What If: Plastic Banknotes
Introducing a new type of article from me, where everyday things that we take for granted are looked at through a different (darker) lens to show what could be (or might already be). The starting point for this series looks at cash and its (so-called) anonymity. Perhaps things aren't as anonymous as we thought...
In September 2016 the first polymer-based banknote was introduced in the UK (specifically the £5 note), which paved the way for replacing all existing banknotes with their plastic counterparts. On the face of it this was a change for the better, as the new notes were less susceptible to damage, would last longer, had better anti-fraud measures than their paper counterparts, and in some cases could survive a trip through the washing machine. The presented rationale for the switch made sense, but what if there was another reason that wasn't public knowledge?
Plastic surfaces are great at repelling water but not so good at keeping off marks from oily contact, such as the fingertips from a bare hand. While barely visible to the naked eye, transfer from fingertips does take place to every surface we touch. In most cases we don't think anything of this (unless you are trying to commit a crime), and with banknotes that change hands so often it doesn't seem like a concern, but what if there was more to it.
If the goal of an organisation was to track the flow of money from person to person, there are a few ways to do it (depending on the situation). Marked notes is one of them, but depending on the type of mark (i.e., UV) it can be spotted more often than not. Using the serial number of each note is another way, but on its own it doesn't present a full map of who has had contact (just specific points on its journey). A possible approach (hence this article) is that of reading the fingerprints from each side of a note, and correlating that against its serial number. With this, tracking becomes significantly more detailed.
The big question is, how would an organisation go about this? Starting at the source, you ensure that banknotes are pristine (i.e., unmarked by fingerprints) when they are deployed to each branch / ATM (logged of course). This ensures a clean starting point, with the serial number of each bill logged. Then, you upgrade the scanners in each bank / cashpoint so that when the usual security check on a note takes place (i.e., the UV light a note is commonly shined under) you also take a high-resolution photo at a different wavelength (one that highlights fingerprints / oils). This image is sent for processing, where the stacked fingerprints (as banknotes recirculate) are parsed layer by layer. Each print is scanned / matched / logged against the serial number, giving a timeline of contact. This also works in reverse, as when a vendor deposits banknotes for their business account (or a person deposits their own), each note is checked, this time being associated with either the business or the individual.
To get a more accurate timeline you can deploy this type of 'fake banknote checker' to businesses everywhere, under the guise of trying to cut down fraud (technically true, but not the only reason). Making them 4G/5G connected provides an upload route for the details of each note (and prevents the WiFI snooping that would otherwise take place). As the deployment progresses so does the information captured, allowing an organisation to trace the path of a banknote, but more importantly where an individual has been based on the path a banknote has taken. It's not a perfect science, but it helps track individuals that don't want to be tracked.
With digital currency and the tracking that takes place, cash has become the go-to for small/medium acts of fraud. It would be of no surprise if agencies wanted to better track the movements of cash in order to catch those in the act. Is this currently being done is a question the public don't have the answer to, but is something that is technically feasible and that would help cut down on fraud (as even notes without fingerprints tell a tale of their own).