Transposition

The AMSCO Cipher is a transposition cipher that rearranges the letters of a message using a keyword and an alternating cell pattern. Unlike simple columnar transposition, AMSCO alternates between placing one and two characters in each cell, following a continuous pattern (1-2 or 2-1) across the entire message.

The Index Card Cipher is a manual polyalphabetic substitution cipher that uses a set of shuffled alphabets (cards) to encode plaintext. Each card represents a full alphabet in a predetermined, scrambled order. By arranging and cycling through these cards according to a numeric key sequence, the plaintext letters are substituted in a way that depends on both the card and the position of the letter, increasing encryption complexity.

The Cardan Grille cipher is a classical steganographic and transposition cipher invented by the Italian mathematician and polymath Girolamo Cardano in 1550. It is notable for its use of a physical device—a perforated grille—through which a plaintext message is written on a blank sheet of paper. The holes in the grille determine which letters are visible, while the remaining spaces are filled with nulls or random letters, creating a concealed message.

The Columnar Cipher is a classical transposition method that encrypts a message by rearranging entire columns of text according to a keyword. Unlike substitution systems such as the Caesar Cipher, the letters themselves are not altered — only their positions are changed.

It expands upon the simpler Columnar Cipher by explicitly reordering columns based on the alphabetical ranking of the keyword. This column permutation is the defining feature of the cipher.

The Kangaroo Cipher is a simple substitution cipher that uses a keyword to generate a variable shift pattern across the plaintext. It is similar in concept to the Caesar Cipher but instead of a single uniform shift, each letter is shifted according to the corresponding letter in the keyword, which repeats across the message.

The Transposition Cipher is a classical cipher technique that rearranges the letters of the plaintext according to a defined system, without changing the letters themselves. Unlike substitution ciphers, where letters are replaced with other letters or symbols, transposition ciphers preserve the original letters but change their positions to create the ciphertext.

The Spiral Cipher is a transposition cipher that arranges plaintext into a grid of a specified number of columns and reads the letters in a spiral order. Spaces are preserved in their original positions, and padding characters (·) are added only to fill incomplete grid cells to maintain a rectangular shape.

The Scytale Cipher is an ancient transposition cipher used by the Spartans. A message is written along the length of a cylinder (or strip of parchment wrapped around a rod), and the ciphertext is read by unwrapping the strip and reading column by column. This method rearranges the letters of the plaintext while preserving all characters, providing basic encryption.

The Route Cipher is a columnar transposition cipher that rearranges letters of a plaintext into a grid defined by a keyword. Letters are then read off column by column in alphabetical order of the keyword letters. Spaces are removed during encoding, and if the last row is incomplete, it may be padded to fill the grid. The recipient decodes by reconstructing the grid and reading row by row.

Its security relies entirely on the secrecy of the keyword. It does not substitute letters but only rearranges them.

The Rail Fence Cipher is a classical transposition cipher that rearranges the letters of a plaintext message into a zigzag pattern across multiple "rails" (rows) and then reads them sequentially row by row to form the ciphertext. It is a simple but effective method for obscuring the order of letters, making it harder for casual observers to read the message without knowing the number of rails used.