shift_system = ShiftCryptosystem(AlphabeticStrings()) message = "The shift cryptosystem generalizes the Caeser cipher" plaintext = shift_system.encoding(message) print("plaintext:", plaintext) key = 7 encode = shift_system(key) ciphertext = encode(plaintext) print("ciphertext:", ciphertext) decode = shift_system(shift_system.inverse_key(key)) print("Decoding ciphertext gives plaintext?", plaintext == decode(ciphertext))
I want to shift backward to decrypt, but when I write k=-7, it it error that k is outside of range, so how can I correct it?
