space will be sequences of elements of Z26 of length 6. The...

Medlar Corporation's static planning budget for June appears below. The company bases its budgets on machine-hours. Budgeted number of machine-hours 8,900 Supplies (@ $2.20 per machine-hour) $ 19,580...

Today, your manager asked you to provide information on three of the most common business services provided by the local public library. She has advised you that she needs this information by...

A flexible budget adjusts for changes in costs but not for changes in sales volume.Question 3 AnswerTrueFalse

What is hedging? Explain.

(Appendices) INTERNAL CONTROL FOR SALES. Gateway 2000 is a large mail-order computer and software business located in South Dakota. Most of Gateways customers call on its toll-free phone line and...

(Appendices) Why is the allowance procedure preferred over the direct write-off procedure for uncollectible accounts? LO77

(Appendices) SALES DISCOUNT POLICIES. Consider three businesses, all of which offer price reductions to their customers. The first is an independently owned Shell service station located at a busy...