Retro Ciphers

Retro Ciphers is implementations of classical and historical ciphers. It is intended for educational purposes, cryptography enthusiasts, or anyone interested in the history of hidden messages.

This package encompasses both Monoalphabetic and Polyalphabetic substitution ciphers,to include modern interpretations as well as strict, historically accurate 15th-century variants.

Installation

You can easily install retro-ciphers via pip:

pip install retro-ciphers

(Requires Python 3.12 or higher)

Features

retro-ciphers provides clean, object-oriented API access to the following historical ciphers:

Monoalphabetic Ciphers

• Atbash: The classic Hebrew reversal cipher.
• Caesar / Shift / ROT13: Classical shift ciphers with custom shift lengths.
• Mixed Alphabet: Key-based shift mechanisms mapping the standard alphabet.
• Simple Substitution: Create completely custom scrambled mappings.
• Baconian Cipher: Francis Bacon's steganographic, binary-like cipher (supports both classic 24-letter and modern 26-letter alphabets).
• Polybius Square: The classical ancient Greek fractionating cipher (coordinates).

Polyalphabetic Ciphers

• Alberti Cipher: The first polyalphabetic cipher! Supports both standard English 26-character modern modes AND the historically accurate 1467 Latin 24/24 Character Disks implementation seamlessly!
• Trithemius Cipher: Johannes Trithemius's tabula recta system.
• Vigenère Cipher: The famous, unbroken mathematical improvement using table offsets.
• Beaufort Cipher: A variant of Vigenère using a reversed tabula recta mechanism.
• Autokey Cipher: An extension where the plaintext itself becomes part of the key.

Quick Start

The API is simple: initialize your chosen cipher, then use .cipher() to encrypt and .decipher() to decrypt text.

Monoalphabetic Examples

from retro_ciphers.mono import Caesar, Atbash, Baconian

# Caesar Cipher
caesar = Caesar() # Default shift of 3
encrypted = caesar.cipher("Hello World!")
# >>> "Khoor Zruog!"

# Atbash Cipher
atbash = Atbash()
print(atbash.cipher("Classical Cryptography"))
# >>> "Xozhhzxzo Xibkgltizksb"

# Baconian Cipher
bacon = Baconian(modern_implementation=True)
print(bacon.cipher("Hide"))
# >>> "AABBBABAAAAABABAABAA"

Polyalphabetic Examples

from retro_ciphers.poly import Vigenere, Alberti

# Vigenère Cipher
vigenere = Vigenere("LEMON")
encrypted = vigenere.cipher("ATTACK AT DAWN")
print(encrypted)
# >>> "LXFOPV EF RNHR"

decrypted = vigenere.decipher(encrypted)
print(decrypted)
# >>> "ATTACK AT DAWN"

# Alberti Cipher (Historical 1467 Mode)
# Uses the original Latin outer ("ABCDEFGILMNOPQRSTVXZ1234") and inner mappings
alberti = Alberti(key="a", modern_implementation=False)
secret = alberti.cipher("ABCDEFGHI")
print(secret)

Extra arguments

• omit_non_alpha: Available in the cipher() methods across ciphers (such as Alberti and Autokey). Accepts a boolean value (default: False). If True, it removes special symbols such as punctuation from the ciphertext. If False, it safely passes them through so they are kept intact.
• Alberti(key, frequency=50, modern_implementation=True):
  • modern_implementation: By default (True), the cipher uses the standard modern English A-Z alphabet. If you pass False, it enforces the historically accurate 1467 24-character Latin disks.
  • frequency: By default (50), the Alberti cipher automatically changes its mapping disk (indicating via a new outer key) every 50 characters to improve security against cryptanalysis. You can increase or decrease this rate.
• Baconian(modern_implementation=True): By default (True), uses the full 26-letter alphabet. If False, it mimics Bacon's original 24-letter alphabet where 'I' & 'J' and 'U' & 'V' map to the same sequences.

License

This project is licensed under the MIT License - see the LICENSE file for details.