I am concerned by people's privacy in the Internet age, and the security that communication software and services offer, which is why I try to promote encryption in different everyday activities (emails with PGP, communication apps that offer end-to-end encryption, encrypted data on hard drives...). I consider that those issues are part of how "sustainable" a society is (for reasons that might not need to be explained in details here).
However, encrypting and decrypting a file uses extra processing power, and therefore extra electricity, when compared to a regular file transmission or read-write activity. How important is that difference, and does it have a significant impact on the overall environmental cost of our general use of computers?