Printable One Time Pad generatator written in BASH.
Using your system's random number generator (which should be a hardware, true random number generator) or a source file, padgen can create simple printable one time pads.
Most of the output is similar to Numbers without the need to install Windows or Wine. Just need BASH and RNG source.
padgen can generate checkboard layouts both in a larger format:
-----------------------------------------------------
| CODE A E I N O T | STANDARD |
| 0 1 2 3 4 5 6 | TABLE No. 1 |
|---------------------------------------------------|
| B C D F G H J K L M |
| 70 71 72 73 74 75 76 77 78 79 |
|---------------------------------------------------|
| P Q R S U V W X Y Z |
| 80 81 82 83 84 85 86 87 88 89 |
|---------------------------------------------------|
| FIG . : ' () + - = REQ SPC |
| 90 91 92 93 94 95 96 97 98 99 |
-----------------------------------------------------
+ +
| LETTERS | | NUMBER
| 7 8 | 9 | NN
-+-------------------------
0|CODE B P |FIG| 0
1| A C Q | . | 1
2| E D R | : | 2
3| I F S | ' | 3
4| N G U |() | 4
5| O H V | + | 5
6| T J W | - | 6
7| K X | = | 7
8| L Y |REQ| 8
9| M Z |SPC| 9
+ +
Pads generated with page numbers, both in and out copies in a run. Cut down the middle and give the IN to the sender and OUT to the receiver.
usage: padgen.sh [OPTIONS]
-h, --help Display this info
-v, --version Display version number
Checkerboard
-cb TYPE Print Checkerboard
Types:
Basic Basic board with no condensed letters.
Two numbers per character, Code, Space
and 12 punctuation.
StdTbl Standard Table No. 1. 6 condensed characters
7 punctuation. Numbers enabled using FIG and
questions enabled using REQ.
CT37 CT-37
CT46 CT-46
CT55 CT-55
Pad
-p, --pad Print One Time Pads, additional options
-f FILE Source of random data. Stdin set with "-"
and defaults to /dev/urandom.
-sn NUM Serial Number. This define the id for the
entire pad. Default 0.
-idx NUM Index. This defines the id of an individual
page. Each new page increments. Default 0
-cnt NUM Count. This defines the number of pages to
include in the pad. Default 1.
-t Disable title card
-cb TYPE Insert a small Checkerboard into each set of
cards.
Manual Pad
-m, --manual Print Manual One Time Pads, additional options
-t Disable title card
-cb TYPE Insert a Checkerboard into the set of cards
-
Print Pad, cut in half. IN is used to encrypt and OUT is used to decrypt.
-
Using an agreed upon checkerboard, convert your Clear text to a sequence of numbers.
-
In groups of 5 characters, line up Clear Text and Pad.
Clear: 12345 67890 Pad: 01928 49285 -
To encrypt subtract Pad from Clear Text without borrowing (5 - 9 = 6, not 15 - 9)
Clear: 12345 67890 Pad: - 01928 49285 Cipher: 11427 28515 -
To decrypt add Pad to Cipher without carring (6 + 9 = 5, not 15)
Cipher: 11427 28515 Pad: + 01928 49285 Clear: 12345 67890 -
First 5 digits of Cipher text should be the Page Number of the pad used. Be sure to destroy it after use.
00001 11427 28515 Page# Cipher.....
The checkerboard allows you to encode your message into a sequence of numbers, which makes encryption much easier to do by hand. Both sides must agree to which board to use, each letter/symbol converts to a single or double digit number.
-----------------------------------------------------
| CODE A E I N O T | STANDARD |
| 0 1 2 3 4 5 6 | TABLE No. 1 |
|---------------------------------------------------|
| B C D F G H J K L M |
| 70 71 72 73 74 75 76 77 78 79 |
|---------------------------------------------------|
| P Q R S U V W X Y Z |
| 80 81 82 83 84 85 86 87 88 89 |
|---------------------------------------------------|
| FIG . : ' () + - = REQ SPC |
| 90 91 92 93 94 95 96 97 98 99 |
-----------------------------------------------------
As an example, the top row of letters are represented by single digit numbers.
The word DAWN converts to 721864
- A = 1
- T = 6
- Space = 99
- D = 72
- A = 1
- W = 86
- N = 4
Numbers are written by first using the FIG command, and each digit is printed
in triplicate and ending with FIG. 2017 is converted to
90 222 000 111 777 90. Some boards have L/F which operates the same as FIG.
CODE is used when both parties have a code book of common words. Lets say
your code book has the word ABORT with the value 123. Encoding ABORT NOW
would be 0 123 99 4 5 86
Some common codes for on boards are SPC (space), REQ (request), RPT (repeat)
Be sure to use a good RNG source. For example a Raspberry Pi's Hardware RNG or a USB Hardware RNG.
Make sure to keep all outputs from this script either in files on a tempfs
partition or pipe all output directly to your printer so no copy ever is
written to disk.
./padgen.sh -p | lp
NEVER reuse a pad. Print one copy, cut it and distribute. When you use a page to encrypt, destroy it once you are done encrypting. If you do not use the entire page...still destroy it.
Always encrypt with the IN pad and always decrypt with the OUT pad. For two
people to communicate this means you need to print out two different pads.
Person A's IN pad matches person B's OUT pad. This way if both are sending
messages there should be no accidental reuse of any pad since each one only has
an IN or an OUT from a given pad, but not both.
If you don't feel comfortable using computer generated random numbers, you can
use he -m flag to generate a blank pad and use some 10 sided dice to generate
your pad.