This script will generate a table for you on stdout, based on the minimum and maximum characters in the range. Currently it will generate a table for all printable ascii characters, in order that they appear in the standard table. Modify the characters min/max in order they appear to change the range of characters you generate a table for.
This script will decrypt a message with a key, on the basis the message was encrypted with a tabula recta taking the form of the table generated by tabula.py.
In other words, you need to ensure that ascii_min and ascii_max each represent the minimum and maximum character in the ascii table standard order that was used by the person encrypting.
Currently the key and ciphertext are hardcoded under __main__, for the 44Con 2014 CTF challenge.