Vigenere Cipher Tool

Encode or decode a Vigenere cipher message with a repeating alphabetic key.

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This tool is for classroom cryptography exercises, puzzle checks and examples where a repeating-key Vigenere cipher is used.

What it does

Enter a message, choose encode or decode, and provide an alphabetic key. The result preserves spaces and punctuation while shifting letters by the repeated key.

Scope

Vigenere is a historical teaching cipher, not modern encryption. Do not use it for private or sensitive data.