Can you please give a solution for 2, 4 , 5,6,7 asap ?

CPE 645 Computer Network SecurityFall 2015Mid-term # 1Department of Electrical and Computer EngineeringThe University of Alabama in Huntsville1.(10 points) Consider the storage of data in encrypted form in a large database using AES. Onerecord has a size of 16 bytes. Assume that the records are not related to one another. Whichmode would be best suited and why?2.(10 points) You have received the following cipher text which was encoded with a simple shiftcipher:xultpaajcxitltlxaarpjhtiwtgxktghidhipxciwtvgtpilpitghlxiwiwtxgqadds.Perform an attack against the cipher based on a letter frequency count: How many letters do youhave to identify through a frequency count to recover the key? What is the clear text?3.(10 points) Find all integers n between 0 ≤ n < m that are relatively prime to m for m = 4, 5, 9, 26.We denote the number of integers n which fulfill the condition by φ (m), e.g. φ (3) = 2. Thisfunction is called “Euler’s totient function”. What is φ (m) for m = 4, 5, 9, 26?4.(15 points) A commercial file encryption program from the early 1990s used standard DES with56 key bits. In those days, performing an exhaustive key search was considerably harder thannowadays, and thus the key length was sufficient for some applications. Unfortunately, theimplementation of the key generation was flawed, which we are going to analyze. Assume thatyou can test 106 keys per second on a conventional PC.The key is generated from a password consisting of 8 characters. The key is a simple concatenationof the 8 ASCII characters, yielding 64 = 8 x 8 key bits. With the permutation PC−1 in the keyschedule, the least significant bit (LSB) of each 8-bit character is ignored, yielding 56 key bits.1. What is the size of the key space if all 8 characters are randomly chosen 8-bit ASCII characters?How long does an average key search take with a single PC?2. How many key bits are used, if the 8 characters are randomly chosen 7-bit ASCII characters (i.e.,the most significant bit is always zero)? How long does an average key search take with a singlePC?5.(10 points) Assume we perform a known-plaintext attack against DES with one pair of plaintextand cipher text. How many keys do we have to test in a worst-case scenario if we apply anexhaustive key search in a straightforward way? How many on average?6.(15 points) For the following, we assume AES with 192-bit key length. Furthermore, let us assumean ASIC (Application Specific Integrated Circuit) which can check 3 x 107keys per second. If we use

• 1496043357-CPE645_FA15_Mid-term1.pdf

ComputerScienceExpert

(11)

Status NEW Posted 29 May 2017 07:05 AM My Price 9.00

-----------

Attachments

file 1496043358-Solutions file 2.docx preview (51 words )

H-----------ell-----------o S-----------ir/-----------Mad-----------am ----------- Th-----------ank----------- yo-----------u f-----------or -----------you-----------r i-----------nte-----------res-----------t a-----------nd -----------buy-----------ing----------- my----------- po-----------ste-----------d s-----------olu-----------tio-----------n. -----------Ple-----------ase----------- pi-----------ng -----------me -----------on -----------cha-----------t I----------- am----------- on-----------lin-----------e o-----------r i-----------nbo-----------x m-----------e a----------- me-----------ssa-----------ge -----------I w-----------ill----------- be----------- qu-----------ick-----------ly -----------onl-----------ine----------- an-----------d g-----------ive----------- yo-----------u e-----------xac-----------t f-----------ile----------- an-----------d t-----------he -----------sam-----------e f-----------ile----------- is----------- al-----------so -----------sen-----------t t-----------o y-----------our----------- em-----------ail----------- th-----------at -----------is -----------reg-----------ist-----------ere-----------d o-----------n -----------THI-----------S W-----------EBS-----------ITE-----------. ----------- Th-----------ank----------- yo-----------u -----------

Not Rated(0)

• Buy Answer