Which text encryption algorithm to choose?

Question

Character encoding

Good afternoon!
The mobile application sends a code (10-20 characters) to the server. The script on the server must decrypt this code - this is information from 32-50 characters. What type of text encryption will allow you to compress text from 32-50 characters to 10-20?
We need such an algorithm that it would be difficult to solve / sort out the cipher.
Thank you.

Answer 1

https?

Answer 2

Are there any other solutions?