Exam1ReviewQs

# Exam1ReviewQs - question and the following set of letters:...

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

CIS 3362 Exam #1 Review Contest Questions 1) Encrypt "HAVEANICEDAY using the Keyword cipher with the keyword "JUICE", starting at A. Here is the key: Plain: ABCDEFGHIJKLMNOPQRSTUVWXYZ Cipher: JUICEABDFGHKLMNOPQRSTVWXYZ Answer: DJVEJMFIECJY 2) Find the corresponding decryption function for the affine encryption function f(x)=(5x+6)%26 x = (5f -1 (x) + 6) % 26 5f -1 (x) = (x – 6) % 26 21(5f -1 (x)) = 21(x – 6) % 26 f -1 (x) = (21x – 126) % 26 f -1 (x) = (21x + 4) %26 3) Encrypt "CRYPTOGRAPHY" using the multiliteral cipher with the keyword "UIJEC". Here's the encryption grid: U I J E C U A B C D E I F G H I/J K J L M N O P E Q R S T U C V W X Y Z Answer: UJEICEJCEEJEIIEIUUJCIJCE 4) Encrypt "KNIGHTS" using the Vigenere cipher and the keyword "UCF" Plain: KNIGHTS Key: UCFUCFU ------- Answer:EPNAJYM

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

View Full Document
5) What is the index of coincidence of the following set of letters: 2 As, 8 Bs, 4 Cs, and 6Ds? IC = 19 5 380 100 380 30 12 56 2 19 20 5 6 3 4 7 8 1 2 = = + + + = + + + x x x x x 6) What is the mutual index of coincidence between the set of letters in the previous
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: question and the following set of letters: 6 As, 7 Bs, 3 Cs, and 4 Ds? MIC = 50 13 400 104 400 24 12 56 12 20 20 4 6 3 4 7 8 6 2 = = + + + = + + + x x x x x 7) Find 23-1 mod 73. 73 = 3x23 + 4 , so 4 = 73 3x23 23 = 5x4 + 3, so 3 = 23 5x4 4 = 1x3 + 1, so 1 = 4 3. Now substitute for 3: 1 = 4 (23 5x4), so 1 = 6x4 23. Now substitute for 4: 1 = 6x(73 3x23) 23 1 = 6x73 19x23 Now, consider this equation mod 73: 1 = -19x23 (mod 73) Thus, our desired inverse is -19, which maps to 73 19 = 54. 8) Encrypt &quot;MINNESOTA&quot; with the Playfair cipher with the keyword &quot;KNIGHTS&quot;. Use the dummy letter 'X', if necessary. Since we have the double N lining up, we do have to use the dummy letter, so we end up encrypting &quot;MI NX NE SO TA&quot; Here's the playfair encryption grid: K N I/J G H T S A B C D E F L M O P Q R U V W X Y Z Answer: FHIWSPTPSB...
View Full Document

## This note was uploaded on 07/13/2011 for the course CIS 3362 taught by Professor Staff during the Fall '08 term at University of Central Florida.

### Page1 / 2

Exam1ReviewQs - question and the following set of letters:...

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

View Full Document
Ask a homework question - tutors are online