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