The first book: substitution and transposition, the foundations every later cipher is built upon. Choose a method, work the text, and watch the path — the alphabet, the key stream, the grid. The lesson is never the table; it is the key.
Paste a message, choose a method, and read the ciphertext. The work panel below shows exactly how each letter was moved, so the result can be re-derived rather than trusted.
Trithemius set twenty-six alphabets in a square, each shifted one place from the last. Row = key letter, column = plain letter, crossing = cipher. When the method above is Vigenère, the grid lights the path of the last letter enciphered.
The same grid, relabelled with spirit-names, is how the original hid its method in plain sight. Method and disguise are one object.
Auto-run on the current input. The index of coincidence separates a monoalphabetic cipher (near English, ~0.067) from a polyalphabetic one (flatter, near random, ~0.038).
Every panel exposes its intermediate state. A surprising plaintext without a reproducible path — an alphabet, a key stream, a grid — is treated as noise, not a solution.