QUESTION 2 a) Assume that k = 3 and n = 5. Then the list of datawords and codewoards are given as follows: Dataword Codeword 000 00000 010 01001 011 01100 101 10101 Assume the sender encodes the dataword 010 as 01001 and sends it to the receiver. Explain the following scenario. i. The receiver receives 01001. ii. The receiver receives 01101. 11. The receiver receives 00000. b) Identify the type of error for the following situation. i. A sender sends 01001 and the receiver receives 01101. 11. A sender sends 01001 and the receiver receives 00000.

QUESTION 2 a) Assume that k = 3 and n = 5. Then the list of datawords and codewoards are given as follows: Dataword Codeword 000 00000 010 01001 011 01100 101 10101 Assume the sender encodes the dataword 010 as 01001 and sends it to the receiver. Explain the following scenario. i. The receiver receives 01001. ii. The receiver receives 01101. 11. The receiver receives 00000. b) Identify the type of error for the following situation. i. A sender sends 01001 and the receiver receives 01101. 11. A sender sends 01001 and the receiver receives 00000.

Systems Architecture

7th Edition

ISBN:9781305080195

Author:Stephen D. Burd

Publisher:Stephen D. Burd

Chapter8: Data And Network Communication Technology

Section: Chapter Questions

Problem 41VE

See similar textbooks

Similar questions

When Bob wants to send Alice a message M on the Internet, he breaks M into n data packets, numbers the packets consecutively, and injects them into the network. When the packets arrive at Alice’s computer, they may be out of order, so Alice must assemble the sequence of n packets in order before she can be sure she has the entire message. Describe an efficient scheme for Alice to do this. What is the running time of this algorithm? From Data Structures and Algorithms C-7.56
1-The eficiency of 64 equiprobable messages coded in fixed length i . a9 b 9l00% AP 2+ Ihe effciency of 17 cquiprobable messages coded in a fixed lengh wil be approximately—— WI00% B)20% 8% d)non ofthe mentioned 3- The average code lengih L f 10 equiprobuble messages coded in a ixed length il be - 1 W2 94 dnonofthe mentioned 4 For 11 cquiprobable messages coded in fixed ength cod then 5- For 256 equiprobable messsges coded in fxed length code then
**Please do A or C** a. Compute CBC-MAC for a message of 16 bits, “8642” (in Hexa). Assume a block size of 8 bits with an IV=F1 (in hexa). For simplicity, assume the encryption to be a simple XOR of the key with the plaintext. Let the encryption key be B4 (in Hexa). (Hint: Divide the message into blocks of 8 bits each; XOR each block with the previous cipher output; then encrypt this with the key. For the first block, XOR it with IV. Details in pages 325-326 Ch.12 of the textbook) b. Suppose Alice computes the Secret prefix MAC (page 322: secret prefix MAC(x) = h(key || x)) for the message ”AM” (in ASCII) with key “G” (in ASCII) that both Alice and Bob know. The hash function that is used is h(x1x2x3)= g(g(x1 XOR x2) XOR x3 ) where each xi is a character represented as 8 bits, and g(x) is a 8-bit string that is equal to the complement of bits in x. For example, g(10110011) = 01001100. The MAC is 8 bits. (8-bit ASCII representation of the characters is given below.) What is the…
above question : Suppose that we have the following 128-bit AES key, given in hexadecimalrepresentation:54 77 6F 20 4F 6E 65 20 4E 69 6E 65 20 54 77 6F Construct the round key for the first round. Main Question: Complete the first round of the encryption (128-bit AES) of the following plaintext by using the round-key you generated above:63 72 79 70 74 61 6e 61 6c 79 73 69 73 6f 6e 65
Give answer of both subparts. (Don't use AI)
Alice is using the one-time pad and notices that when her key is all-zeroes ? = 0^?, then Enc(?, ?) = ? and her message is sent in the clear! To avoid this problem, she decides to modify the scheme to exclude the all-zeroes key. That is, the key is now chosen uniformly from {0, 1}^?\ {0^?}, the set of all ?-bit strings except 0^? . In this way, she guarantees that her plaintext is never sent in the clear. Is this variant still one-time perfectly secure? Justify your answer.
1. We have defined a symmetric cryptography algorithm using the XOR operator. Assume our messages (before encryption) consist of only uppercase and lowercase letters, digits and blank character. In addition, assume the key size is only one byte which is an integer between 0 and 255 (inclusive). The pseudocode of the proposed encryption algorithm is as follows: Read the message // for example message=”Hi” Read the key // for example key=10 Cipher_text=[] //an empty list for i=1 to len(message): Cipher_text= Cipher_text.append(XOR(message[i],key)) Return Cipher_text Assume XOR function, takes a character and the key, then returns the result of bitwise XOR of ASCII code of the letter with the key as an (one byte) integer. For example, if message=”Hi” and key=10, then we should first calculate the ASCCI code of “H” which is 72 and find the result of (72 XOR 10) which is 66. Then the ASCCI code of “i” is 105, so the result of (105 XOR 10) is 99. Thus the Cipher_text would be…
1. We have defined a symmetric cryptography algorithm using the XOR operator. Assume our messages (before encryption) consist of only uppercase and lowercase letters, digits and blank character. In addition, assume the key size is only one byte which is an integer between 0 and 255 (inclusive). The pseudocode of the proposed encryption algorithm is as follows: Read the message // for example message=”Hi” Read the key // for example key=10 Cipher_text=[] //an empty list for i=1 to len(message): Cipher_text= Cipher_text.append(XOR(message[i],key)) Return Cipher_text Assume XOR function, takes a character and the key, then returns the result of bitwise XOR of ASCII code of the letter with the key as an (one byte) integer. For example, if message=”Hi” and key=10, then we should first calculate the ASCCI code of “H” which is 72 and find the result of (72 XOR 10) which is 66. Then the ASCCI code of “i” is 105, so the result of (105 XOR 10) is 99. Thus the Cipher_text would be…
1. (A=0,Z=25) Encode: BE HONEST using the encrypting function f (p) = (p+ 3) mod 26. 2. Decode: GPWJO if the original message was encrypted using f (p) = (7p+ 10) mod 26. 3. What is the 6th term in the following sequence? 11, 15, 19, 23, ___, Blank 1 4. Using the Euclidean algorithm to compute for the gcd (1283, 7295), what is the value of the last nonzero remainder? 5. Is the given integer 9321 a prime or composite?
Assume you are using any correct plaintext padding method, such as those described in lecture, with a 128-bit (16-byte) block cipher. If you are sending a message that is 184 bytes long, how many padding bytes would you need to add? Justify your answer. For the remaining questions, consider a 4-bit block cipher, described in hexadecimal by the following table: Plaintext Ciphertext Plaintext Ciphertext 0 a 8 e 1 c 9 d 2 f a 0 3 6 b 7 4 3 c 5 5 8 d b 6 4 e 9 7 2 f 1 You can think of this as a simple substitution cipher for hexadecimal digits. There is no “key” other than the table itself.
The following message uses a direct mapping of letters to numbers (i.e. A-1, B=2, c-3, etc.).Using the values D=17 and m=21, decrypt the following message:10 15 12 18 1 3 17 14 7 18 14 17 17 9 18 14
How many 14-bit strings (that is, bit strings of length 14) are there with: (a) start with sub-string 011? (b) have weight 7 (i.e., contain exactly 7 1’s) and start with the sub-string 011? (c) either start with 011 or end with 01 (or both)? (d) have weight 7 and either start with 011 or end with 01 (or both)?