Amount $ 20
cart 0
Question Preview:
(a) 2 points List and briefly define categories of passive and active security attacks.
Total for Question 1: 2
2. Classic Encryption
(a) 1 points What are the two basic functions used in encryption algorithms?
(b) 1 points What are the two general approaches to attacking a cipher?
(c) 2 points List and briefly define types of cryptanalytic attacks based on what is known to the
attacker.
(d) 2 points What are two problems with the one-time pad?
(e) 2 points Calculate the determinant mod 26 of
20 2
5 4
.
(...
Question Preview:
(a) 2 points List and briefly define categories of passive and active security attacks.
Total for Question 1: 2
2. Classic Encryption
(a) 1 points What are the two basic functions used in encryption algorithms?
(b) 1 points What are the two general approaches to attacking a cipher?
(c) 2 points List and briefly define types of cryptanalytic attacks based on what is known to the
attacker.
(d) 2 points What are two problems with the one-time pad?
(e) 2 points Calculate the determinant mod 26 of
20 2
5 4
.
(f) 3 points Encrypt the message “meet me” using the Hill cipher with the key
9 4
5 7
. Show your
calculations and the result.
(g) 3 points Show the calculations for the corresponding decryption of the ciphertext in above part
to recover the original plaintext.
(h) 2 points Using the Vigenere cipher, encrypt the word “explanation” using the key “leg”.
(i) 5 points The following ciphertext was generated using a simple substitution algorithm. Given that
the plaintext is in English language, can you decrypt this message by exploiting the characteristics
of English Language (eg, alphabet e is the most recurring in plain text).
53305))6*;4826)4.)4);806*;48860))85;;]8*;:*883 (88)5*;46(;88*96*?;8)*(;485);5*2:*(;4956*2(5*4)88*
;4069285);)68)4;1(9;48081;8:81;4885;4)485528806*81 (9;48;(88;4(?34;48)4;161;:188;?;
Total for Question 2: 21
3. One Time Pad This problem explores the use of a one-time pad version of the Vigenre cipher. In this
scheme, the key is a stream of random numbers between 0 and 26. For example, if the key is 3 19 5
· · · , then the first letter of plaintext is encrypted with a shift of 3 letters, the second with a shift of 19
letters, the third with a shift of 5 letters, and so on.
(a) 3 points Encrypt the plaintext “sendmoremoney” with the key stream
9 0 1 7 23 15 21 14 11 11 2 8 9
(b) 3 points Using the ciphertext produced in part (a), find a key so that the cipher text decrypts
to the plaintext “cashnotneeded”.
Total for Question 3: 6
4. Block Ciphers
(a) 3 points Which parameters and design choices determine the actual algorithm of a Feistel cipher?
Total for Question 4: 3
5. AES
(a) 2 points What is the difference between Rijndael and AES?
(b) 1 point What is the purpose of the State array?
(c) 1 point Briefly describe the key expansion algorithm.
6. Given the plaintext 000102030405060708090A0B0C0D0E0F and the key 01010101010101010101010101010101.
Page 2 of 4
(a) 2 points Show the original contents of State, displayed as a 4 × 4 matrix.
(b) 2 points Show the value of State after initial AddRoundKey.
(c) 2 points Show the value of State after SubBytes.
(d) 2 points Show the value of State after ShiftRows.
(e) 2 points Show the value of State after MixColumns.
Total for Question 6: 10
7. Public Key Encryption
(a) 3 points What are three broad categories of applications of public-key cryptosystems?
(b) 3 points What requirements must a public-key cryptosystems fulfill to be a secure algorithm?
(c) 2 points What is a trap-door one-way function?
(d) 3 points Perform encryption using the RSA algorithm, as in Figure 9.5, for the following parameters:
c.
p = 7; q = 11, e = 17; M = 8
(e) 3 points Perform decryption using the RSA algorithm, as in Figure 9.5, for the following:
p = 17; q = 31, e = 7; C = 128
(f) 3 points Perform decryption using the RSA algorithm, as in Figure 9.5, for the following:
p = 11; q = 13, e = 11; C = 106
(g) 3 points In a public-key system using RSA, you intercept the ciphertext C = 10 sent to a user
whose public key is e = 5, n = 35. What is the plaintext M?
(h) 4 points In a RSA cryptosystem, the public key of Alice is e = 47, n = 4757. Find the private
key of Alice. Hint: First use trial-and-error to determine p and q; then use the extended Euclidean
algorithm to find the multiplication inverse of 47 modulo φ(n).
Total for Question 7: 24
8. Hash Functions
(a) 2 points What is the role of a compression function in a hash function?
Total for Question 8: 2
9. Message Authentication and Digital Signatures
(a) 2 points What two levels of functionality comprise a message authentication or digital signature
mechanism?
(b) 1 points When a combination of symmetric encryption and an error control code is used for
message authentication, in what order must the two functions be performed?
(c) 2 points What is the difference between a message authentication code and a one-way hash
function?
(d) 1 points Is it necessary to recover the secret key in order to attack a MAC algorithm?
(e) 2 points What requirements should a digital signature scheme satisfy?
Passive attacks
Release of message contents: An Eavesdropper can listen and read the shared data between two parties.
Traffic Analysis: The attackers or eavesdropper involves to analysis the packets which is are sent between sender and receiver. Attackers can sniff the passwords within packets.
Get solution
shopping Cart
Your Shopping Cart is empty
subject | solution code | Description | price |
---|
Now take our online assignment writing services in Australia.
payment methods
livewebtutors is the finest platform for all the assignment help for students. Here you can avail the optimum writing help under the guidance of renowned researchers and subject experts...
start learn© Livewebtutors. All Rights Reserved 2018