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You're reading fromThe Modern C# Challenge

Product type Book
Published in Oct 2018
Publisher Packt
ISBN-13 9781789535426
Pages 362 pages
Edition 1st Edition
Languages
Concepts
Author (1):
Rod Stephens

Title Page
Dedication
Packt Upsell
Contributors
Preface
1. Mathematics 2. Geometry 3. Dates and Times 4. Randomization 5. Strings 6. Files and Directories 7. Advanced C# and .NET Features 8. Simulations 9. Cryptography 1. Other Books You May Enjoy Index

Problems

Use the following problems to test your skills at building cryptographic programs. Give each problem a try before you turn to the example solutions for help.

91. Caesar cipher

In a Caesar cipher, also called a Caesar shift, Caesar substitution cipher, or shift cipher, you shift the values of the letters in the message by some fixed amount. In the original Caesar cipher, Julius Caesar reportedly used a shift of three to send secret messages to his commanders, so each letter was replaced by the letter that comes three positions later in the alphabet. The letter A was encrypted as D, B was encrypted as E, and so forth. Letters at the end of the alphabet wrap around to the beginning so, for example, X becomes A, Y becomes B, and Z becomes C. In this example, the shift value, 3, was the cipher's key.

Write a program that uses a Caesar cipher to encrypt and decrypt messages. Let the user enter some text and a shift and then click a button to encrypt the message. Let the user then enter a...

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