Web Tools
Vigenere Cipher
Encrypt and decrypt text using the Vigenere polyalphabetic cipher with configurable key, case preservation, and non-alpha handling. Runs entirely in your browser — your data never leaves your machine.
cipher encryption decryption vigenere cryptography
Published May 30, 2026
All interactive tools run entirely in your browser. Your data never leaves your device.
How It Works
Enter your text and a keyword, then choose encrypt or decrypt. Each letter is shifted by the corresponding letter in the key using the Vigenere tableau.
Features
- Encrypt and decrypt: bidirectional Vigenere cipher
- Case preservation: maintains original letter casing
- Non-alpha handling: optionally preserve spaces, punctuation, and numbers
- Key normalization: strips non-alpha characters from key, case-insensitive
- 5 examples: classic encryption, decryption, mixed case, punctuation, long key
- Private: runs entirely in the browser — no data transmitted
Use Cases
- Learning classical cryptography and polyalphabetic ciphers
- CTF challenges and puzzle solving
- Teaching the Vigenere cipher in computer science courses
- Encoding messages for fun or educational purposes