# Name: : : _____ Secret Codes Encryption is used by spies, secret

Name : _______________________________ Date : _______________ Period : _____ Secret Codes Encryption is used by spies, secret societies, and other organizations to transfer information without other people reading their messages. Secret codes can be created by a simple scheme of replacing letters with numbers. More complex codes replace letters with other letters. The code scheme is called a cipher and can be written as a list or table.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6

Use the cipher above to decode these messages. Question ::

23 8 1 20 4 9 4 20 8 5 26 5 18 15 19 1 25 20 15 20 8 5 5 9 7 8 20? ________________________________________________________________________________

14 9 3 5 2 5 12 20 _______________________________________________

Ciphers can be written in which letters are replaced with other letters, not numbers. A scheme is determined for replacement. Often, letters are shifted. For example, a letter could be replaced with the letter three down the alphabet.

A B C D E F G H I D E F G H I J K L M N O P Q R S T U V W X Y Z J K L M N O P Q R S T U V W X Y Z A B C

Using the cipher above , “ TWINKLE TWINKLE LITTLE STAR ” becomes “ WZLQOH WZLQOH OLWWOH VWDU “. The next line is “HOW I WONDER WHAT YOU ARE”

Use the cipher to write it in code!

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A letter to letter code can also be represented in a graph. Determine the cipher represented in the graph below.

A B C D E F G H I L M N O P Q R S T U V W X Y Z A B C D E F G H I J K L M N O P Q R S T U V W X Y Z J K

Use the code cipher above to code the message “ MATH IS FUN ” ________________________________________ Use the cipher to decode “ T SLGP L DPNCPE ” ________________________________________