Vigenère Cipher Workbench

Vigenère Decoder

Vigenère ciphertext

AlphabetOrder matters. Every character must be unique.

Preserve punctuation and letter case

Plaintext language

Decryption method

Automatic cryptanalysisKasiski evidence, index of coincidence, and frequency scoring Knowing the key/passwordExact deterministic decryption Knowing the key lengthInfer one shift per key column Knowing a partial keyUse ? for unknown letters Knowing a plaintext wordTest consistent crib positions and key lengths

Key/password

Number of key letters

Partial key

Known plaintext word

Best plaintext result

Vigenère Encoder

Plaintext

Preserve punctuation and letter case

Cipher key

Alphabet

Ciphertext

Show Vigenère square / Tabula Recta

Generated from the decoder alphabet. Large custom alphabets create large tables.