Chapter 1 — Foundations

Caesar Cipher Explorer

Encrypt and decrypt with the Caesar shift cipher. Visualize letter mappings, analyze ciphertext frequencies, and auto-detect the key using the chi-squared statistic.

The Caesar cipher shifts every letter in the plaintext by a fixed number of positions in the alphabet. Despite its simplicity it illustrates the core idea of substitution ciphers and is easily broken by frequency analysis: comparing ciphertext letter frequencies to the known distribution of English reveals the key.
Plaintext
Ciphertext

Controls

Caesar (fixed shift)

Frequency analysis

Current status

Shift
0
Best χ²
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Chi-squared scores (all shifts)

Shiftχ² score