A fair number of tech luminaries have been writing about Blippy recently – a new service which tracks your on and offline card purchases and shares them with followers. Not surpising with investors including Sequoia Capital, Jason Calacanis and Evan Williams. And Louis Gray has been publishing his experiences with the site.

I’m not averse to sharing my purchases and recommendations, and I’m fairly realistic about online security. Despite taking precautions, I’m aware that all banks and ecommerce sites have to transmit data, and that phishing and scam sites will always be a part of online life, as much as card cloning and skimming is a part of offline life.

I’m also happy to share a lot of info on social networks, only drawing the line at things which reveal more about my family than they might wish. After all, I’m choosing to let people know where I am or what they’re doing, but my family should choose their own privacy levels for themselves.

But surely there’s a big security risk inherent in the way Blippy works, which noone seems to have highlighted?

If you phone your bank or credit card company, they’ll generally require security details. And if you’re unable to provide them, or in addition, they’ll ask for you to reference a couple of recent purchases…

What does Blippy show? Recent purchases…

While I believe banks and other financial organisations should be adjusting their security to the new online world (and at the moment many are a bit subpar), it seems like a pretty big element of a financial security check to be sharing right now. So in the same way I’d happily use a location service to share when I’m in the pub but wouldn’t check into my home address, I think I’ll be giving Blippy a wide berth.