[RFI] Wal-Mart to Put Radio Tags on Clothes - WSJ.com

[Roger (K8RI)]

On 7/23/2010 4:58 PM, doc at 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 ...  :-)
>
>