Beaufort cipher
Please note that these tools aren't optimized for large amounts of data, processing can slow down or run into problems once you reach above 150,000 characters. A cap of 1 million characters is currently in place.
Beaufort cipher
Similar to the Vigenère cipher (the decryption process is the same), except you start with a reversed alphabet. For example: Hello encrypted with a key of Test would shift like:
H → T → M
e → e → a
l → s → h
l → t → i
- then loop back and start from the first letter in the key again. There is more information available on the Beaufort cipher Wikipedia page.