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| Chapter 7: Factoring
Numbers in the Real World |
Tales of the Crypt
Security on the Internet is always a concern. Proper encoding is necessary to keep important personal information such as credit card numbers, social security numbers, etc. out of the hands of unauthorized people.
There are many types of encoding. The simplest type is called Caesar
Code, where each letter is replaced by another letter x letters away. The
following table shows a Caesar Code with x=5.
| Caesar Code |
| a b c d e
f g h i j k
l m
f g h i j k l m n o p q r |
| n o p q r
s t u v w x
y z
s t u v w x y z a b c d e |
Encode the following expression: Math Rules
Decode the following sentence: xqtuj tk f qnsj nx hmfslj ns d bnym wjxujhy yt hmfslj ns c.
Show a friend this encryption code and trade encoded messages using Caesar Code with an x value other than 5.
What other schemes could you use to encrypt a message?