Monoalphabetic

The Vatsyayana Cipher is a classical monoalphabetic substitution cipher that uses a keyword to generate a fixed substitution alphabet. It is structurally similar to other keyword-based substitution systems, but often emphasizes preserved spacing and case sensitivity, making it suitable for mixed-format plaintext input.

The cipher derives its name from historical cryptographic naming conventions associated with early substitution systems, and operates by constructing a deterministic mapping between plaintext and ciphertext letters using a keyword-generated alphabet.

The Patristocrat Cipher is a classic monoalphabetic substitution cipher where all spaces, punctuation, and formatting are removed before encryption. This produces a continuous string of letters, making frequency analysis slightly more challenging.

Patristocrat Cipher: Encoding

To encode with the Patristocrat Cipher using a keyword:

The Monoalphabetic Substitution Cipher is one of the simplest and most fundamental encryption techniques. It works by replacing each letter in the plaintext with a corresponding letter from a fixed substitution alphabet. Unlike polyalphabetic ciphers, the mapping remains constant throughout the entire message, meaning each plaintext letter always maps to the same ciphertext letter.

The Gold-Bug Cipher is a substitution cipher made famous by Edgar Allan Poe in his short story The Gold-Bug. Unlike standard alphabetic ciphers, this system replaces letters with a mixture of symbols, numbers, and punctuation marks, creating a visually distinctive ciphertext. The cipher is monoalphabetic, meaning each plaintext letter always maps to the same symbol, but its unusual character set makes it appear more complex than it actually is.

The Albam Cipher is a classical substitution cipher dating back to the early modern period. It is a simple monoalphabetic cipher in which each letter of the plaintext is replaced by the letter 13 positions ahead in a specialized rearranged alphabet. Unlike the standard Caesar Cipher, which shifts letters uniformly in the standard A–Z order, the Albam Cipher uses a fixed substitution mapping based on two halves of the alphabet: the first half (A–M) is paired with the second half (N–Z), and vice versa.

The Patristic Cipher is a letter-substitution format where the plaintext is first encrypted using a keyword-based substitution (like a keyed alphabet) and then formatted into uniform blocks (commonly 5 letters each). Spaces, punctuation, and other non-letter characters are removed so that the ciphertext appears as a continuous stream of letters, hiding word boundaries.

The Keyed Caesar Cipher is a variation of the classic Caesar Cipher that incorporates a keyword to reorder the alphabet before applying the traditional shift. By first creating a keyed alphabet, the cipher avoids the predictable sequential order of letters, making frequency analysis slightly more challenging while still maintaining the simple shift mechanism of the original Caesar system.

The Kama-Sutra Cipher is a classical substitution cipher that encodes letters in pairs, based on a fixed alphabetic mapping. Each letter in a pair is replaced with its corresponding partner, making it a simple but effective polyalphabetic-style substitution. It is often used as an educational example of fractionating substitution systems, similar in concept to the Atbash Cipher but with paired letter substitution.

The Simple Substitution Cipher is a classical monoalphabetic substitution cipher where each letter in the plaintext is replaced by a corresponding letter from a fixed, pre-agreed cipher alphabet. Unlike the Caesar Cipher, which shifts letters by a fixed number, the Simple Substitution Cipher allows a completely arbitrary mapping of the 26 letters, providing more variability and slightly stronger security against casual frequency analysis.

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.