Interesting take, hadn't thought of that at all.

Something along those lines would definitely be boon to AAPL or others penetrating that sort of market. However, we all know the software on smartphones are if not trivially, at least often manipulated. This may be able to skim a little of the market, but if I had a business where I couldn't trust camera phone now, I wouldn't trust this technique against even a slightly educated and motivated individual.