Keyed on/off switch for security?

I'm working on my first ever e-bike - front geared hub on a Yuba Mundo with a Cycle Analyst V3 and Infineon controller. I bought everything as a kit from em3ev and it came with this cheesy light/horn on-off switch, which I was told needed to be wired in to actually turn the whole system on and off. Of course it doesn't fit on my handlebars with the lever type thumb throttle I bought, so I found another on-off switch online that has only one button and not the superfluous horn button. However, I was doing some reading and found a lot of folks seem to install keyed switches as an on-off switch in place of the bar-mounted button. I lock up my bike anytime I leave it anywhere, but it occurred to me that a keyed switch would be safer since with just the on-off button on the handlebar, any unsupervised kid waiting while mom is talking to someone else can touch the bike and inadvertently turn it on and possibly even engage the motor, even though the bike would be locked to a rack. At the very least I don't want a switch being bumped and having the thing turn on when I'm not around. Can a keyed switch simply be installed in place of that bar-mounted on-off switch? I've read a bunch of different threads about these switches and can't make heads or tails of it. I think the way my motor/controller/display is supposed to be wired, the on-off switch plugs into the Cycle Analyst and through it turns off the display and presumably the controller. I keep reading about other guys installing switches between the motor and controller and all sorts of stuff about voltage arcs, and switches burning up frequently, etc. Obviously I want a on-off switch for safety, but also I guess as a security measure as well. Suggestions?

If your controller has a "keyswitch" or "ignition" wire, you can put the keyswitch in that wire. If you're not sure, ask the vendor (EM3EV?) if it does and which wire it is. Then there's no sparks/current/etc. to damage the switch.

Anything that can interrupt that key switch can work as a key. A not so easy to find switch, a plug you pull that a thief won't immediately find, a keyed switch, removing 6 inches of the wire by unplugging it, etc.

All will work fine to switch the bike on and off. One of my tricks used when I stripped a switch off a bike, was a bread tie wire stuck in the plug to complete the circuit. Worked fine. Show me the thief that would figure that one out.

Personally I don't bother. I use a non keyed switch on the bars, and a lock, and try not to park where a thief will nab it easy. I shop in the AM, while they are sleeping off the drugs and booze. Not parking it stupid is my main defense. When I commuted, I had a secure enough place to park unlocked.

I bought a cheapest key switch available online ca. 1-2$ delivered. It has a very simple "round" key with just one tooth.

With infineon EB318 works perfect. I even lower a step down converter directly from it to power lights and a cell phone charger.

The only drawback is that you need to put the key into your pocket after ignition, because it doesn't hold the key.