Dude, you're turning out to be a prime dickbag. This isn't a question of "wallet security", it's a problem of transaction fraud. Seeing as you couldn't come up with an answer, some others have come up with a partial solution. But there are still glaring holes in Bitcoin that will see it burn in an early grave if it ever hits the general population in its present form..
Uh oh,
name-calling - let me get something to cry into.
Transaction fraud discussions are in the forums too, you know, under the heading
"bitcoin escrow". Of course, you'd know this if you had bothered to look. Do you research anything you talk about,
ever? I'm quite sure by the time any of these problems are solved, it won't be because you posted a few hurried statements about bitcoin in your spare time.
Either offer some kind of strategy yourself, learn about the complexities, or stay out of the way of those who will solve it for you.
Sorry, buddy, you continue to mark yourself as a dickbag. Escrow is obvious, but it introduces the problem of a third party. This is a fundamental flaw as any conventional escrow would be subject to regulation. Escrow makes Bitcoin no different to a bank or paypal transaction. As such, Bitcoin is just a geeky reinvention of the wheel.
The nearest thing to a resolution offered so far is the "web of trust", offered by a more constructive poster than yourself earlier in this thread.
But remember, if Bitcoin goes mainstream gangs of very smart people will be looking to attack it.