Ecosyste.ms: Awesome
An open API service indexing awesome lists of open source software.
https://github.com/cuhsat/practical
A one-time pad variant for easy manual application.
https://github.com/cuhsat/practical
algorithm cipher cryptography one-time-pad one-time-pad-cipher practical python strong
Last synced: 25 days ago
JSON representation
A one-time pad variant for easy manual application.
- Host: GitHub
- URL: https://github.com/cuhsat/practical
- Owner: cuhsat
- License: unlicense
- Created: 2015-03-23T12:39:18.000Z (almost 10 years ago)
- Default Branch: master
- Last Pushed: 2018-01-09T07:56:28.000Z (almost 7 years ago)
- Last Synced: 2023-02-27T22:33:12.462Z (almost 2 years ago)
- Topics: algorithm, cipher, cryptography, one-time-pad, one-time-pad-cipher, practical, python, strong
- Language: Python
- Homepage:
- Size: 24.4 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# The Practical Cipher 
A one-time pad variant for easy manual application. Based on a 6x6 conversion
table supporting alphanumeric symbols. Random key generation can be done with
one normal gambling dice (d6).
An implementation in Python is provided.
## Specification
### Conversion Table
The conversion table uses a 6x6 alphanumeric matrix. It is filled from left
to right and from top to bottom with the uppercase latin letters of the
alphabet from `A` to `Z` and than the numbers from `0` to `9`.
> Please note, the _x_ and _y_ indices start at zero.
The conversion table with the default symbol arrangement:
```
0 1 2 3 4 5
0 A B C D E F
1 G H I J K L
2 M N O P Q R
3 S T U V W X
4 Y Z 0 1 2 3
5 4 5 6 7 8 9
```
> The used symbols might be replaced with `meta` symbols e.g. like `not`,
> which might alter prior or following statements.
### Encryption
Encryption is done in six easy steps:
1. Convert the key and plain text symbol to its _x_ and _y_ positions
2. Add the keys _x_ position to the plain texts _x_ position
3. Add the keys _y_ position to the plain texts _y_ position
4. Divide the _x_ position by _6_ and use the remainder as the new _x_ position
5. Divide the _y_ position by _6_ and use the remainder as the new _y_ position
6. Convert the so calculated _x_ and _y_ positions to the cipher text symbol
Repeat with the next symbol if needed.
#### Example
```
H E L L O Plain text (symbols)
11 04 15 15 22 Plain text (positions)
X X X X X Key (symbols)
+ 35 35 35 35 35 Key (positions)
Y V 2 2 5 Cipher text (symbols)
= 40 33 44 44 51 Cipher text (positions)
```
### Decryption
Decryption is done in six easy steps:
1. Convert the key and cipher text symbol to its _x_ and _y_ positions
2. Substract the keys _x_ position from the cipher texts _x_ position
3. Substract the keys _y_ position from the cipher texts _y_ position
4. Divide the _x_ position by _6_ and use the remainder as the new _x_ position
5. Divide the _y_ position by _6_ and use the remainder as the new _y_ position
6. Convert the so calculated _x_ and _y_ positions to the plain text symbol
Repeat with the next symbol if needed.
#### Example
```
Y V 2 2 5 Cipher text (symbols)
40 33 44 44 51 Cipher text (positions)
X X X X X Key (symbols)
- 35 35 35 35 35 Key (positions)
H E L L O Plain text (symbols)
= 11 04 15 15 22 Plain text (positions)
```
### Key Generation
Key generation is done in three easy steps:
1. Throw a six-sided gambling dice, use the result minus _1_ as the _x_ position
2. Throw a six-sided gambling dice, use the result minus _1_ as the _y_ position
3. Convert the _x_ and _y_ positions to the key symbol
Repeat with the next symbol if needed.
> It is advised to separate the key into blocks of five symbols for better
> readability and therefor a lesser chance of encryption/decryption errors.
For more information on randomness, please see [1].
#### On Key Distribution
Key distribution should be done directly after the key generation. It is
advised to create the keys by hand. Write down the generated keys to two
pieces of paper or books. The pages can be marked with page numbers for
easier locating of the key blocks later.
> It is advised to not use a computer system or any other electronic device to
> generate or distribute the keys.
#### On Key Synchronization
In order for both peers to refer to the same key, the keys to use must be
synchronized between each message. The simplest way to do so is using a key
book and referring to the used key by the page number.
### Security Considerations
There are a few points to consider, to ensure maximal confidentiality:
* Every key *must* be kept secret
* Every key *must not* be used twice
* Every peer *must* destroy the key directly after usage
* Only two peers *should* have the same key
## Implementation
### Usage
```$ practical.py COMMAND [KEY TEXT...]```
Available commands:
* `-e, --encrypt`
* `-d, --decrypt`
* `-k, --key`
#### Example
```
$ practical.py --encrypt XXXXX HELLO
```
```
$ practical.py --decrypt XXXXX YV255
```
```
$ practical.py --key
```
### Exports
This Python script exports the `Practical` class.
#### Practical.encrypt(text, key)
Returns the given `text` encrypted with the given `key` as string.
#### Practical.decrypt(text, key)
Returns the given `text` decrypted with the given `key` as string.
#### Practical.key(size=5, cols=5, rows=15)
Returns a new random key of the given `size`, `cols` and `rows` as string.
#### Example
```python
from practical import Practical
practical = Practical()
print(practical.encrypt("HELLO", "XXXX"))
print(practical.decrypt("YV255", "XXXX"))
print(practical.key())
```
## License
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or distribute
this software, either in source code form or as a compiled binary, for any
purpose, commercial or non-commercial, and by any means.
----
[1] [Randomness for Crypto](https://www.cs.berkeley.edu/~daw/rnd/)