On 7/23/2010 4:58 PM, doc@kd4e.com wrote:
> I presume that these are the type that only "transmit" when
> the scanner induces enough energy inductively to cause them
> to do so?
>
They do sound like RFID tags and are identified as such in the first
article linked. They are also listed as removable.
RFID tags are passive devices so the distance they can be read depends
on the strength of the transmitted signal to activate them and the
strength of the return signal as well as the sensitivity of the
receiving device. "As advertized" (my spell checker is trying to use
the UK spelling) the tag and receiver (which also contains the
activating transmitter, but does not need to) need to be fairly close to
each other. IE, just a few feet or up to about 20 feet in some
instances. However "It's my understanding" modified equipment can read
tags up to a 100 feet or more. There have been experiments of
checkouts, highway tolls and other implementations where you don't even
need to get the card out, or get the card out, but don't have to swipe
it through a reader. I believe these setups use different equipment and
different cards BUT I do know of companies that have badges that check
you in as you drive through the gate, and library cards you do not have
to get out to check out a book. I have one of the latter although if I
don't check out a book for some time they may want to see the
signature. Both of those cards operate on a different principle than
the RFID tags. They also drive each other nuts. IOW the library cards
screw up the badge reader and the ID cards mess up the library card
readers. The library has a sign by the check out that asks people from
companies using those badges to "PLEASE" leave their badges in the car,
but most don't due to the responsibility involved.
> http://online.wsj.com/article/SB10001424052748704421304575383213061198090.html?mod=rss_whats_news_us&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+wsj%2Fxml%2Frss%2F3_7011+(WSJ.com%3A+What's+News+US)?test=latestnews
> <http://online.wsj.com/article/SB10001424052748704421304575383213061198090.html?mod=rss_whats_news_us&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+wsj%2Fxml%2Frss%2F3_7011+%28WSJ.com%3A+What%27s+News+US%29?test=latestnews>
>
> BTW: Is an aluminumized static bag sufficient to shield credit
> cards and driver's licenses from undesired scanning or is something
> more robust required?
>
No, and yes. Passports come in a magnetically shielded envelope and
something like that would be required to keep that particular type of
card from being read..
Within the computing industry it has been remarked that this is a poor
way to keep sensitive information even with the security measures in
place. Early cards had little in the way of security, then if I
understand they had some secure hand shaking. I believe the information
on passports is now encrypted (but don't know for sure). Still, if a
scanner picked up encrypted or a nonsensical return in a crowd it'd
pretty well identify you as a US citizen.
However I'd add that so far I believe the card and scanner relation is
still pretty secure. It'd be far easier to just get the card numbers or
actual cards via other methods.
At one time RFID tags were using the 440 band, but I believe they are
now some where in the 900 MHz range, but do not know that for sure.
73
Roger (K8RI)
> Just curious ... :-)
>
>
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