Old pencil and paper cryptosystems.

As you may have seen from my site, I have long been interested in old pencil and paper cryptosystems, even before getting hooked on computers. Over the years, I have re-implemented a few of them in various languages:

• Old BASIC on my Sinclair QL like ages ago
• Like 15 years ago in Ruby
• Then in Go when I learned the language in 2016
• And more recently in, what else, Rust

Cipher List

In order of complexity, here are the systems implemented:

• Caesar (yes, Julius Caesar himself), a simple substitution cipher
• Basic Transposition cipher, basic columnar one, mostly used as part of others because it is too simple
• A basic Polybius square cipher from ancient Greece
• Playfair cipher , created by Sir Charles Wheatstone but popularised by the Baron Playfair
• A more complex square cipher, using frequency analysis to shorten the ciphertext and complicate cryptanalysis, called the Straddling checkerboard
• The Wheatstone cipher machine, a mechanical device for encryption and decryption invented by the same Charles Wheatstone
• Chaocipher , a simple cipher machine invented by John Francis Byrne in 1918

and some more complex ones, using some above to add superencipherement like

• ADFGVX cipher , used by the German Army during WWI, finally broken in time by Georges Painvin in 1918
• The Nihilist Cipher used by the Russian Nihilist in the 1880s against the Tsar
• The VIC cipher , a more complex one used by Soviets during the Cold War
• The SIGABA Cipher Machine , created by the US Signal Intelligence Service during WWII, more complex than the German Enigma Machine .

and even this one:

• Solitaire , a card-based simple stream cipher invented by Bruce Schneier for Neal Stephenson’s book, The Cryptonomicon

Usage

It is fairly easy to use, just look into the examples/demo.rs file.

1    use old_crypto::{Block, ADFGVX};
2
3    let c = ADFGVX::new("CIPHER", "MACHINE");
4    let plaintext = "THISISANEXAMPLE".to_string();
5    
6    let mut ct = vec![]; 
7    let n = c.encrypt(&mut ct, plaintext.as_bytes())?;
8    let ciphertext = String::from_utf8(ct)?;
9    println!("{plaintext} => {ciphertext}"); 

The Go example is even simpler:

1    package main
2    
3    import (
4        "fmt"
5    
6        "github.com/keltia/cipher"
7        "github.com/keltia/cipher/adfgvx"
8    )
9    
10    func main() {
11        c, _ := adfgvx.New("CIPHER", "MACHINE")
12        plaintext := "THISISANEXAMPLE"
13        
14        dst := make([]byte, len(plaintext) * 2)
15        c.Encrypt(dst, []byte(plaintext))
16        fmt.Printf("%s => %s\n", plaintext, string(dst))
17    }

URLs

• Ruby version
• Go version
• Rust version