Cracking a Substitution Cipher

About this app

Frequency analysis, hands-on: the ciphertext sits on top, a mirror chart below. Ciphertext frequencies grow upwards, the German distribution hangs downwards, and the assignment strip lies in between. Letters are assigned by dragging or tapping, and the plaintext appears bit by bit. Three levels: Caesar with a shift slider, substitution with visible spaces, and the 27-symbol version from the slide. Despite 27! ≈ 10²⁸ keys, six assignments make SIE, IN and ES readable. With Hint and Check.

Subject: Cryptography

More from Cryptography

• The Nonce Lottery
• Hashing & collisions
• Pseudorandomness — how a computer rolls dice
• SHA-256 in slow motion (8-bit model)
• Encrypt and Sign with Two Keys

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