What is the Vigenère cipher?

The Vigenère cipher shifts each letter by a different amount, set by the letters of a keyword. With the key LEMON, the first letter shifts by L (11), the second by E (4), and so on, starting over when the key runs out. That makes it much harder to crack than a Caesar cipher.

Enter the key and choose decode or encode. Spaces, numbers and punctuation are kept and do not use up key letters, which matches how most puzzle caches write it. If you do not know the key, look for a word in the cache title, description or hint.

Example

LXFOPV EF RNHR with the key LEMON decodes to ATTACK AT DAWN.

Number keys

If the key is a number, like 31415 or a year, type it as the key. Each digit shifts one letter by that amount. This version is called the Gronsfeld cipher.