Playfair cipher

Client

Encrypt or decrypt letter pairs with a 5×5 Playfair square—historical digraph cipher used in field manuals and crypto history courses.

About Playfair cipher

Classic Playfair digraph cipher with a keyword—reversible substitution in your browser. The interactive transform on this page runs in your browser tab—Toolcore does not need your paste for the core operation described above.

How to use this page

Paste or type in the main workspace, run the primary action from the toolbar, then copy or download the result. Use Load example when the page offers it, or URL prefill (?q= / ?qb=) so agents and tickets open the same input.

Limits and safety

Utilities here are for development and inspection—do not paste live production keys, PANs, or recovery codes into any browser tab you do not control.

CFSUPM

Nearby workflows on Toolcore

  • Vigenère cipher — Encrypt or decrypt A–Z with a repeating keyword—classic polyalphabetic cipher locally. before you trust a token, digest, or key material in production.
  • Affine cipher encoder — Map A–Z with (ax+b) mod 26—enter a,b coprime to 26 for a valid key. before you trust a token, digest, or key material in production.
  • Atbash cipher — Encode or decode text with Atbash letter substitution (a↔z)—reversible, in your browser. before you trust a token, digest, or key material in production.
  • Rail fence cipher — Encode or decode zigzag rail fence transposition ciphers—configurable rails, in your browser. before you trust a token, digest, or key material in production.

Common use cases

  • Encode short messages for puzzles or classroom demos.
  • Compare Playfair with Vigenère and other classical ciphers.

Common mistakes to avoid

  • J in plaintext

    J is merged with I in the square and text, as in classic Playfair.

FAQ

Is this secure today?

No—Playfair is educational only; use modern crypto for real secrets.

Odd length?

An X padding letter is added when needed.

More tools

Related utilities you can open in another tab—mostly client-side.