0

Decoded

Vigenère
Key (A-Z)

Encoded

Vigenère
Key (A-Z)

About Vigenère Cipher

Vigenère cipher is one of the single transliteration ciphers that encrypts by replacing the characters in the text with other characters.

Character replacement is performed using the encryption key and the following Vigenère square.

ABCDEFGHIJKLMNOPQRSTUVWXYZ
AABCDEFGHIJKLMNOPQRSTUVWXYZ
BBCDEFGHIJKLMNOPQRSTUVWXYZA
CCDEFGHIJKLMNOPQRSTUVWXYZAB
DDEFGHIJKLMNOPQRSTUVWXYZABC
EEFGHIJKLMNOPQRSTUVWXYZABCD
FFGHIJKLMNOPQRSTUVWXYZABCDE
GGHIJKLMNOPQRSTUVWXYZABCDEF
HHIJKLMNOPQRSTUVWXYZABCDEFG
IIJKLMNOPQRSTUVWXYZABCDEFGH
JJKLMNOPQRSTUVWXYZABCDEFGHI
KKLMNOPQRSTUVWXYZABCDEFGHIJ
LLMNOPQRSTUVWXYZABCDEFGHIJK
MMNOPQRSTUVWXYZABCDEFGHIJKL
NNOPQRSTUVWXYZABCDEFGHIJKLM
OOPQRSTUVWXYZABCDEFGHIJKLMN
PPQRSTUVWXYZABCDEFGHIJKLMNO
QQRSTUVWXYZABCDEFGHIJKLMNOP
RRSTUVWXYZABCDEFGHIJKLMNOPQ
SSTUVWXYZABCDEFGHIJKLMNOPQR
TTUVWXYZABCDEFGHIJKLMNOPQRS
UUVWXYZABCDEFGHIJKLMNOPQRST
VVWXYZABCDEFGHIJKLMNOPQRSTU
WWXYZABCDEFGHIJKLMNOPQRSTUV
XXYZABCDEFGHIJKLMNOPQRSTUVW
YYZABCDEFGHIJKLMNOPQRSTUVWX
ZZABCDEFGHIJKLMNOPQRSTUVWXY

The top row is the plaintext before encryption, the left column is the encryption key, and the characters they intersect are the characters after encryption. The encryption key is a string from 'A' to 'Z'.

For example, if the plaintext before encryption is "MESSAGE" and the encryption key is "SECRET", the characters are replaced and encrypted as follows. Since the first letter is 'M' and the key is 'S', the encrypted letter will be 'E'.

Plain text : MESSAGE
Key      　: SECRETS
Cipher text: EIUJEZW

One character of the encryption key is used for each character of plaintext. If the key length is shorter than the plaintext, use the key repeatedly.