the limits of crypto and authentication

[Ben Laurie]

Peter Gutmann wrote:
> dan at geer.org writes:
> 
> 
>>Take a look at Boojum Mobile -- it is precisely the idea of using the cell
>>phone as an out-of-band chanel for an in-band transaction.
>>
>>http://www.boojummobile.com
> 
> 
> Banks here have been using it to authenticate higher-value electronic
> transactions as well.  The way it works is that for transactions with a
> combined value over the default floor limit of NZ$2.5K you have to use an
> additional PIN sent via SMS to a pre-configured number to authenticate the
> session.  The PIN authenticates that particular session (not just one
> transaction), with a fee of NZ$0.25.  It's not perfect, obviously, but that
> was seen as the best tradeoff between cost, user convenience, and security.
> 
> <grumble>A few years ago I wanted to do this out-of-band authentication as a
> research project, and at the time couldn't find anyone interested in it; now
> they've paid an arm and a leg for it themselves, sigh</grumble>.

Back when we used to run O2's (then Cellnet) web stuff, we used to 
authenticate user accounts by sending random words to their phone. This 
was so long ago I can't remember when it was, but certainly > 5 years.

Cheers,

Ben.

-- 
 >>>ApacheCon Europe<<<                   http://www.apachecon.com/

http://www.apache-ssl.org/ben.html       http://www.thebunker.net/

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