YALE UNIVERSITY
DEPARTMENT OF COMPUTER SCIENCE
CPSC 467: Cryptography and Computer Security | Handout #3 | |
Professor M. J. Fischer | September 6, 2017 | |
Homework Assignment 2
Due by 11:59 pm on Wednesday, September 13, 2017
Please submit your solutions in electronic form as you did for Homework Assignment 1. (See handout 2.)
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Happy Hacker read about the affine cipher. He liked that it had a bigger key space than the Caesar cipher, but he thought it should be bigger still, so he invented the double affine cipher. Here’s how it works.
Consider the Playfair cipher with passphrase
WE MUST STATE RELATIONSHIPS, NOT PROCEDURES - GRACE HOPPER
RZ TI RY TP EA IC TR GV
Read chapter 1 of the Paar and Pelzl textbook, Understanding Cryptography. Then solve problem 1.2 on book page 24. (The PDF page number may differ.) Be sure to explain your answers.
You are free to make any use of computers that you wish for this problem, using any programming language or tools that you are comfortable with. As with any problem set, show your work. That means if you wrote a program to help you solve the problem, then submit the code as well as your answers. The code will not be graded, but in case your answer differs from the correct one, it will help with the grading. If you make use of somebody else’s code, then be sure to properly acknowledge the source of that code.