birthday party code book

8/8/2019 Birthday Party Code Book

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CodeBook


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Contents

Introduction ...........................................................................................................................3

Invisible ink .............................................................................................................................4

Morse code .............................................................................................................................5

Encoding Morse code .........................................................................................................6

Transposition cyphers ........................................................................................................7

Scytale ......................................................................................................................................8

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Introduction

So, youve got some codes to crack, and you want to know how to get

started? Youve come to the right place. This book will help you

gure outwhat to do in any puzzling situation. The main things to keep in mind are

stay calm, and I can gure this out.

The birthday invitation code is a simple

transposition cypher. Heres the key for

that code:

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Invisible ink

If you have a blank piece of paper that you believe has a message written

on it in invisible ink, youre halfway there. Most people would just throw ablank sheet of paper away, or use it for something else, or recycle it, or

turn it into a paper airplane. You secret agents know better though, dont

you?

If you have an invisible ink pen & developer, that might be exactly what

you need to read the message, but Be Careful! The ink & developer can be

reversed, and if you scribble the wrong one all over your paper, youll be

covering up the secret message! Try small corners or careful patterns to

determine if an invisible ink has been used on the paper.

Another form of invisible ink is lemon juice. The way you make these

messages appear is with a candle. But once again: Be Careful! If the paper

catches re, not only could you hurt yourself (or worse), but youll also

lose the secret in the process.

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Encoding Morse code

The tree is inconvenient if you want to send a message in Morse code. To

do that, use this 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 --..

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Transposition cyphers

A transposition cypher is where each letter in a word is replaced with

another symbol/letter/or number.Transposition cyphers are the basis of modern cryptography. The

simplest transposition cypher is the obvious A -> 1, B -> 2, C -> 3, and so

on. This code would always be easy to break, even if you scrambled up

which numbers went with which letters. Why? Because English text (and

most other languages) leaves ngerprints - some letters occur very

frequently (like a and e), and others are more rare (q and z), and

some words are very common (like the), so if you have enough text to

decode, these rules can help you get most of the way there. And even if

you dont have all the letters gured out, you can usually still read the

message. Do y*u kno* wh*t I me*n?

Did you know there is an unbreakable code? It relies on both sender and

receiver having a copies of a one time pad. The one time pad has a

sequence of numbers written on it. The numbers are random numbers,

like the result of rolling dice, or something like that. To encode a message

with a one time pad, you take your simple encoded message (A->1, B-

>2, ...) and add each number to the corresponding number in the one

time pad, and write down the sum. To decode it, you subtract the

number in the one time pad from the corresponding number in the

message. Its tedious, and it uses up a lot of numbers in the one time pad,

but as long as you dont reuse the one time pad, it cant be broken.

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Scytale

If you have a ribbon or thin sheet of paper with letters arranged vertically,

they may hold a message encoded with a scytale.A scytale (rhymes with Italy) is an ancient method of easily producing

and decoding coded messages. It is not a transposition cypher, because

each letter in the cleartext appears in the cyphertext, but the scytale

makes it dicult to read by scrambling the letters.

You encode a message with a scytale by wrapping a ribbon (or in olden

times, thin leather) around a sta, stick, or dowel of a specic diameter.

Once the ribbon is wrapped around, you write the message so that each

letter ts on one ribbon-width. It works best if you ll the ribbon with text,

because if you dont, the empty parts of the ribbon will help the bad

guys crack your code.

To decode the message, the recipient wraps the ribbon on a staof

exactly the same diameter and reads the message o. If a bad guy

intercepts the message, its very hard to gure out what it says.

If youre trying to decode a scytale, carefully go

through each dowel and also experiment with

which end of the ribbon to wrap rst, and in

which direction. You might have to try many

experiments before the message becomes clear!

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