> Governments have all sorts of things like machine guns, tanks, and battleships that (rightfully) aren't allowed for the general public.

You have listed three things which are all really the same thing. There is no objection to private ownership of motor vehicles or ships. You object to the weaponry.

But we can put aside the whole right to bear arms debate in this case because there is an obvious way to distinguish it. Encryption is a purely defensive technology.

It is totally illegitimate for a government to prohibit things like armor and electromagnetic shielding, even if some of them do, because these things only defend, they do not attack.

Secure communication is not a purely defensive technology. It allows you to safely coordinate an attack.

By this logic home ownership is an offensive technology because it allows you to safely coordinate an attack.

And indeed it would be. Conversely, if you only used a gun to defend your self it would be a defensive technology. Seems like classifying technology as either offensive or defensive is a fool's errand. Perhaps you should try a different argument.

One could maybe play silly rhetorical games like "It wasn't the gun that killed him, it was the bullet", but to say "It wasn't the gun that killed him, it was the house that the killer lived in while she thought about committing the crime" is beyond ridiculous.

I feel quite comfortable classifying encrypted messaging apps in the same category as houses and chain mail, even if the US government has historically disagreed.

> And indeed it would be.

Only if that logic is sane, which it isn't.

There is an difference between doing something directly and indirectly. Anything can do anything given enough indirection. There is no plausible way in which your ordinary use of encryption or body armor could directly harm anybody else. There are some immediately obvious ways that your ordinary use of a howitzer could directly harm somebody else.

And the right to defend yourself using indirect offensive measures has no inherent symmetry with the right of government (or lack thereof) to prevent you from defending yourself using direct defensive measures.

Ransomware uses encryption to harm people.

Not really. Ransomware works by creating an encrypted copy of your data and then deleting the original data. The direct harm comes from deleting the original. Where would the harm be if all they did was create an encrypted copy without deleting the original?

And the same attack works if instead of encrypting your data they upload a copy of it to their servers before deleting it. Albeit less efficiently, so we're back to indirect harms.

Being alive allows you to safely coordinate an attack.

Sadly, no one actually has any battleships these days, not even the governments... :-(

We call them "destroyers" nowadays.

(The Zumwalt-class destroyer displaces ~15,000 tons, which is too large to be considered a cruiser under the terms of the inter-war naval treaties, and is roughly the displacement of a 1910s-era South Carolina-class battleship).

Thats still less than a half of the displacement of Warspite, third of the Iowas, let alone monsters like the Yamato class. And unlike Zumwalt, all of those had working guns. ;-)

On a more serious note a modern destroyer could sink any of those with long range missiles long before the batlleship could ever get into a range for a proper gun duel.

Not counting modern aircraft with yet more standoof missiles or even the anti/ship ICBMs that are being talked about.

Oh well, battleships were an elegant weapon for a more civilized age...

Because these days a battleship is mostly a very expensive missile practice target.

And there were times countries had lines of battle of these missile targets spanning the horizon - imagine that! :)

Somehow these just look so much more elegant than just spamming more bombers and nukes. Maybe because they usually only caused death of the sailors crewing them and other warships in battle rather than city populations like bombers and nukes often do ? (Well, unless you live in Yarmouth or on the River Plate.)