How to encrypt files in python?

Question

Encryption

Is it possible to convert each character in a file (for example .txt) to ASCII and make one large digit from the resulting digits (by multiplying for example), and then multiply this large digit by the key, which will be the decoder?
Or am I missing something and this method won't work?

Answer 1

Article about encryption

Answer 2

The first rule of encryption is not to come up with your own encryption algorithms.
If it seems that everything is safe and reliable, then it doesn’t seem so to modern cryptanalysts, serious ciphers are developed by serious mathematicians and undergo dozens of audits, so it’s impossible to come up with something of your own even close to similar.

Answer 3

And how to restore the original txt from this large first digit obtained by multiplication? Or am I missing something too?