Secrecy—stealth—is not a preserve of the human species. It is a matter of survival for all our brothers, sisters and cousins in the animal world from which we have evolved. Whether in times of peace or in times of war, we all harbor secret thoughts, feelings, desires, objectives, and so forth that we want to share only with those we absolutely trust, and that we want to carefully conceal from those who would take advantage of us if they knew what we had in mind.
A Tutorial for Beginners to PGP
I love this philosophical take on encryption. - Deji