Paul Manifort recently pled guilty to witness tampering after contacting potential witnesses then denying it. He thought he was being clever by using WhatsApp to encrypt his phone calls and texts. Unfortunately Manifort backed up his chat logs in plaintext to Apple iCloud1, so the FBI just subpoenaed Apple for the chat logs. Simple.
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
Operational Security (OpSec) is a mindset not an app you can download. If the person with whom you’re chatting is uploading your chat logs to iCloud the entire communications chain is compromised. Likewise if they take screenshots of the chats or if they’re informants.
The only safe place to keep damaging letters is in the fireplace, between burning logs.
Never write if you can speak; never speak if you can nod; never nod if you can wink.
Also known as someone else’s computer. ↩