No pannier lock is secure. They're all just deterrents.

I've broken into tons of panniers at work. Lost keys etc. It's really easy.

If you consider that the average pannier skiln is really thin, you can just pry off a lid by distorting it around the lock using a claw hammer, pry bar, large screw driver etc. You can stab your way though a pannier wall with a Philips screwdriver too. Easy !

The most secure would be a hasp and staple. Use stainless steel fan screws so they're hard to drill and can't be undone. Even better, have the hasp and staple TIG welded onto the case.

The only downside is that you need padlocks and they can rattle around. Although there are ways to stop this. And of course they can still be removed with bolt croppers/grinder. But still much better than the shite locks on panniers.

A bike cover is probably a bigger deterrent than better locks.

Well I finally found a supplier and bought 200 of them

Can be used as a hinge, latched without a key or locked completely with a key
Top quality similar to Touratech OEM latches

If anyone wants to buy some go to www.adventurefirst.com.au

Hope this helps someone out there

These are the people I've bought stuff from when I've been making my own panniers / boxes etc.

https://www.craven-equipment.co.uk/i...-locks-handles

It's all old school technology but solid enough and good enough for my needs. As Ted said there's little point in going crazy with lock security when it's so easy to get round if you're determined. A bit like welding the door shut and leaving the window open.