I need a python programmer for a simple program

Program should encrypt/decrypt given file using a simple XOR cipher with the given key file. So when the XOR cipher is applied to the now encrypted file, it should return the original file in the original format. Given/Inputs: two text files File 1: multiline text file: needs to be encrypted/decrypted with a simple XOR cipher using the key-file given. File 2: Key text file: will be a file of size ranging anywhere from 10 bytes to 10 Petabytes, containing random bytes. Output: A new text file containing the encrypted/decrypted data from File 1 above. Caveats / Catches / Rules: using pre-supplied libraries, packages, modules, etc. for the XOR encryption is not allowed. XOR is done character by character using their corresponding ASCII values. The Key file can be bigger or smaller than the file to be encrypted/decrypted. No need to prompt user for filenames.