As others have alluded, the attack surface on a smartphone is too large to ever be secure against sophisticated and wealthy adversaries. The regimes most inclin

As others have alluded, the attack surface on a smartphone is too large to ever be secure against sophisticated and wealthy adversaries. The regimes most inclined to spy are the same ones who spend the most on point-and-shoot exploits to own your phone. Best answer from a US perspective is Michael Bazzell's work, with product specific to mobile phones having just been released: https://inteltechniques.com/book7a.html https://inteltechniques.com/book7a.html