Gronsfeld

This operates very similar to a Vigenère cipher, but uses numbers instead of a key word.

The Gronsfeld cipher is essentially a Vigenère cipher, but uses numbers instead of letters. So, a Gronsfield key of 0123 is the same as a Vigenère key of ABCD. This online version lets you encode and decode messages with a keyed alphabet as well, to allow for maximum flexibility.

Examples:

Operating mode:

Alphabet:
Alphabet key:
Use the last occurrence of a letter instead of the first
Reverse the key before keying
Reverse the alphabet before keying
Put the key at the end instead of the beginning
Resulting alphabet: ABCDEFGHIJKLMNOPQRSTUVWXYZ

Cipher key:
Vigenère equivalent key:

Show Tableau

Use "autokey" variant to extend the key with plaintext (not typical for Gronsfeld)

Message to encode or decode:

Remove: letters, numbers, whitespace, other things
Change: lowercase, Natural case, Title Case, UPPERCASE, swap case, reverse
Make groups of and next line after groups

Enter text and see the result here