Vigenère Cipher

Encrypts, decrypts, and attempts to find the key if it is unknown for the vigenere cipher

Encryption

• Enter 'ENCRYPTION' when prompted
• Enter plaintext to encrypt
• Enter key to encrypt with
• Encrypted text is output

Decryption (with a key)

• Enter 'DECRYPTION' when prompted
• Enter ciphertext to decrypt
• Input 'Y' to indicate that the key is known
• Input the key
• Decrypted text is output

Decryption (without a key) - the program will attempt to find the key

• Enter 'DECRYPTION' when prompted
• Enter ciphertext to decrypt
• Input 'N' to indicate that the key is not known
• Input a maximum key length to check for. This must be greater than 0 but less than the length of the ciphertext. Note that a larger maximum key length will be slower.
• The most likely key length to the least likely key length is output
• Input a key length to use
• Keys will be output, ordered by the most likely key to the least likely key
• Input a key to use. Inputting '1' will automatically select the most likely key.
• Decrypted text is output