Here’s a way that cash could be used to track you, based on some basic assumptions.
- Money is scanned (OCR, etc.) at the bank, and the serial numbers are reported to a central database.
- Identity of depositor is maintained with bills $20 and higher.
- The serial numbers on the bills are kept track of when the money is stacked in the ATM and the cashier drawers.
- Bills are given to consumers sequentially from ATMs and bank cashiers.
Joe consumer gets a stack of $20 bills at the ATM. He goes various places and spends the cash. When the retail stores in question get around to depositing that cash in the bank, it gets scanned again as coming from that retailer.
With this system and a little data mining, you could trivially place watches on a list of people to see where they spend their cash. Though there would be massive amounts of information to move around and process, if there’s a relatively small number of people to check serial numbers against, it could be manageable with relatively modest computer systems.
OK, so the fact that you shopped at Circle K and got a tank of gas, went to a particular grocery store where you presumably bought groceries isn’t all that exciting.
Of course, if you traveled cross-country stopping to pick up gas and grab a bite to eat with cash hoping to remain anonymous, your direction of travel could be monitored. Not in real-time mind you, but within a few days of the money changing hands, according to when cash pick-ups are made from various points, and how long before the cash is processed again.
So if you really want privacy from your cash, you’ll need to launder it (i.e. swap it with someone else for funds at least one step removed from a bank), or presumably storing your cash for a certain amount of time before spending it. There’s only so much data you can keep on the billions of bills in circulation no matter how big a computer system you have, so it would only keep information for a certain window of time.
What’s more interesting is those ‘Grocery Discount Club’ cards. These are potentially marvelously evil. You save your 10%, but now your complete purchase has your phone number, name and address associated with it. ALL of your purchases. Of course, using a debit or credit card to make the same transaction will similarly finger you. So the theory goes, various retail chains sell copies of the database to interested parties. Among them are health and life insurance providers. With a little bit of clever automated data mining, they can determine if you buy smokes, junk food, lots of red meat, etc. So they can ‘know’ if you have unhealthy eating habits, and can ‘adjust your rates’ accordingly.
The amount of data the credit companies have about you is downright awful.
Similarly, census microdata extracts are supposed to be ‘scrubbed’ so the identities of people can’t be determined, but using ever more subtle mining methods with ever more computational power behind it, census data has been ‘cracked’ to reveal individual identities. Of course, governments have used census data in scandalous things for as long as censuses have been taken. When the government its self abuses census data, there is no privacy at all. The Nazis had very accurate census data, and you know what they used it for. U.S. census data was used to track down Japanese Americans to send to internment camps, and more recently on Muslim Americans.
Here’s another slightly creepy one. A web spider service that looks for blog and forum posts to find negative opinions about your products. A fine use for such a system would be a company like Microsoft that wants to defend the reputation of its shoddy, bug-ridden products. You need to find a place to send your shills where they can do the most good.