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Assignment No. 02
Semester: Spring 2018
Total Marks: 20
Due Date: 04/06/2018
Please read the following instructions carefully before submitting assignment:
§ You will submit your assignment before or on due date on VU-LMS.
§ Assignment should be completed by your own efforts it should not be copied from internet, handouts or books.
§ You should submit your .doc File via assignment interface at VU-LMS.
§ Assignment sent via Email will not be replied and accepted in any case.
§ If the submitted assignment does not open or file is corrupt, it will not be marked.
§ You will submit solution only in document (.doc or .docx) File.
To build the proper understanding of following topics:
a) Hash Function
b) Encryption Algorithm
For any query about the assignment, contact at firstname.lastname@example.org
Question : Marks 20
Part a) 10 marks
Suppose a hacker is trying to attack a secure hash function. Calculate the following to know the level of effort required by hacker if the hash code is of length ‘16’:
· Pre-image resistant
· Second pre-image resistant
· Collision resistant
Part b) 10 marks
Consider a very simple symmetric block encryption algorithm in which 32-bits blocks of plaintext are encrypted using a 64-bit key. Encryption is defined as
C = (P ⊕ K0) + K1
Where C = ciphertext,
K secret = key,
K0 = leftmost 64 bits of K,
K1 = rightmost 64 bits of K,
⊕ = bitwise exclusive OR,
+ and is addition mod 264.
i. Show the decryption equation. That is, show the equation for P as a function of C,
K0, and K1.
ii. Suppose and adversary has access to two sets of plaintexts and their corresponding
ciphertexts and wishes to determine K.We have the two equations: C (P K0) K1; C' (P' K0) K1
First, derive an equation in one unknown (e.g., K0). Is it possible to proceed further to solve for K0?
Came Bhai buri khabar e sunana