Substitution

The Dorabella Cipher is a mysterious and undeciphered cipher created by Edward Elgar, the famous English composer, in 1897. The cipher consists of 87 characters arranged in lines, using 24 unique symbols resembling semicircles rotated at different angles. Each symbol likely represents a letter, digraph, or some phonetic element, but the exact system remains unknown.

The Digraph Cipher is a classical encryption technique that encodes plaintext two letters at a time — in units called digraphs. By encrypting pairs of letters instead of individual letters, it hides single-letter frequency patterns, making simple frequency analysis ineffective. This is why it is stronger than single-letter substitution ciphers like the Simple Substitution Cipher.

A Dice Cipher, also known as a Dice Cryptography or a Book Cipher, is a cryptographic technique that uses dice as a randomization tool to generate a series of numbers that correspond to words or characters in a pre-selected reference book. It is a form of polyalphabetic substitution cipher.

Here's a general overview of how a Dice Cipher works:

The Combination Cipher is not a single fixed algorithm but a method that deliberately combines two or more classical ciphers into a layered encryption process. By applying multiple techniques in sequence — typically a substitution followed by a transposition — the resulting ciphertext becomes significantly harder to analyze than either method alone.

The Chaocipher is a sophisticated and historically intriguing cipher invented by John F. Byrne in 1918. Unlike traditional substitution ciphers, the Chaocipher uses two rotating disks—one for the plaintext alphabet and one for the ciphertext alphabet—both of which are permuted after each letter is encrypted. This dynamic reordering ensures that the same plaintext letter never encrypts to the same ciphertext letter twice in a row, creating a highly irregular polyalphabetic system.

The Caesar Cipher is a classical substitution cipher named after Julius Caesar, who reportedly used it to encrypt private correspondence. It shifts each letter in the plaintext by a fixed number of positions down the alphabet. This simplicity makes it easy to understand and implement, but also vulnerable to frequency analysis and brute-force attacks due to its limited keyspace.

The Book Cipher is a classical encryption method in which numbers in the ciphertext refer to positions within an agreed-upon text, known as the key book. Instead of substituting letters directly, the cipher uses an external document as the lookup table. Without the exact same book, edition, and formatting, the ciphertext is effectively meaningless.

Book Cipher: Encoding

By default, spaces and punctuation are excluded when counting positions. Letters are indexed sequentially as a continuous stream of characters.

Using the key text:

The Bifid Cipher is a classical polygraphic cipher developed by Félix Delastelle in the early 20th century. It combines a Polybius (Square) Cipher with transposition to create a system that diffuses plaintext letters across multiple ciphertext symbols.

The Beaufort Cipher is a polyalphabetic substitution cipher closely related to the Vigenère Cipher. Invented by Sir Francis Beaufort in the 19th century, it uses a reversed encryption mechanism compared to Vigenère: instead of adding key values to plaintext letters, the plaintext letters are subtracted from the key letters modulo 26. This results in a symmetric system where encryption and decryption processes are identical, simplifying usage while retaining polyalphabetic complexity.

The Beale Cipher is a set of three ciphertexts that allegedly reveal the location of a hidden treasure buried in the United States in the early 19th century. Only one of the three ciphers, commonly referred to as Beale Cipher #2, has been solved, revealing the treasure’s contents using a book cipher method.