One Time Pad Coding Tool

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$8.95 + tax & shipping
Get one for each member of your group!

Secure Communication for your Group

We looked at the methods promoted online for using One Time Pad encryption, but for the average Joe, it’s way too complicated. Most people have problems balancing their checkbooks, even more so performing modulo arithmetic!

So we created our One Time Pad Coding Tool that helps you produce alphanumeric cipher text. This tool is a set of two USA-made waterproof plastic cards that easily stow into a pack or pocket.

To make your pad of random numbers, use our generator here.

Encryption

Encrypting messages as cipher text is easy. On the tool, plain text is green on one card, and the cipher text is red on the other. As an example, let’s say that the next page of your pad reads

    8, 11, 42, 13, 39, 34, 6, 25, 23, 46, 19, 43, 36, 35

To encode the sample message “BACK SOON”:

    1. Select the next number from your pad (8, from the pad above).
    2. Find line number (8) on the red card and align the green text on the other card.
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    3. Find the next plain text letter of the message, ‘B’, on the green line.
    4. Read off the red cipher text letter beside it, in this case ‘:’.
    5. Repeat from step 1 to encrypt the other letters of the message.
    Plain text B A C K sp S O O N
    Pad Number 8 11 42 13 39 34 6 25 23
    Cipher text : $ K ) B 8 I $ sp

    (You don’t have to write all this stuff down! Using the coding tool eliminates all this bookkeeping. Just record or send the cipher text as it is created.)

Decryption

To decrypt the message, work backwards:

    1. Select the next number from your pad (8, from the pad above).
    2. Find line number (8) on the red card and align the green text on the other card.
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    3. Find the cipher text letter on the red line (‘:’).
    4. Read off the green plain text letter, ‘B’.
    5. Repeat from step 1 to decrypt the other letters of the message.

With a little practice, you should be able to encrypt and decrypt messages without writing down intermediate information. Our tool makes numeric one time pad encoding much easier than computing with pencil and paper.

Security

As you use each section of your pad, tear it off and destroy it. It’s easiest to use each page from the bottom up, tearing off each used section immediately after use. Do not ever reuse a pad section.

padTo help the receiving person know what section of the pad you are using, transmit the first two numbers from the pad section. Transmit these in the clear as they are just random numbers having no meaning to anyone without the pad. Then use pad numbers after the first two you transmitted.

You can even assign different pads to different people or groups, as your organizational needs demand.

Authentication

Encryption is good, but what if someone captures your pad and sends bogus messages to your friends? They would have no way to know it’s not you sending the messages. To avoid this problem, be sure you sign your messages with an authentication code of your choosing. There are several ways to do this:

  • Give each person his or her own authentication code
  • Use one authentication code for the entire group
  • Use an authentication code that changes with each message, like the time of day or a message number

If no one ever writes down the authentication code, then people capturing your written communiques would have no idea it was even needed, and the messages they sent would be ignored, and would be a warning that something is wrong.

A sample plain text message might be, “MEETING AT 18:00 HRS. BR549”. (The text “BR549” is the authentication code.)

Abbreviations and Phonetics

While the One Time Pad tool is easy to use, it still takes time to encode each character in the message. Abbreviations speed up message composition and decoding. (Many words can be abbreviated just by deleting the vowels.) Here are some abbreviations for common English words:

abt  about      bcse  because     com  come
cld  could      dy    day         evn  even
fnd  find       frst  first       fr   for
frm  from       gv    give        hv   have 
hr   her        hre   here        hm   him 
hs   hs         hw    how         nto  into 
jst  just       knw   know        lke  like
lk   look       mke   make        mny  many
mre  more       nw    now         nt   not
nly  only       oth   other       ppl  people 
sy   say        sh    she         som  some 
tak  take       tel   tell        thn  then
tht  that       thr   there       thm  them
ths  this       thy   they        thng thing
thnk think      tim   time        vry  very 
wnt  want       wll   well        wht  what
whn  when       whch  which       wil  will
wth  with       wld   would       yr   year
u    you        ur    your

When transmitting encrypted messages by voice, it helps to use the phonetic alphabet. Here’s a phonetic alphabet for the non-numeric characters used by the One Time Pad tool:

A Alfa      B Bravo     C Charlie     D Delta      E Echo 
F Foxtrot   G Golf      H Hotel       I India      J Juliett 
K Kilo      L Lima      M Mike        N November   O Oscar 
P Papa      Q Quebec    R Romeo       S Sierra     T Tango 
U Uniform   V Victor    W Whiskey     X Xray       Y Yankee 
Z Zulu      ! Bang      = Equal       - Dash       $ Dollar 
_ Space     . Period    , Comma       : Colon      ? Question 
/ Slash     ( Open      ) Close       " Quote      # Pound 

Print these aids and keep them with your pad sheets. These abbreviations are not confidential information.

Purchase the Coding Tool

The One Time Pad Coding Tool is available for purchase now. It is made in the USA, waterproof, 2.5 x 4.1 inches, and will fit in your pocket or pack for field use. Instructions for encryption and decryption are printed on one of the cards, as well as on this page. Get one for each member of your team. The only additional thing you need is the pad of numbers, which you can generate here for free!

Purchase the coding tool for $8.95 plus tax and shipping through our Paypal cart. This product is available in the US and Canada only. Get one for each member of your group!