Cipher Encyclopedia
All 22 classical ciphers across 7 cryptographic families. Click any card to learn more.
One of the simplest ciphers — each letter is shifted by a fixed number of positions in the alphabet.
Combines multiplicative and additive encryption. Each letter is encrypted using a linear function.
A fixed substitution cipher where the alphabet is reversed (A↔Z, B↔Y, etc.).
Uses a repeating keyword to shift each letter by a different amount, creating multiple substitution alphabets.
Like Vigenere but uses the plaintext itself as part of the key after an initial priming key, preventing key repetition.
Similar to Vigenere but uses reciprocal subtraction. Encryption and decryption use the same operation.
Uses a tableau of 13 reciprocal alphabets. The alphabet is split into halves (A-M and N-Z) with key-dependent swaps.
Writes plaintext in rows, then reads ciphertext off in columns according to a key-based permutation.
Encrypts pairs of letters (digraphs) using a 5×5 key square. Same-row, same-column, and rectangle rules determine substitution.
Uses matrix multiplication to encrypt blocks of letters simultaneously. The key is an invertible matrix mod 26.
An extension of Playfair using four 5×5 grids (two standard, two keyed) for stronger digraph encryption.
Combines a Polybius square with transposition. Coordinates are split, concatenated, and re-paired for diffusion.
Extends Bifid to three dimensions using a 3×3×3 cube. Each letter maps to three coordinates for stronger diffusion.
A WWI German cipher combining Polybius substitution (using only letters A, D, F, G, X) with columnar transposition.
Extension of ADFGX to support all 36 alphanumeric characters (A-Z + 0-9) using a 6×6 grid.
Combines Polybius square encoding with keyword addition. Produces numeric output as space-separated two-digit numbers.
Tiny Encryption Algorithm — a simple 64-bit block cipher with 128-bit key using 64 Feistel rounds and the golden ratio constant.
Extended TEA — an improved version of TEA with a more complex key schedule to prevent related-key attacks.
An early IBM block cipher and the direct precursor to DES. Uses a 16-round Feistel network with S-boxes.
A DES alternative using a 64-bit block and 64-bit key with a 16-round Feistel network and complex S-boxes.
A 64-bit block cipher with 128-bit key using an 8-round recursive Feistel structure with nested FO and FI functions.
Replaces each letter with its row and column coordinates in a 5×5 grid, producing numeric output.