Vigenere Cipher
Encode and decode text with a keyword-based Vigenere cipher.
The keyword shifts each letter by a different amount. Only letters are changed; spaces, numbers and punctuation stay the same.
The Vigenere cipher is a classic method for learning and puzzles. It is not secure for real secrets; use AES encryption for that. Everything runs in your browser.
About the Vigenere Cipher
Encode and decode text with the Vigenere cipher, a classic method that shifts each letter by a keyword.
Because the shift changes with each keyword letter, it is stronger than a simple Caesar cipher and a favourite for puzzles and learning.
Only letters are changed; spaces, numbers and punctuation are kept as they are.
Key features
- Encode and decode with a keyword
- Keeps spaces, numbers and punctuation
- Preserves upper and lower case
- Copy the result instantly
How to use
- 1Choose encrypt or decrypt.
- 2Enter your text and a keyword.
- 3Copy the encoded or decoded result.
Examples
HELLO with key KEYRIJVSEach letter is shifted by the matching keyword letter.
RIJVS with key KEYHELLOThe same keyword reverses the shift.
Frequently asked questions
- Is the Vigenere cipher secure?
- No. It is a classic cipher for learning and puzzles and can be broken. Use AES encryption for real secrets.
- What makes a good keyword?
- A longer keyword with varied letters is harder to break than a short or repetitive one.
- Is my data uploaded?
- No. Everything runs in your browser.