An argument for ditching less secure means of communicating in favour of more secure and open source software and services with end-to-end encryption support.

An introduction to two-step authentication, HOTP and TOTP algorithms, with an example in Python on Heroku using Flask and pyotp and the Google Authenticator app for client-side.

An introduction to RSA cryptography, with accompanying Python code implementing the basic algorithms used. A quick review of the number theory and group theory involved is given as well.