Using Keys to Encrypt Messages

Question

Hello people good night. :D
Introducing the problem directly: I'd like to know how methods that encode a string using another string as a key. For example, I created the following code in hastebin:
https://hastebin.com/soqofaxava.makefile
(I'm sorry for posting to an external site. My cell phone was stolen and I can not access the Sololearn application and consequently I could not search the encryption classes.)
In short, I already have the method of encoding, it is this: https://code.sololearn.com/cRKdDSnshp99/#py
Now I'm trying to improve it, make it more secure. For this I am implementing a system of users in which each one has specific keys and, thus, only sender and receiver can decode a message. Here is the repository with the work created so far: https://github.com/Faherya/s.py
And that's it. Thank you very much for your attention, guys. O/

Answer 1

Thank you very much, I'll research about it. o/

Answer 2

For purpose, 3DES use with MD5 encryption