Because arphids can be read from greater distances, they can be used for additional purposes, where bar-codes cannot. For instance reading bar-codes of products stacked on a shelf would be a very-labor intensive operation, however reading arphid data from a similarly stacked shelf would be much easier since each item would transmit its own data when queried. This long distance reading capability also presents a security risk if the data stored on the arphid is of a sensitive nature. The arphid has no authentication mechanism so anyone with a proper reader can query and arphid. Unless the data stored on the arphid is encrypted then it will be available to anyone. Products labeled with arphids will be trackable to a far greater degree than a bar-coded product and this means even after you purchase a product and take it home the data on it could still be read. This greater availability of product data is seen as a loss of privacy by some. 
Arphids can have enough memory available to hold a significant amount of data. Your driver’s license, passport or insurance data could be stored in a single arphid. This data would be remotely readable so while you would have easy access to the data, so would someone else! Although encrypting the data would protect it, if the encryption scheme were deciphered then the data could be stolen without your knowledge. Passports, medical records and driver’s licenses are among the legal documents under consideration for arphid use. Since arphids are initially programmed with the data they hold, it may be possible to rewrite the data stored in the arphid, even from a remote location. While an arphid’s serial number could not be changed, the remaining data could be changed maliciously. Even if all of an arphid’s data could not be read, the arphid’s use of a anti-collision protocol means that the last digit of the arphid’s serial number could be leaked without a direct query.
Article comments
1 - [GEEKS ARE SEXY] Tech. News
It was in the news recently that RFID chips could get infected by some new kind of viruses.. for those that are interested in this subject, you might want to have a look at this site that explains the process in detail.
Cheers!
Kiltak
[Geeks Are Sexy] Tech. News
2 - John Vaccaro
Turns out that the virus was information stored on the chip which when fed into a vulnerable backend system caused a problem. If the vulnerable system had been patched and/or the backend properly designed whetever is stored on the arphid would not negatively impact the system as a whole.
3 - iTech
I agree with the posts above. RFID does not receive as much attention as it should be. The above link provides a valid find about vulnerabilities. In addition RFID tags pose a huge privacy issue as it would not only be used in commercial areas but also for tracking purposes.
Does everyone have their tin-foil hat on?
4 - DIFRWear
I recently started up a company that sells RFID blocking wallets and passport cases. Take back control of your privacy. gizmodo post
5 - jesus
Mark of the beast <- look that up
6 - Alex Jones
wow thats crazy, in the bible it states that "thou shall not wear the mark of the beast, which in this case is the RFID chips soon to be implanted into everyone
7 - Lex
DIFRWear, I guess when you open your wallet you are screwed, hopefully she's blond and cheap.
Nice invention!
Lex
8 - yoozeguyz
Just FYI, "RFID for Dummies" is not the definitive work on RFID...it has more than a few factual errors in it (this from some of the people who contributed to it). [And please, it's "RFID" (Radio Frequency ID) not "arfids."] But, the more you learn about the various forms of RFID (and the underlying physics), the less scary it becomes (in fact, its performance is pretty wretched in many applications). Yes, some types of RFID tags can be "hacked" (but it's much harder when security and good database design are really employed) but you're more in danger of having the computer you use corrupted by worms, trojans and viruses.