First-Exam2-20-07 - First Examination CIS 4363 February 20,...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
First Examination CIS 4363 February 20, 2007 Name____________________________________________________________ 1. In this problem you will use a modified RC4 cipher. The text is encrypted at half a byte, 4 bits, at a time. Let’s call half a byte, 4 bits, as a unit. Vector S will be 16-unit long, from S[0] to S[15]. Each S[i] will have 4 bits, containing a number from 0 to 15. K will have a length equal or less then 16 units. Find the cipher text using the given K and plaintext. Assume that K is given in hex as xE3A. (i) Provide the contents of T after initialization. (2 points) (ii) Compute the contents of S after two iterations through the initial permutations of S. (4 points) (iii) Assume that the results obtained in (ii) are used in stream generation. What is the cipher text generated for the plaintext given in hex as xD5A. (9 points) 2. In this problem you will use a modified ECB cipher. Instead of encrypting 64 bits at a time, encrypt a fixed length of characters at a time using Hill cipher. Find the cipher text using the given Hill cipher key and plaintext. Hint: Convert each character to a number between 0 and 25, as in Hill cipher.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 2

First-Exam2-20-07 - First Examination CIS 4363 February 20,...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online